This is an index of articles relating to electronics

Electronics

Electronics is the branch of science, engineering and technology that deals with electrical circuits involving active electrical components such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive interconnection technologies...

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16VSB

16VSB

16VSB is an abbreviation for 16-level vestigial sideband modulation, capable of transmitting four bits at a time.-How it works:Other slower but more rugged forms of VSB include 2VSB, 4VSB, and 8VSB...

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2VSB

2VSB

In telecommunications, 2VSB is an abbreviation for 2-level vestigial sideband modulation, a transmission method capable of transmitting one bit at a time.Other faster but less rugged forms include 4VSB, 8VSB, and 16VSB....

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32VSB

32VSB

32VSB is an acronym for 32-level vestigial sideband modulation, capable of transmitting five bits at a time.32VSB is rarely used, because receivers have more trouble distinguishing between so many fine levels of modulation...

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4000 series

4000 series

The 4000 series is a family of industry standard integrated circuits which implement a variety of logic functions using Complementary Metal–Oxide–Semiconductor technology, and are still in use today. They were introduced by RCA as CD4000 COS/MOS series in 1968, as a lower power and more versatile...

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4VSB

4VSB

4VSB is an abbreviation for 4-level vestigial sideband modulation, capable of transmitting two bits at a time. Other faster but less rugged forms include 8VSB and 16VSB. While 2VSB is more rugged, it is also slower....

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555 timer IC

555 timer IC

The 555 timer IC is an integrated circuit used in a variety of timer, pulse generation and oscillator applications. The part is still in widespread use, thanks to its ease of use, low price and good stability. , it was estimated that 1 billion units are manufactured every year.- Design :The IC...

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7400 series

7400 series

The 7400 series of transistor-transistor logic integrated circuits are historically important as the first widespread family of TTL integrated circuit logic. It was used to build the mini and mainframe computers of the 1960s and 1970s...

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8VSB

8VSB

8VSB is the modulation method used for broadcast in the ATSC digital television standard. ATSC and 8VSB modulation is used primarily in North America; in contrast, the DVB-T standard uses COFDM....

A

Absolute gain (physics) –
Acceptance pattern –
Access control

Access control

Access control refers to exerting control over who can interact with a resource. Often but not always, this involves an authority, who does the controlling. The resource can be a given building, group of buildings, or computer-based information system...

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Access time

Access time

Access time is the time delay or latency between a request to an electronic system, and the access being completed or the requested data returned....

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Acoustic coupler

Acoustic coupler

In telecommunications, the term acoustic coupler has the following meanings:# An interface device for coupling electrical signals by acoustical means—usually into and out of a telephone instrument....

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Adaptive communications

Adaptive communications

Adaptive communications can mean any communications system, or portion thereof, that automatically uses feedback information obtained from the system itself or from the signals carried by the system to modify dynamically one or more of the system operational parameters to improve system performance...

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Adder

Adder (electronics)

In electronics, an adder or summer is a digital circuit that performs addition of numbers.In many computers and other kinds of processors, adders are used not only in the arithmetic logic unit, but also in other parts of the processor, where they are used to calculate addresses, table indices, and...

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Adjacent-channel interference

Adjacent-channel interference

Adjacent-channel interference is interference caused by extraneous power from a signal in an adjacent channel. ACI may be caused by inadequate filtering , improper tuning or poor frequency control .ACI is distinguished from crosstalk.Broadcast...

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Alarm sensor

Alarm sensor

In telecommunication, the term alarm sensor has the following meanings:1. In communications systems, a device that can sense an abnormal condition within the system and provide a signal indicating the presence or nature of the abnormality to either a local or remote alarm indicator, and may...

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Aliasing

Aliasing

In signal processing and related disciplines, aliasing refers to an effect that causes different signals to become indistinguishable when sampled...

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Allied Radio

Allied Radio

Allied Radio was an American radio manufacturer and retailer, which sold radio sets, tubes, capacitors , amateur radio equipment, citizen's band radios, miscellaneous communications equipment, electronic kits, and consumer audio systems through retail stores and mail-order.-History:Beginning in...

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Alternate party

Alternate party

Alternate party diversion is an optional feature of telephone services, whereby a call may be routed to a different number based on time-out and precedence schemes set up by the customer.-Technical definition:...

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Alternating current

Alternating current

In alternating current the movement of electric charge periodically reverses direction. In direct current , the flow of electric charge is only in one direction....

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AM radio –
Amateur radio

Amateur radio

Amateur radio is the use of designated radio frequency spectrum for purposes of private recreation, non-commercial exchange of messages, wireless experimentation, self-training, and emergency communication...

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Ambient noise level

Ambient noise level

In atmospheric sounding and noise pollution, ambient noise level is the background sound pressure level at a given location, normally specified as a reference level to study a new intrusive sound source.Ambient sound levels are often measured in order to map sound conditions over a...

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American Radio Relay League

American Radio Relay League

The American Radio Relay League is the largest membership association of amateur radio enthusiasts in the USA. ARRL is a non-profit organization, and was founded in May 1914 by Hiram Percy Maxim of Hartford, Connecticut...

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Ammeter

Ammeter

An ammeter is a measuring instrument used to measure the electric current in a circuit. Electric currents are measured in amperes , hence the name. Instruments used to measure smaller currents, in the milliampere or microampere range, are designated as milliammeters or microammeters...

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Ampere

Ampere

The ampere , often shortened to amp, is the SI unit of electric current and is one of the seven SI base units. It is named after André-Marie Ampère , French mathematician and physicist, considered the father of electrodynamics...

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Amplifier

Amplifier

Generally, an amplifier or simply amp, is a device for increasing the power of a signal.In popular use, the term usually describes an electronic amplifier, in which the input "signal" is usually a voltage or a current. In audio applications, amplifiers drive the loudspeakers used in PA systems to...

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Amplitude distortion

Amplitude distortion

Amplitude distortion is distortion occurring in a system, subsystem, or device when the output amplitude is not a linear function of the input amplitude under specified conditions....

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Amplitude modulation

Amplitude modulation

Amplitude modulation is a technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. AM works by varying the strength of the transmitted signal in relation to the information being sent...

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Analog computer

Analog computer

An analog computer is a form of computer that uses the continuously-changeable aspects of physical phenomena such as electrical, mechanical, or hydraulic quantities to model the problem being solved...

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Analog decoding –
Analog

Analog signal

An analog or analogue signal is any continuous signal for which the time varying feature of the signal is a representation of some other time varying quantity, i.e., analogous to another time varying signal. It differs from a digital signal in terms of small fluctuations in the signal which are...

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Analog to digital converter –
Analogue switch

Analogue switch

The analog switch, also called the bilateral switch, is an electronic component that behaves in a similar way to a relay, but has no moving parts. The switching element is normally a MOSFET transistor...

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Analysis of resistive circuits

Analysis of resistive circuits

A network, in the context of electronics, is a collection of interconnected components. Network analysis is the process of finding the voltages across, and the currents through, every component in the network. There are a number of different techniques for achieving this...

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Angular misalignment loss

Angular misalignment loss

In waveguide design and construction, angular misalignment loss is power loss caused by the deviation from optimum angular alignment of the axes of source-to-waveguide, waveguide-to-waveguide, or waveguide-to-detector. The waveguide may be dielectric or metallic...

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Antenna –
Antenna blind cone

Antenna blind cone

In telecommunications, antenna blind cone is the volume of space, usually approximately conical with its vertex at the antenna, that cannot be scanned by an antenna because of limitations of the antenna radiation pattern and mount.Note: An example of an antenna blind cone is that of an Air Route...

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Antenna effective area

Antenna effective area

In telecommunications, antenna effective area or effective aperture expresses an antenna's ability to collect an incident radio wave and deliver it as an electrical current at the antenna's terminals...

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Antenna gain

Antenna gain

In electromagnetics, an antenna's power gain or simply gain is a key performance figure which combines the antenna's directivity and electrical efficiency. As a transmitting antenna, the figure describes how well the antenna converts input power into radio waves headed in a specified direction...

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Antenna height above average terrain

Antenna height above average terrain

In United States telecommunication terminology, antenna height above average terrain is the antenna height above the average terrain elevations from 3.2 to 16 kilometers from the antenna for the eight directions spaced evenly for each 45° of azimuth starting with true north.In general, a different...

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Antenna noise temperature

Antenna noise temperature

In telecommunication, antenna noise temperature is the temperature of a hypothetical resistor at the input of an ideal noise-free receiver that would generate the same output noise power per unit bandwidth as that at the antenna output at a specified frequency....

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Antenna theory –
Aperiodic antenna –
Aperture (antenna) –
Aperture illumination –
Aperture-to-medium coupling loss

Aperture-to-medium coupling loss

In telecommunication, aperture-to-medium coupling loss is the difference between the theoretical gain of a very large antenna, such as the antennas in beyond-the-horizon microwave links, and the gain that can be realized in practice....

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Apollo Guidance Computer

Apollo Guidance Computer

The Apollo Guidance Computer provided onboard computation and control for guidance, navigation, and control of the Command Module and Lunar Module spacecraft of the Apollo program...

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Arithmetic and logical unit –
Armstrong oscillator –
ARRL –
Articulation score

Articulation score

In telecommunication, an articulation score is a subjective measure of the intelligibility of a voice system in terms of the percentage of words correctly understood over a channel perturbed by interference....

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Astable –
Asymmetric Digital Subscriber Line

Asymmetric Digital Subscriber Line

Asymmetric digital subscriber line is a type of digital subscriber line technology, a data communications technology that enables faster data transmission over copper telephone lines than a conventional voiceband modem can provide. It does this by utilizing frequencies that are not used by a voice...

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Asynchronous communications system –
Asynchronous operation

Asynchronous operation

In telecommunications, asynchronous operation or asynchronous working is where a sequence of operations is executed such that the operations are executed out of time coincidence with any event...

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Asynchronous start-stop

Asynchronous start-stop

Asynchronous serial communication describes an asynchronous, serial transmission protocol in which a start signal is sent prior to each byte, character or code word and a stop signal is sent after each code word...

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Atmospheric duct

Atmospheric duct

In telecommunication, an atmospheric duct is a horizontal layer in the lower atmosphere in which the vertical refractive index gradients are such that radio signals are guided or ducted, tend to follow the curvature of the Earth, and experience less attenuation in the ducts than they would if...

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Atmospheric waveguide

Atmospheric waveguide

An atmospheric waveguide is an atmospheric flow feature that improves the propagation of certain atmospheric waves.The effect arises because wave parameters such as group velocity or vertical wavenumber depend on mean flow direction and strength...

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Attenuation

Attenuation

In physics, attenuation is the gradual loss in intensity of any kind of flux through a medium. For instance, sunlight is attenuated by dark glasses, X-rays are attenuated by lead, and light and sound are attenuated by water.In electrical engineering and telecommunications, attenuation affects the...

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Audible ringing tone –
Audio system measurements

Audio system measurements

Audio system measurements are made for several purposes. Designers take measurements so that they can specify the performance of a piece of equipment. Maintenance engineers make them to ensure equipment is still working to specification, or to ensure that the cumulative defects of an audio path are...

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Audiophile

Audiophile

An audiophile is a person who enjoys listening to recorded music, usually in a home. Some audiophiles are more interested in collecting and listening to music, while others are more interested in collecting and listening to audio components, whose "sound quality" they consider as important as the...

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Automatic call distributor

Automatic call distributor

In telephony, an Automatic Call Distributor , also known as Automated Call Distribution, is a device or system that distributes incoming calls to a specific group of terminals that agents use. It is often part of a computer telephony integration system.Routing incoming calls is the task of the ACD...

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Automatic data processing

Automatic data processing

In telecommunication, the term automatic data processing has the following meanings:#An interacting assembly of procedures, processes, methods, personnel, and equipment to perform automatically a series of data processing operations on data...

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Automatic gain control

Automatic gain control

Automatic gain control is an adaptive system found in many electronic devices. The average output signal level is fed back to adjust the gain to an appropriate level for a range of input signal levels...

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Automatic link establishment

Automatic link establishment

Automatic Link Establishment, commonly known as ALE, is the worldwide de facto standard for digitally initiating and sustaining HF radio communications. ALE is a feature in an HF communications radio transceiver system, that enables the radio station to make contact, or initiate a circuit, between...

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Automatic number identification

Automatic number identification

Automatic number identification is a feature of telephony intelligent network services that permits subscribers to display or capture the billing telephone number of a calling party. In the United States it is part of Inward Wide Area Telephone Service . ANI service was created by AT&T for...

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Automatic sounding

Automatic sounding

In telecommunication, automatic sounding is the testing of selected channels for quality by providing a very brief identifying transmission that may be used by other stations to evaluate connectivity, and availability, and to identify known working channels for immediate or later use for...

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Automatic switching system

Automatic switching system

In data communications, an automatic switching system is a switching system in which all the operations required to execute the three phases of Information transfer transactions are automatically executed in response to signals from a user end-instrument....

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Autovon

Autovon

AUTOVON, short for Automatic Voice Network, was an American military phone system built in 1963 to survive nuclear attacks. AUTOVON was first established in the United States, using the Army's SCAN system. Around the mid-1970s AUTOVON expanded to the United Kingdom, Asia, the Middle East, and Panama...

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Availability

Availability

In telecommunications and reliability theory, the term availability has the following meanings:* The degree to which a system, subsystem, or equipment is in a specified operable and committable state at the start of a mission, when the mission is called for at an unknown, i.e., a random, time...

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Available line

Available line

In voice, video, or data communications, the term available line is a circuit between two points that is ready for service, but is in the idle state. Antonyms include busy line, unavailable, engaged, and out of service.In facsimile transmission, it is the portion of the scan line that can be...

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Avalanche diode

Avalanche diode

In electronics, an avalanche diode is a diode that is designed to go through avalanche breakdown at a specified reverse bias voltage. The junction of an avalanche diode is designed to prevent current concentration at hot spots, so that the diode is undamaged by the breakdown...

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Azimuth

B

Backplane

Backplane

A backplane is a group of connectors connected in parallel with each other, so that each pin of each connector is linked to the same relative pin of all the other connectors forming a computer bus. It is used as a backbone to connect several printed circuit boards together to make up a complete...

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Backscattering –
Back-to-back connection

Back-to-back connection

-Telecommunications:In telecommunications, a back-to-back connection is a direct connection between either:# the output of a transmitting device and the input of an associated receiving device...

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Backward channel

Backward channel

In a data circuit a backward channel is the channel that passes data in a direction opposite to that of its associated forward channel. The backward channel is usually used for transmission of request, supervisory, acknowledgement, or error-control signals. The direction of flow of these signals...

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Balance return loss

Balance return loss

In telecommunications, balance return loss is one of two things:* A measure of the degree of balance between two impedances connected to two conjugate sides of a hybrid set, coil, network, or junction....

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Balanced line

Balanced line

In telecommunications and professional audio, a balanced line or balanced signal pair is a transmission line consisting of two conductors of the same type, each of which have equal impedances along their lengths and equal impedances to ground and to other circuits. The chief advantage of the...

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Balancing network

Balancing network

In a hybrid set, hybrid coil, or resistance hybrid, balancing network is a circuit used to match, i.e., to balance, the impedance of a uniform transmission line, over a selected range of frequencies...

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Ball grid array

Ball grid array

A ball grid array is a type of surface-mount packaging used for integrated circuits.- Description :The BGA is descended from the pin grid array , which is a package with one face covered with pins in a grid pattern. These pins conduct electrical signals from the integrated circuit to the printed...

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Band gap

Band gap

In solid state physics, a band gap, also called an energy gap or bandgap, is an energy range in a solid where no electron states can exist. In graphs of the electronic band structure of solids, the band gap generally refers to the energy difference between the top of the valence band and the...

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Band-stop filter

Band-stop filter

In signal processing, a band-stop filter or band-rejection filter is a filter that passes most frequencies unaltered, but attenuates those in a specific range to very low levels. It is the opposite of a band-pass filter...

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Bandwidth compression

Bandwidth compression

In telecommunication, the term bandwidth compression has the following meanings:*The reduction of the bandwidth needed to transmit a given amount of data in a given time.*The reduction of the time needed to transmit a given amount of data in a given bandwidth....

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Bare particular –
Barrage jamming

Barrage jamming

Barrage jamming: jamming accomplished by transmitting a band of frequencies that is large with respect to the bandwidth of a single emitter. Barrage jamming may be accomplished by presetting multiple jammers on adjacent frequencies, by using a single wideband transmitter, or by using a transmitter...

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Baseband

Baseband

In telecommunications and signal processing, baseband is an adjective that describes signals and systems whose range of frequencies is measured from close to 0 hertz to a cut-off frequency, a maximum bandwidth or highest signal frequency; it is sometimes used as a noun for a band of frequencies...

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Battery (electricity)

Battery (electricity)

An electrical battery is one or more electrochemical cells that convert stored chemical energy into electrical energy. Since the invention of the first battery in 1800 by Alessandro Volta and especially since the technically improved Daniell cell in 1836, batteries have become a common power...

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Baud

Baud

In telecommunications and electronics, baud is synonymous to symbols per second or pulses per second. It is the unit of symbol rate, also known as baud rate or modulation rate; the number of distinct symbol changes made to the transmission medium per second in a digitally modulated signal or a...

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Baudot code

Baudot code

The Baudot code, invented by Émile Baudot, is a character set predating EBCDIC and ASCII. It was the predecessor to the International Telegraph Alphabet No 2 , the teleprinter code in use until the advent of ASCII. Each character in the alphabet is represented by a series of bits, sent over a...

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BCS theory

BCS theory

BCS theory — proposed by Bardeen, Cooper, and Schrieffer in 1957 — is the first microscopic theory of superconductivity since its discovery in 1911. The theory describes superconductivity as a microscopic effect caused by a "condensation" of pairs of electrons into a boson-like state...

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Beam diameter

Beam diameter

The beam diameter or beam width of an electromagnetic beam is the diameter along any specified line that is perpendicular to the beam axis and intersects it. Since beams typically do not have sharp edges, the diameter can be defined in many different ways. Five definitions of the beam width are in...

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Beam divergence

Beam divergence

The beam divergence of an electromagnetic beam is an angular measure of the increase in beam diameter or radius with distance from the optical aperture or antenna aperture from which the electromagnetic beam emerges. The term is relevant only in the "far field", away from any focus of the beam...

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Beam steering

Beam steering

Beam steering is about changing the direction of the main lobe of a radiation pattern.In radio systems, beam steering may be accomplished by switching antenna elements or by changing the relative phases of the RF signals driving the elements.In optical systems, beam steering may be accomplished by...

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Beamwidth

Beamwidth

In telecommunication, the term beamwidth has the following meanings:1. In the radio regime, of an antenna pattern, the angle between the half-power points of the main lobe, when referenced to the peak effective radiated power of the main lobe....

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Bel

Decibel

The decibel is a logarithmic unit that indicates the ratio of a physical quantity relative to a specified or implied reference level. A ratio in decibels is ten times the logarithm to base 10 of the ratio of two power quantities...

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Biconical antenna

Biconical antenna

In radio systems, a biconical antenna is a broad-bandwith antenna made of two roughly conical conductive objects, nearly touching at their points. Biconical antennas are broadband dipole antennas, typically exhibiting a bandwidth of 3 octaves or more....

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Big ugly dish –
Bilateral synchronization

Bilateral synchronization

In telecommunication, bilateral synchronization is a synchronization control system between exchanges A and B in which the clock at telephone exchange A controls the data received at exchange B and the clock at exchange B controls the data received at exchange A.Bilateral synchronization is...

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Billboard antenna –
Binary classification

Binary classification

Binary classification is the task of classifying the members of a given set of objects into two groups on the basis of whether they have some property or not. Some typical binary classification tasks are...

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Binaural recording

Binaural recording

Binaural recording is a method of recording sound that uses two microphones, arranged with the intent to create a 3-D stereo sound sensation for the listener of actually being in the room with the performers or instruments. This effect is often created using a technique known as "Dummy head...

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Bipolar junction transistor

Bipolar junction transistor

|- align = "center"| || PNP|- align = "center"| || NPNA bipolar transistor is a three-terminal electronic device constructed of doped semiconductor material and may be used in amplifying or switching applications. Bipolar transistors are so named because their operation involves both electrons...

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Bipolar signal

Bipolar signal

In telecommunication, a bipolar signal is a signal that may assume either of two polarities, neither of which is zero.A bipolar signal may have a two-state non-return-to-zero or a three-state return-to-zero binary coding scheme....

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Bit inversion

Bit inversion

In telecommunications, bit inversion means the changing of the state of a bit to the opposite state, i.e. the changing of a 0 bit to 1 or of a 1 bit to 0. It also refers to the changing of a state representing a given bit to the opposite state....

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Bit pairing

Bit pairing

In telecommunication, bit pairing is the practice of establishing, within a code set, a number of subsets that have an identical bit representation except for the state of a specified bit....

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Bit robbing –
Bit stuffing

Bit stuffing

In data transmission and telecommunication, bit stuffing is the insertion of noninformation bits into data...

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Bit synchronous operation

Bit synchronous operation

Bit synchronous operation is a type of digital communication in which the data circuit terminating equipment , data terminal equipment , and transmitting circuits are all operated in bit synchronism with a clock signal....

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Bit-count integrity

Bit-count integrity

In telecommunication, the term bit-count integrity has the following meanings:#In message communications, the preservation of the exact number of bits that are in the original message....

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Bits per second –
Black facsimile transmission

Black facsimile transmission

In telecommunication, the term black facsimile transmission has the following meanings:# In facsimile systems using amplitude modulation, that form of transmission in which the maximum transmitted power corresponds to the maximum density of the subject....

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Black recording

Black recording

In telecommunication, the term black recording has the following meanings:1. In facsimile systems using amplitude modulation, recording in which the maximum received power corresponds to the maximum density of the record medium....

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Blanketing

Blanketing

Blanketing is interference caused by strong radio signals. Although the spectral mask of a radio station's transmitter suppresses spurious emissions on other frequencies in the band, being extremely close to a station may allow them to still be strong enough to cause significant interference...

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Bluetooth

Bluetooth

Bluetooth is a proprietary open wireless technology standard for exchanging data over short distances from fixed and mobile devices, creating personal area networks with high levels of security...

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Blu-ray Disc

Blu-ray Disc

Blu-ray Disc is an optical disc storage medium designed to supersede the DVD format. The plastic disc is 120 mm in diameter and 1.2 mm thick, the same size as DVDs and CDs. Blu-ray Discs contain 25 GB per layer, with dual layer discs being the norm for feature-length video discs...

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BNC connector

BNC connector

The BNC connector ' is a common type of RF connector used for coaxial cable. It is used with radio, television, and other radio-frequency electronic equipment, test instruments, video signals, and was once a popular computer network connector. BNC connectors are made to match the characteristic...

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Boresight

Antenna boresight

In telecommunications and radar engineering, antenna boresight is the axis of maximum gain ) of a directional antenna. For most antennas the boresight is the axis of symmetry of the antenna...

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Breadboard

Breadboard

A breadboard is a construction base for prototyping of electronics. The term is commonly used to refer to solderless breadboard ....

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Bremsstrahlung

Bremsstrahlung

Bremsstrahlung is electromagnetic radiation produced by the deceleration of a charged particle when deflected by another charged particle, typically an electron by an atomic nucleus. The moving particle loses kinetic energy, which is converted into a photon because energy is conserved. The term is...

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Bridging loss

Bridging loss

Bridging loss is the loss, at a given frequency, that results when an impedance is connected across a transmission line. It is expressed as the ratio, in decibels, of the signal power delivered to a given point in a system downstream from the bridging point prior to bridging, to the signal power...

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Broadband Internet –
Broadband wireless access

Broadband wireless access

Wireless Broadband refers to technology that provides high-speed wireless Internet access or computer networking access over a wide area.-The term broadband:...

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Broadband

Broadband

The term broadband refers to a telecommunications signal or device of greater bandwidth, in some sense, than another standard or usual signal or device . Different criteria for "broad" have been applied in different contexts and at different times...

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Broadcasting

Broadcasting

Broadcasting is the distribution of audio and video content to a dispersed audience via any audio visual medium. Receiving parties may include the general public or a relatively large subset of thereof...

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Burst transmission

Burst transmission

In telecommunication, the term burst transmission or data burst has the following meanings:# Any relatively high-bandwidth transmission over a short period of time...

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Busy hour

Busy hour

Busy hour: In a communications system, the sliding 60-minute period during which occurs the maximum total traffic load in a given 24-hour period....

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Busy signal –
Bypass

Bypass (telecommunications)

In telecommunications, the term bypass has these meanings:# The use of any telecommunications facilities or services that circumvents those of the local exchange common carrier....

C

Cable modem

Cable modem

A cable modem is a type of network bridge and modem that provides bi-directional data communication via radio frequency channels on a HFC and RFoG infrastructure. Cable modems are primarily used to deliver broadband Internet access in the form of cable Internet, taking advantage of the high...

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Cable television

Cable television

Cable television is a system of providing television programs to consumers via radio frequency signals transmitted to televisions through coaxial cables or digital light pulses through fixed optical fibers located on the subscriber's property, much like the over-the-air method used in traditional...

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Caesium standard

Caesium standard

A caesium standard or caesium atomic clock is a primary frequency standard in which electronic transitions between the two hyperfine ground states of caesium-133 atoms are used to control the output frequency. They are one of the most accurate types of atomic clock...

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Call collision

Call collision

In telecommunications, a call collision is one of two things:#The contention that occurs when a terminal and data circuit-terminating equipment specify the same channel at the same time to transfer a call request and handle an incoming call...

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Call set-up time

Call set-up time

In telecommunication, the term call set-up time has the following meanings:#The overall length of time required to establish a circuit-switched call between users....

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Call-second

Call-second

In telecommunication, a call-second is a unit used to measure communications traffic density.Note 1: A call-second is equivalent to 1 call with a duration of 1 second....

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Capacitive coupling

Capacitive coupling

In electronics, capacitive coupling is the transfer of energy within an electrical network by means of the capacitance between circuit nodes. This coupling can have an intentional or accidental effect...

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Capacitor

Capacitor

A capacitor is a passive two-terminal electrical component used to store energy in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors separated by a dielectric ; for example, one common construction consists of metal foils separated...

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Capture effect

Capture effect

In telecommunication, the capture effect, or FM capture effect, is a phenomenon associated with FM reception in which only the stronger of two signals at, or near, the same frequency will be demodulated....

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Carbon nanotube

Carbon nanotube

Carbon nanotubes are allotropes of carbon with a cylindrical nanostructure. Nanotubes have been constructed with length-to-diameter ratio of up to 132,000,000:1, significantly larger than for any other material...

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Card standards

Card standards

Card standard may refer to any of a number of standards related to smartcards.* ISO/IEC 7810 Identification cards — Physical characteristics* ISO/IEC 7812 Identification cards — Identification of issuers...

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Carrier sense multiple access with collision detection

Carrier sense multiple access with collision detection

Carrier sense multiple access with collision detection is a Media Access Control method in which:*a carrier sensing scheme is used....

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Carrier shift

Carrier shift

In telecommunication, the term carrier shift has the following meanings:#In the transmission of binary or teletypewriter signals, keying in which the carrier frequency is shifted in one direction for marking signals and in the opposite direction for spacing signals.#In amplitude modulation, a...

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Carrier system

Carrier system

In telecommunication, a carrier system is a multichannel telecommunications system in which a number of individual channels are multiplexed for transmission...

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Carrier wave

Carrier wave

In telecommunications, a carrier wave or carrier is a waveform that is modulated with an input signal for the purpose of conveying information. This carrier wave is usually a much higher frequency than the input signal...

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Carrier-to-receiver noise density

Carrier-to-receiver noise density

In satellite communications, carrier-to-receiver noise density is the ratio of the received carrier power to the receiver noise power density.The carrier-to-receiver noise density ratio is usually expressed in dBHz....

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Carson bandwidth rule

Carson bandwidth rule

In telecommunication, Carson's bandwidth rule defines the approximate bandwidth requirements of communications system components for a carrier signal that is frequency modulated by a continuous or broad spectrum of frequencies rather than a single frequency. Carson's rule does not apply well when...

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Cassegrain antenna

Cassegrain antenna

In telecommunications and radar, a Cassegrain antenna is a parabolic antenna in which the feed radiator is mounted at or behind the surface of the concave main parabolic reflector dish and is aimed at a smaller convex secondary reflector suspended in front of the primary reflector...

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Category 5 cable

Category 5 cable

Category 5 cable is a twisted pair cable for carrying signals. This type of cable is used in structured cabling for computer networks such as Ethernet. It is also used to carry other signals such as telephony and video. The cable is commonly connected using punch down blocks and modular connectors...

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Cathode ray tube

Cathode ray tube

The cathode ray tube is a vacuum tube containing an electron gun and a fluorescent screen used to view images. It has a means to accelerate and deflect the electron beam onto the fluorescent screen to create the images. The image may represent electrical waveforms , pictures , radar targets and...

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Central processing unit

Central processing unit

The central processing unit is the portion of a computer system that carries out the instructions of a computer program, to perform the basic arithmetical, logical, and input/output operations of the system. The CPU plays a role somewhat analogous to the brain in the computer. The term has been in...

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Chadless tape –
Channel

Channel (communications)

In telecommunications and computer networking, a communication channel, or channel, refers either to a physical transmission medium such as a wire, or to a logical connection over a multiplexed medium such as a radio channel...

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Channel noise level

Channel noise level

In telecommunications, the term channel noise level has the following meanings:#The ratio of the channel noise at any point in a transmission system to an arbitrary level chosen as a reference....

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Channel reliability –
Character-count integrity

Character-count integrity

Character-count integrity is a telecommunications term for the ability of a certain link to preserve the number of characters in a message . Character-count integrity is not the same as character integrity, which requires that the characters delivered be, in fact, exactly the same as they were...

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Characteristic impedance

Characteristic impedance

The characteristic impedance or surge impedance of a uniform transmission line, usually written Z_0, is the ratio of the amplitudes of a single pair of voltage and current waves propagating along the line in the absence of reflections. The SI unit of characteristic impedance is the ohm...

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Charge-coupled device

Charge-coupled device

A charge-coupled device is a device for the movement of electrical charge, usually from within the device to an area where the charge can be manipulated, for example conversion into a digital value. This is achieved by "shifting" the signals between stages within the device one at a time...

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Chemical vapor deposition

Chemical vapor deposition

Chemical vapor deposition is a chemical process used to produce high-purity, high-performance solid materials. The process is often used in the semiconductor industry to produce thin films. In a typical CVD process, the wafer is exposed to one or more volatile precursors, which react and/or...

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Chirping

Chirping

In telecommunication, the term chirping has the following meanings:1. The rapid changing, as opposed to long-term drifting, of the frequency of an electromagnetic wave.Chirping is most often observed in pulsed operation of a source....

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Chroma subsampling

Chroma subsampling

Chroma subsampling is the practice of encoding images by implementing less resolution for chroma information than for luma information, taking advantage of the human visual system's lower acuity for color differences than for luminance....

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Circuit breaker

Circuit breaker

A circuit breaker is an automatically operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit. Its basic function is to detect a fault condition and, by interrupting continuity, to immediately discontinue electrical flow...

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Circuit noise level

Circuit noise level

Circuit noise level: At any point in a transmission system, the ratio of the circuit noise at that point to an arbitrary level chosen as a reference....

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Circuit reliability

Circuit reliability

Circuit reliability is the percentage of time an electronic circuit was available for use in a specified period of scheduled availability. Circuit reliability is given by where T o is the circuit total outage time, Ts is the circuit total scheduled time, and T a is the circuit total available time...

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Circuit restoration

Circuit restoration

In telecommunication, circuit restoration is the process by which a communications circuit is established between two users after disruption or loss of the original circuit...

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Circuit switching

Circuit switching

Circuit switching is a methodology of implementing a telecommunications network in which two network nodes establish a dedicated communications channel through the network before the nodes may communicate. The circuit guarantees the full bandwidth of the channel and remains connected for the...

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Circular polarization

Circular polarization

In electrodynamics, circular polarization of an electromagnetic wave is a polarization in which the electric field of the passing wave does not change strength but only changes direction in a rotary type manner....

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Circulator

Circulator

A circulator is a passive non-reciprocal three- or four-port device, in which microwave or radio frequency power entering any port is transmitted to the next port in rotation...

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Citizens' band radio

Citizens' band radio

Citizens' Band radio is, in many countries, a system of short-distance radio communications between individuals on a selection of 40 channels within the 27-MHz band. Citizens' Band is distinct from the FRS, GMRS, MURS and amateur radio...

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Cladding

Cladding (fiber optics)

Cladding is one or more layers of material of lower refractive index, in intimate contact with a core material of higher refractive index. The cladding causes light to be confined to the core of the fiber by total internal reflection at the boundary between the two. Light propagation in the...

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Clapp oscillator

Clapp oscillator

The Clapp oscillator is one of several types of electronic oscillator constructed from a transistor and a positive feedback network, using the combination of an inductance with a capacitor for frequency determination, thus also called LC oscillator.It was published by James Kilton Clapp in 1948...

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Clean room –
Clear channel –
Clearing

Clearing (telecommunications)

Clearing, in telecommunications means:* A sequence of events used to disconnect a call and return to the ready state. It is sometimes, particularly in the context of common channel signaling, called teardown....

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Clipping

Clipping (signal processing)

Clipping is a form of distortion that limits a signal once it exceeds a threshold. Clipping may occur when a signal is recorded by a sensor that has constraints on the range of data it can measure, it can occur when a signal is digitized, or it can occur any other time an analog or digital signal...

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Clock gating

Clock gating

Clock gating is a power-saving technique used in many synchronous circuits-Description:Clock gating is a popular technique used in many synchronous circuits for reducing dynamic power dissipation. Clock gating saves power by adding more logic to a circuit to prune the clock tree...

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Clock signal

Clock signal

In electronics and especially synchronous digital circuits, a clock signal is a particular type of signal that oscillates between a high and a low state and is utilized like a metronome to coordinate actions of circuits...

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Closed waveguide –
Closed-circuit television

Closed-circuit television

Closed-circuit television is the use of video cameras to transmit a signal to a specific place, on a limited set of monitors....

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CMOS

CMOS

Complementary metal–oxide–semiconductor is a technology for constructing integrated circuits. CMOS technology is used in microprocessors, microcontrollers, static RAM, and other digital logic circuits...

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Coaxial cable

Coaxial cable

Coaxial cable, or coax, has an inner conductor surrounded by a flexible, tubular insulating layer, surrounded by a tubular conducting shield. The term coaxial comes from the inner conductor and the outer shield sharing the same geometric axis...

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Co-channel interference

Co-channel interference

Co-channel interference or CCI is crosstalk from two different radio transmitters using the same frequency. There can be several causes of co-channel radio interference; four examples are listed here....

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Code division multiple access

Code division multiple access

Code division multiple access is a channel access method used by various radio communication technologies. It should not be confused with the mobile phone standards called cdmaOne, CDMA2000 and WCDMA , which are often referred to as simply CDMA, and use CDMA as an underlying channel access...

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Code word

Code word

In communication, a code word is an element of a standardized code or protocol. Each code word is assembled in accordance with the specific rules of the code and assigned a unique meaning...

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Coherence length

Coherence length

In physics, coherence length is the propagation distance from a coherent source to a point where an electromagnetic wave maintains a specified degree of coherence. The significance is that interference will be strong within a coherence length of the source, but not beyond it...

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Coherence time

Coherence time

For an electromagnetic wave, the coherence time is the time over which a propagating wave may be considered coherent...

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Coherence

Coherence (physics)

In physics, coherence is a property of waves that enables stationary interference. More generally, coherence describes all properties of the correlation between physical quantities of a wave....

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Coherent differential phase-shift keying –
Coherer

Coherer

The coherer was a primitive form of radio signal detector used in the first radio receivers during the wireless telegraphy era at the beginning of the twentieth century. Invented around 1890 by French scientist Édouard Branly, it consisted of a tube or capsule containing two electrodes spaced a...

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Coil

Coil

A coil is a series of loops. A coiled coil is a structure in which the coil itself is in turn also looping.-Electromagnetic coils:An electromagnetic coil is formed when a conductor is wound around a core or form to create an inductor or electromagnet...

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Coilgun

Coilgun

A coilgun is a type of projectile accelerator that consists of one or more coils used as electromagnets in the configuration of a synchronous linear motor which accelerate a magnetic projectile to high velocity...

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Collinear antenna array

Collinear antenna array

In telecommunications, a collinear antenna array is an array of dipole antennas mounted in such a manner that the corresponding elements of each antenna are parallel and collinear, that is they are located along a common line or axis....

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Collinear antenna array

Collinear antenna array

In telecommunications, a collinear antenna array is an array of dipole antennas mounted in such a manner that the corresponding elements of each antenna are parallel and collinear, that is they are located along a common line or axis....

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Collins Radio –
Colpitts oscillator

Colpitts oscillator

A Colpitts oscillator, invented in 1920 by American engineer Edwin H. Colpitts, is one of a number of designs for electronic oscillator circuits using the combination of an inductance with a capacitor for frequency determination, thus also called LC oscillator...

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Combat-net radio

Combat-net radio

In telecommunication, a combat-net radio is a radio operating in a network that provides a half-duplex circuit and uses either a single radio frequency or a discrete set of radio frequencies when in a frequency hopping mode....

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Combinational logic

Combinational logic

In digital circuit theory, combinational logic is a type of digital logic which is implemented by boolean circuits, where the output is a pure function of the present input only. This is in contrast to sequential logic, in which the output depends not only on the present input but also on the...

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Combined distribution frame

Combined distribution frame

In telecommunication, a combined distribution frame is a distribution frame that combines the functions of main and intermediate distribution frames and contains both vertical and horizontal terminating blocks....

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Common base

Common base

In electronics, a common-base amplifier is one of three basic single-stage bipolar junction transistor amplifier topologies, typically used as a current buffer or voltage amplifier...

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Common battery

Common battery

In telecommunication, a Common battery is a single electrical power source used to energize more than one circuit, electronic component, equipment, or system....

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Common collector

Common collector

In electronics, a common-collector amplifier is one of three basic single-stage bipolar junction transistor amplifier topologies, typically used as a voltage buffer...

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Common control

Common control

In telecommunication, a common control is an automatic telephone exchange arrangement in which the control equipment necessary for the establishment of connections is shared by being associated with a given call only during the period required to accomplish the control function for the given call...

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Common emitter

Common emitter

In electronics, a common-emitter amplifier is one of three basic single-stage bipolar-junction-transistor amplifier topologies, typically used as a voltage amplifier...

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Commonality

Commonality

Aviation commonality describes the economic and logistic benefits of operating a standardized fleet of aircraft that share common parts, training requirements, or other characteristics. Commonality lowers the cost of operating a fleet of aircraft by reducing the quantity and variety of spare parts...

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Common-mode interference

Common-mode interference

In telecommunication, the term common-mode interference has the following meanings:#Interference that appears on both signal leads , or the terminals of a measuring circuit, and ground....

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Communications center

Communications center

In telecommunication, the term communications center has the following meanings:# An agency charged with the responsibility for handling and controlling communications traffic...

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Communications satellite

Communications satellite

A communications satellite is an artificial satellite stationed in space for the purpose of telecommunications...

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Communications security

Communications security

Communications security is the discipline of preventing unauthorized interceptors from accessing telecommunications in an intelligible form, while still delivering content to the intended recipients. In the United States Department of Defense culture, it is often referred to by the abbreviation...

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Communications system engineering –
Communications system

Communications system

In telecommunication, a communications system is a collection of individual communications networks, transmission systems, relay stations, tributary stations, and data terminal equipment usually capable of interconnection and interoperation to form an integrated whole...

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Communications-electronics

Communications-electronics

In telecommunication, communications-electronics is the specialized field concerned with the use of electronic devices and systems for the acquisition or acceptance, processing, storage, display, analysis, protection, disposition, and transfer of information.C-E includes the wide range of...

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Compact audio cassette –
Compatible sideband transmission

Compatible sideband transmission

Compatible sideband transmission: Independent sideband transmission in which the carrier is deliberately reinserted at a lower level after its normal suppression to permit reception by conventional AM receivers....

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Composite image filter

Composite image filter

A composite image filter is an electronic filter consisting of multiple image filter sections of two or more different types.The image method of filter design determines the properties of filter sections by calculating the properties they have in an infinite chain of such sections. In this, the...

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Composite video

Composite video

Composite video is the format of an analog television signal before it is combined with a sound signal and modulated onto an RF carrier. In contrast to component video it contains all required video information, including colors in a single line-level signal...

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Compulsator

Compulsator

A compensated pulsed alternator, also known by the portmanteau compulsator, is a form of power supply.As the name suggests, it is an alternator that is "compensated" to make it better at delivering pulses of electrical energy than a normal alternator.- Description and operation:The principle is...

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Computer

Computer

A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...

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Concentrator

Concentrator

In telecommunication, the term concentrator has the following meanings:# In data transmission, a functional unit that permits a common path to handle more data sources than there are channels currently available within the path...

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Conditioning equipment

Conditioning equipment

In telecommunication, the term conditioning equipment has the following meanings:# At junctions of circuits, equipment used to obtain desired circuit characteristics, such as matched transmission levels, matched impedances, and equalization between facilities.# Corrective networks used to improve...

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Conducted interference

Conducted interference

In telecommunications, the term conducted interference has the following meanings:*Interference resulting from noise or unwanted signals entering a device by conductive coupling, i.e., by direct coupling....

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Conduction band

Conduction band

In the solid-state physics field of semiconductors and insulators, the conduction band is the range of electron energies, higher than that of the valence band, sufficient to free an electron from binding with its individual atom and allow it to move freely within the atomic lattice of the material...

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Conductive coupling

Conductive coupling

Conductive coupling is the transfer of electrical energy by means of physical contact via a conductive medium, in contrast to inductive coupling and capacitive coupling...

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Connections per circuit hour

Connections per circuit hour

In telecommunication, the term connections per circuit hour has the following meanings:*A unit of teletraffic measurement expressed as the number of connections established at a switching point per hour....

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Conservation of radiance –
Constant k filter

Constant k filter

Constant k filters, also k-type filters, are a type of electronic filter designed using the image method. They are the original and simplest filters produced by this methodology and consist of a ladder network of identical sections of passive components...

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Content delivery

Content delivery

Content delivery describes the delivery of media content such as audio, video, computer software and video games over a delivery medium such as broadcasting or the Internet.Content delivery has two parts:...

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Contention

Contention (telecommunications)

In packet mode communication networks, contention is a media access method that is used to share a broadcast medium.-Collision detection and recovery:...

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Continuous Fourier transform

Continuous Fourier transform

The Fourier transform is a mathematical operation that decomposes a function into its constituent frequencies, known as a frequency spectrum. For instance, the transform of a musical chord made up of pure notes is a mathematical representation of the amplitudes of the individual notes that make...

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Continuous operation

Continuous operation

In telecommunication, the term continuous operation has the following meanings:#Operation in which certain components, such as nodes, facilities, circuits, or equipment, are in an operational state at all times....

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Continuous wave

Continuous wave

A continuous wave or continuous waveform is an electromagnetic wave of constant amplitude and frequency; and in mathematical analysis, of infinite duration. Continuous wave is also the name given to an early method of radio transmission, in which a carrier wave is switched on and off...

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Convolution

Convolution

In mathematics and, in particular, functional analysis, convolution is a mathematical operation on two functions f and g, producing a third function that is typically viewed as a modified version of one of the original functions. Convolution is similar to cross-correlation...

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Copper

Copper

Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...

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Cord circuit

Cord circuit

In telecommunication, a cord circuit is a switchboard circuit in which a plug-terminated cord is used to establish connections manually between user lines or between trunks and user lines. A number of cord circuits are furnished as part of the switchboard position equipment. The cords may be...

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Corner reflector

Corner reflector

A corner reflector is a retroreflector consisting of three mutually perpendicular, intersecting flat surfaces, which reflects waves back directly towards the source, but shifted . Unlike a simple mirror, they work for a relatively wide-angle field of view. The three intersecting surfaces often have...

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Cosmic noise

Cosmic noise

Cosmic noise and galactic radio noise is random noise that originates outside the Earth's atmosphere. It can be detected and heard on radio receivers.- Elaboration :Cosmic noise characteristics are similar to those of thermal noise...

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Costas loop

Costas loop

A Costas loop is a phase-locked loop used for carrier phase recovery from suppressed-carrier modulation signals, such as from double-sideband suppressed carrier signals. It was invented by John P. Costas at General Electric in the 1950s...

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Coulomb's law

Coulomb's law

Coulomb's law or Coulomb's inverse-square law, is a law of physics describing the electrostatic interaction between electrically charged particles. It was first published in 1785 by French physicist Charles Augustin de Coulomb and was essential to the development of the theory of electromagnetism...

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Counter

Counter

In digital logic and computing, a counter is a device which stores the number of times a particular event or process has occurred, often in relationship to a clock signal.- Electronic counters :...

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Coupling

Coupling (electronics)

In electronics and telecommunication, coupling is the desirable or undesirable transfer of energy from one medium, such as a metallic wire or an optical fiber, to another medium, including fortuitous transfer....

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Covert channel

Covert channel

In computer security, a covert channel is a type of computer security attack that creates a capability to transfer information objects between processes that are not supposed to be allowed to communicate by the computer security policy...

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Covert listening device

Covert listening device

A covert listening device, more commonly known as a bug or a wire, is usually a combination of a miniature radio transmitter with a microphone. The use of bugs, called bugging, is a common technique in surveillance, espionage and in police investigations.A bug does not have to be a device...

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CPU design

CPU design

CPU design is the design engineering task of creating a central processing unit , a component of computer hardware. It is a subfield of electronics engineering and computer engineering.- Overview :CPU design focuses on these areas:...

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CQD

CQD

CQD, transmitted in Morse code as  — · — ·    — — · —    — · ·  is one of the first distress signals adopted for radio use...

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C-QUAM

C-QUAM

C-QUAM is the method of AM stereo broadcasting used in Canada, the United States and most other countries. It was invented in 1977 by Norman Parker, Francis Hilbert, and Yoshio Sakaie, and published in an IEEE journal....

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Critical frequency

Critical frequency

In telecommunication, the term critical frequency has the following meanings:* In radio propagation by way of the ionosphere, the limiting frequency at or below which a wave component is reflected by, and above which it penetrates through, an ionospheric layer.* At vertical incidence, the limiting...

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Cross product

Cross product

In mathematics, the cross product, vector product, or Gibbs vector product is a binary operation on two vectors in three-dimensional space. It results in a vector which is perpendicular to both of the vectors being multiplied and normal to the plane containing them...

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Crossbar switch

Crossbar switch

In electronics, a crossbar switch is a switch connecting multiple inputs to multiple outputs in a matrix manner....

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Crosstalk –
Crystal filter

Crystal filter

A crystal filter is a special form of quartz crystal used in electronics systems, in particular communications devices. It provides a very precisely defined centre frequency and very steep bandpass characteristics, that is a very high Q factor—far higher than can be obtained with conventional...

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Crystal radio receiver

Crystal radio receiver

thumb|Boy listening to a modern crystal radioA crystal radio receiver, also called a crystal set or cat's whisker receiver, is a very simple radio receiver, popular in the early days of radio. It needs no battery or power source and runs on the power received from radio waves by a long wire antenna...

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Current –
Current bias –
Current-to-voltage converter

Current-to-voltage converter

In electronics, a transimpedance amplifier is an amplifier that converts current to voltage. Its input ideally has zero impedance, and the input signal is a current...

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Cutback technique

Cutback technique

In telecommunications, a cutback technique is a destructive technique for determining certain optical fiber transmission characteristics, such as attenuation and bandwidth.-Procedure:The measurement technique consists of:...

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Cutoff frequency

Cutoff frequency

In physics and electrical engineering, a cutoff frequency, corner frequency, or break frequency is a boundary in a system's frequency response at which energy flowing through the system begins to be reduced rather than passing through.Typically in electronic systems such as filters and...

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Cutoff wavelength

D

D region

D region

The D region is the portion of the ionosphere that exists approximately 50 to 95 km above the surface of the Earth.Note: Attenuation of radio waves, caused by ionospheric free-electron density generated by solar radiation, is pronounced during daylight hours. Because solar radiation is not...

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D-4

D4 video connector

A D-Terminal or D-tanshi is a type of analog video connector found on Japanese consumer electronics, typically HDTV, DVD, Blu-ray, D-VHS and HD DVD devices. It was developed by the EIAJ in its standard, RC-5237, for use in digital satellite broadcast tuners...

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Data bank

Data bank

In telecommunications, a data bank is a repository of information on one or more subjects that is organized in a way that facilitates local or remote information retrieval. A data bank may be either centralized or decentralized...

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Data circuit terminating equipment –
Data compaction

Data compaction

In telecommunication, data compaction is the reduction of the number of data elements, bandwidth, cost, and time for the generation, transmission, and storage of data without loss of information by eliminating unnecessary redundancy, removing irrelevancy, or using special coding.Examples of data...

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Data integrity

Data integrity

Data Integrity in its broadest meaning refers to the trustworthiness of system resources over their entire life cycle. In more analytic terms, it is "the representational faithfulness of information to the true state of the object that the information represents, where representational faithfulness...

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Data link

Data link

In telecommunication a data link is the means of connecting one location to another for the purpose of transmitting and receiving information. It can also refer to a set of electronics assemblies, consisting of a transmitter and a receiver and the interconnecting data telecommunication circuit...

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Data service unit

Data service unit

A data service unit, sometimes called a digital service unit, is a piece of telecommunications circuit terminating equipment that transforms digital data between telephone company lines and local equipment. The device converts bipolar digital signals coming ultimately from a digital circuit and...

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Data terminal equipment

Data terminal equipment

Data Terminal Equipment is an end instrument that converts user information into signals or reconverts received signals. These can also be called tail circuits. A DTE device communicates with the data circuit-terminating equipment...

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Data transmission circuit

Data transmission circuit

In telecommunication, data transmission circuit is the transmission media and the intervening equipment used for the transfer of data between data terminal equipments ....

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Data

Data

The term data refers to qualitative or quantitative attributes of a variable or set of variables. Data are typically the results of measurements and can be the basis of graphs, images, or observations of a set of variables. Data are often viewed as the lowest level of abstraction from which...

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Datasheet

Datasheet

thumb|A floppy disk controller datasheet.A datasheet, data sheet, or spec sheet is a document summarizing the performance and other technical characteristics of a product, machine, component , material, a subsystem or software in sufficient detail to be used by a design engineer to integrate the...

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dBa

A-weighting

A Weighting curve is a graph of a set of factors, that are used to 'weight' measured values of a variable according to their importance in relation to some outcome. The most commonly known example is frequency weighting in sound level measurement where a specific set of weighting curves known as A,...

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DBm

DBm

dBm is an abbreviation for the power ratio in decibels of the measured power referenced to one milliwatt . It is used in radio, microwave and fiber optic networks as a convenient measure of absolute power because of its capability to express both very large and very small values in a short form...

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DBrn

DBrn

The symbol dBrn or dB is an abbreviation for decibels above reference noise.Weighted noise power in dB is referred to 1.0 picowatt. Thus, 0 dBrn = -90 dBm...

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DDR SDRAM

DDR SDRAM

Double data rate synchronous dynamic random access memory is a class of memory integrated circuits used in computers. DDR SDRAM has been superseded by DDR2 SDRAM and DDR3 SDRAM, neither of which are either forward or backward compatible with DDR SDRAM, meaning that DDR2 or DDR3 memory modules...

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Degree of isochronous distortion

Degree of isochronous distortion

The degree of isochronous distortion, in data transmission, is the ratio of the absolute value of the maximum measured difference between the actual and the theoretical intervals separating any two significant instants of modulation , to the unit interval. These instants are not necessarily...

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Delay line –
Delta modulation

Delta modulation

Delta modulation is an analog-to-digital and digital-to-analog signal conversion technique used for transmission of voice information where quality is not of primary importance. DM is the simplest form of differential pulse-code modulation where the difference between successive samples is encoded...

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Demand assignment

Demand assignment

In telecommunication, a demand assignment is a method which several users share access to a communications channel on a real-time basis, i.e., a user needing to communicate with another user on the same network requests the required circuit, uses it, and when the call is finished, the circuit is...

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Demand factor

Demand factor

In telecommunication, electronics and the electrical power industry, the term demand factor has the following meanings:1. The ratio of the maximum real power consumed by a system to the maximum real power that would be consumed if the entire load connected to the system were to be activated at...

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Demand load

Demand load

In telecommunication, the term demand load can have the following meanings:* In general, the total power required by a facility. The demand load is the sum of the operational load and nonoperational demand loads...

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Demodulation

Demodulation

Demodulation is the act of extracting the original information-bearing signal from a modulated carrier wave.A demodulator is an electronic circuit that is used to recover the information content from the modulated carrier wave.These terms are traditionally used in connection with radio receivers,...

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Demodulator –
Departure angle –
Design objective

Design objective

Design objective : In communications systems, a desired performance characteristic for communications circuits and equipment that is based on engineering analyses, but is not considered feasible to mandate in a standard, or has not been tested....

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Despun antenna –
Deviation –
Dial-up –
Diamagnetism

Diamagnetism

Diamagnetism is the property of an object which causes it to create a magnetic field in opposition to an externally applied magnetic field, thus causing a repulsive effect. Specifically, an external magnetic field alters the orbital velocity of electrons around their nuclei, thus changing the...

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Dielectric constant

Dielectric constant

The relative permittivity of a material under given conditions reflects the extent to which it concentrates electrostatic lines of flux. In technical terms, it is the ratio of the amount of electrical energy stored in a material by an applied voltage, relative to that stored in a vacuum...

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Dielectric strength

Dielectric strength

In physics, the term dielectric strength has the following meanings:*Of an insulating material, the maximum electric field strength that it can withstand intrinsically without breaking down, i.e., without experiencing failure of its insulating properties....

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Dielectric waveguide –
Dielectric

Dielectric

A dielectric is an electrical insulator that can be polarized by an applied electric field. When a dielectric is placed in an electric field, electric charges do not flow through the material, as in a conductor, but only slightly shift from their average equilibrium positions causing dielectric...

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Differential amplifier

Differential amplifier

A differential amplifier is a type of electronic amplifier that amplifies the difference between two voltages but does not amplify the particular voltages.- Theory :Many electronic devices use differential amplifiers internally....

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Diffraction

Diffraction

Diffraction refers to various phenomena which occur when a wave encounters an obstacle. Italian scientist Francesco Maria Grimaldi coined the word "diffraction" and was the first to record accurate observations of the phenomenon in 1665...

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Digital access and cross-connect system –
Digital Audio Tape

Digital Audio Tape

Digital Audio Tape is a signal recording and playback medium developed by Sony and introduced in 1987. In appearance it is similar to a compact audio cassette, using 4 mm magnetic tape enclosed in a protective shell, but is roughly half the size at 73 mm × 54 mm × 10.5 mm. As...

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Digital circuit

Digital circuit

Digital electronics represent signals by discrete bands of analog levels, rather than by a continuous range. All levels within a band represent the same signal state...

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Digital filter

Digital filter

In electronics, computer science and mathematics, a digital filter is a system that performs mathematical operations on a sampled, discrete-time signal to reduce or enhance certain aspects of that signal. This is in contrast to the other major type of electronic filter, the analog filter, which is...

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Digital multiplex hierarchy

Digital multiplex hierarchy

In telecommunications, a digital multiplex hierarchy is a hierarchy consisting of an ordered repetition of tandem digital multiplexers that produce signals of successively higher data rates at each level of the hierarchy....

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Digital radio

Digital radio

Digital radio has several meanings:1. Today the most common meaning is digital radio broadcasting technologies, such as the digital audio broadcasting system, also known as Eureka 147. In these systems, the analog audio signal is digitized into zeros and ones, compressed using formats such as...

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Digital signal processing

Digital signal processing

Digital signal processing is concerned with the representation of discrete time signals by a sequence of numbers or symbols and the processing of these signals. Digital signal processing and analog signal processing are subfields of signal processing...

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Digital signal processor

Digital signal processor

A digital signal processor is a specialized microprocessor with an architecture optimized for the fast operational needs of digital signal processing.-Typical characteristics:...

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Digital to analog converter –
Digital transmission group

Digital transmission group

In telecommunication, a digital transmission group is a group of digitized voice or data channels or both with bit streams that are combined into a single digital bit stream for transmission over communications media....

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Digitizer –
DIN

Din

DIN or Din or din can have several meanings:* A din is a loud noise.* Dīn, an Arabic term meaning "religion" or "way of life".* Din is one of the ten aspects of the Ein Sof in Kabbalah ....

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Diode

Diode

In electronics, a diode is a type of two-terminal electronic component with a nonlinear current–voltage characteristic. A semiconductor diode, the most common type today, is a crystalline piece of semiconductor material connected to two electrical terminals...

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DIP switch

DIP switch

DIP switches are manual electric switches that are packaged in a group in a standard dual in-line package...

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Dipole antenna

Dipole antenna

A dipole antenna is a radio antenna that can be made of a simple wire, with a center-fed driven element. It consists of two metal conductors of rod or wire, oriented parallel and collinear with each other , with a small space between them. The radio frequency voltage is applied to the antenna at...

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Dipole

Dipole

In physics, there are several kinds of dipoles:*An electric dipole is a separation of positive and negative charges. The simplest example of this is a pair of electric charges of equal magnitude but opposite sign, separated by some distance. A permanent electric dipole is called an electret.*A...

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Direct bandgap –
Direct broadcast satellite

Direct broadcast satellite

Direct broadcast satellite is a term used to refer to satellite television broadcasts intended for home reception.A designation broader than DBS would be direct-to-home signals, or DTH. This has initially distinguished the transmissions directly intended for home viewers from cable television...

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Direct current

Direct current

Direct current is the unidirectional flow of electric charge. Direct current is produced by such sources as batteries, thermocouples, solar cells, and commutator-type electric machines of the dynamo type. Direct current may flow in a conductor such as a wire, but can also flow through...

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Direct distance dialing

Direct distance dialing

Direct distance dialing or direct dial is a telecommunications term for a network-provided service feature in which a call originator may, without operator assistance, call any other user outside the local calling area. DDD requires more digits in the number dialed than are required for calling...

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Direct ray –
Directional antenna

Directional antenna

A directional antenna or beam antenna is an antenna which radiates greater power in one or more directions allowing for increased performance on transmit and receive and reduced interference from unwanted sources....

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Directional coupler –
Directive gain –
Direct-sequence spread spectrum

Direct-sequence spread spectrum

In telecommunications, direct-sequence spread spectrum is a modulation technique. As with other spread spectrum technologies, the transmitted signal takes up more bandwidth than the information signal that is being modulated. The name 'spread spectrum' comes from the fact that the carrier signals...

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Discrete Fourier transform

Discrete Fourier transform

In mathematics, the discrete Fourier transform is a specific kind of discrete transform, used in Fourier analysis. It transforms one function into another, which is called the frequency domain representation, or simply the DFT, of the original function...

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Discrete

Discrete signal

A discrete signal or discrete-time signal is a time series consisting of a sequence of qualities...

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Dispersion-limited operation

Dispersion-limited operation

A dispersion-limited operation is an operation of a communications link in which signal waveform degradation attributable to the dispersive effects of the communications medium is the dominant mechanism that limits link performance. The dispersion is the filter-like effect that a link has on the...

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Distortion

Distortion

A distortion is the alteration of the original shape of an object, image, sound, waveform or other form of information or representation. Distortion is usually unwanted, and often many methods are employed to minimize it in practice...

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Distortion-limited operation

Distortion-limited operation

In telecommunication, distortion-limited operation is the condition prevailing when distortion of a received signal, rather than its attenuated amplitude , limits performance under stated operational conditions and limits....

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Distress radiobeacon –
Distributed switching

Distributed switching

Distributed switching is an architecture in which multiple processor-controlled switching units are distributed. There is often a hierarchy of switching elements, with a centralized host switch and with remote switches located close to concentrations of users....

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Diurnal phase shift

Diurnal phase shift

In telecommunication, diurnal phase shift is the phase shift of electromagnetic signals associated with daily changes in the ionosphere. The major changes usually occur during the period of time when sunrise or sunset is present at critical points along the path. Significant phase shifts may occur...

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Diversity reception –
DOD master clock –
Doping –
Double-sideband suppressed-carrier transmission

Double-sideband suppressed-carrier transmission

Double-sideband suppressed-carrier transmission : transmission in which frequencies produced by amplitude modulation are symmetrically spaced above and below the carrier frequency and the carrier level is reduced to the lowest practical level, ideally completely suppressed.In the double-sideband...

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Double-slit experiment

Double-slit experiment

The double-slit experiment, sometimes called Young's experiment, is a demonstration that matter and energy can display characteristics of both waves and particles...

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Drift

Drift (telecommunication)

In telecommunication, a drift is a comparatively long-term change in an attribute, value, or operational parameter of a system or equipment. The drift should be characterized, such as "diurnal frequency drift" and "output level drift." Drift is usually undesirable and unidirectional, but may be...

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Drop and insert

Drop and insert

In a multichannel transmission system, a drop and insert is a process that diverts a portion of the multiplexed aggregate signal at an intermediate point, and introduces a different signal for subsequent transmission in the same position, e.g., time slot or frequency band, previously occupied by...

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Dropout

Dropout (electronics)

Dropout within the realm of electronics and electrical engineering, has a number of uses.It is the dropping away of a flake of magnetic material from magnetic tape, leading to loss of signal, or a failure to properly read a binary character from data storage...

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Dual access

Dual access

In telecommunication, the term dual access has the following meanings:#The connection of a user to two switching centers by separate access lines using a single message routing indicator or telephone number....

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Dual impedance -
Dual in-line package

Dual in-line package

In microelectronics, a dual in-line package is an electronic device package with a rectangular housing and two parallel rows of electrical connecting pins. The package may be through-hole mounted to a printed circuit board or inserted in a socket.A DIP is usually referred to as a DIPn, where n is...

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Dual-modulus prescaler

Dual-modulus prescaler

A dual modulus prescaler is an electronic circuit used in high-frequency synthesizer designs to overcome the problem of generating narrowly-spaced frequencies that are nevertheless too high to be passed directly through the feedback loop of the system. The modulus of a prescaler is its frequency...

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Dual-tone multi-frequency

Dual-tone multi-frequency

Dual-tone multi-frequency signaling is used for telecommunication signaling over analog telephone lines in the voice-frequency band between telephone handsets and other communications devices and the switching center. The version of DTMF that is used in push-button telephones for tone dialing is...

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Duobinary signal –
Duplex

Duplex (telecommunications)

A duplex communication system is a system composed of two connected parties or devices that can communicate with one another in both directions. The term multiplexing is used when describing communication between more than two parties or devices....

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Duty cycle

Duty cycle

In engineering, the duty cycle of a machine or system is the time that it spends in an active state as a fraction of the total time under consideration....

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DXCC –
Dynamic range

Dynamic range

Dynamic range, abbreviated DR or DNR, is the ratio between the largest and smallest possible values of a changeable quantity, such as in sound and light. It is measured as a ratio, or as a base-10 or base-2 logarithmic value.-Dynamic range and human perception:The human senses of sight and...

E

Earphone –
Earpiece –
Earth's magnetic field

Earth's magnetic field

Earth's magnetic field is the magnetic field that extends from the Earth's inner core to where it meets the solar wind, a stream of energetic particles emanating from the Sun...

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EDIF

EDIF

EDIF is a vendor-neutral format in which to store Electronic netlists and schematics. It was one of the first attempts to establish a neutral data exchange format for the electronic design automation industry. The goal was to establish a common format from which the proprietary formats of the EDA...

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EEPROM

EEPROM

EEPROM stands for Electrically Erasable Programmable Read-Only Memory and is a type of non-volatile memory used in computers and other electronic devices to store small amounts of data that must be saved when power is removed, e.g., calibration...

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Effective antenna gain contour –
Effective boresight area –
Effective data transfer rate

Effective data transfer rate

In telecommunication, effective data transfer rate is the average number of units of data, such as bits, characters, blocks, or frames, transferred per unit time from a source and accepted as valid by a sink....

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Effective Earth radius

Effective Earth radius

In telecommunication, effective Earth radius is the radius of a hypothetical Earth for which the distance to the radio horizon, assuming rectilinear propagation, is the same as that for the actual Earth with an assumed uniform vertical gradient of atmospheric refractive index.Note: For the...

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Effective height

Effective height

In telecommunication, the term effective height can refer to the height of the center of radiation of an antenna above the effective ground level. Or in low-frequency applications involving loaded or nonloaded vertical antennas, the moment of the current distribution in the vertical section...

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Effective input noise temperature

Effective input noise temperature

In telecommunications, effective input noise temperature is the source noise temperature in a two-port network or amplifier that will result in the same output noise power, when connected to a noise-free network or amplifier, as that of the actual network or amplifier connected to a noise-free source...

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Effective isotropically radiated power –
Effective monopole radiated power –
Effective radiated power

Effective radiated power

In radio telecommunications, effective radiated power or equivalent radiated power is a standardized theoretical measurement of radio frequency energy using the SI unit watts, and is determined by subtracting system losses and adding system gains...

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Effective transmission rate

Effective transmission rate

In telecommunications, effective transmission rate is the rate at which information is processed by a transmission facility....

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Efficiency factor

Efficiency factor

-Data communication:In data communications, the ratio of the time to transmit a text automatically at a specified modulation rate to the time actually required to receive the same text at a specified maximum error rate....

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E-layer –
Electric charge

Electric charge

Electric charge is a physical property of matter that causes it to experience a force when near other electrically charged matter. Electric charge comes in two types, called positive and negative. Two positively charged substances, or objects, experience a mutual repulsive force, as do two...

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Electric current

Electric current

Electric current is a flow of electric charge through a medium.This charge is typically carried by moving electrons in a conductor such as wire...

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Electric field

Electric field

In physics, an electric field surrounds electrically charged particles and time-varying magnetic fields. The electric field depicts the force exerted on other electrically charged objects by the electrically charged particle the field is surrounding...

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Electric motor

Electric motor

An electric motor converts electrical energy into mechanical energy.Most electric motors operate through the interaction of magnetic fields and current-carrying conductors to generate force...

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Electric power transmission

Electric power transmission

Electric-power transmission is the bulk transfer of electrical energy, from generating power plants to Electrical substations located near demand centers...

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Electric power

Electric power

Electric power is the rate at which electric energy is transferred by an electric circuit. The SI unit of power is the watt.-Circuits:Electric power, like mechanical power, is represented by the letter P in electrical equations...

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Electrical conduction –
Electrical conductivity –
Electrical connector

Electrical connector

An electrical connector is an electro-mechanical device for joining electrical circuits as an interface using a mechanical assembly. The connection may be temporary, as for portable equipment, require a tool for assembly and removal, or serve as a permanent electrical joint between two wires or...

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Electrical current –
Electrical efficiency –
Element

Electrical element

Electrical elements are conceptual abstractions representing idealized electrical components, such as resistors, capacitors, and inductors, used in the analysis of electrical networks...

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Electrical engineering

Electrical engineering

Electrical engineering is a field of engineering that generally deals with the study and application of electricity, electronics and electromagnetism. The field first became an identifiable occupation in the late nineteenth century after commercialization of the electric telegraph and electrical...

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Electrical generator

Electrical generator

In electricity generation, an electric generator is a device that converts mechanical energy to electrical energy. A generator forces electric charge to flow through an external electrical circuit. It is analogous to a water pump, which causes water to flow...

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Impedance

Electrical impedance

Electrical impedance, or simply impedance, is the measure of the opposition that an electrical circuit presents to the passage of a current when a voltage is applied. In quantitative terms, it is the complex ratio of the voltage to the current in an alternating current circuit...

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Insulation

Electrical insulation

thumb|250px|[[Coaxial Cable]] with dielectric insulator supporting a central coreThis article refers to electrical insulation. For insulation of heat, see Thermal insulation...

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Electrical length

Electrical length

In telecommunications, electrical length is the length of a transmission medium or antenna element expressed as the number of wavelengths of the signal propagating in the medium....

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Load –
Electrical network

Electrical network

An electrical network is an interconnection of electrical elements such as resistors, inductors, capacitors, transmission lines, voltage sources, current sources and switches. An electrical circuit is a special type of network, one that has a closed loop giving a return path for the current...

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Circuit

Electrical network

An electrical network is an interconnection of electrical elements such as resistors, inductors, capacitors, transmission lines, voltage sources, current sources and switches. An electrical circuit is a special type of network, one that has a closed loop giving a return path for the current...

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Electrical resistance

Electrical resistance

The electrical resistance of an electrical element is the opposition to the passage of an electric current through that element; the inverse quantity is electrical conductance, the ease at which an electric current passes. Electrical resistance shares some conceptual parallels with the mechanical...

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Electrical room

Electrical room

An electrical room is a room or space in a building dedicated to electrical equipment. The size of the electrical room is usually proportional to the size of the building. In large buildings there may be a main and subsidiary electrical rooms...

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Electrical signal –
Electricity distribution

Electricity distribution

File:Electricity grid simple- North America.svg|thumb|380px|right|Simplified diagram of AC electricity distribution from generation stations to consumers...

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Electricity

Electricity

Electricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire...

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Electrochemical cell

Electrochemical cell

An electrochemical cell is a device capable of either deriving electrical energy from chemical reactions, or facilitating chemical reactions through the introduction of electrical energy. A common example of an electrochemical cell is a standard 1.5-volt "battery"...

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Electrochemistry

Electrochemistry

Electrochemistry is a branch of chemistry that studies chemical reactions which take place in a solution at the interface of an electron conductor and an ionic conductor , and which involve electron transfer between the electrode and the electrolyte or species in solution.If a chemical reaction is...

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Electrode

Electrode

An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit...

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Electrodynamics –
Electrolytic capacitor

Electrolytic capacitor

An electrolytic capacitor is a type of capacitor that uses an electrolyte, an ionic conducting liquid, as one of its plates, to achieve a larger capacitance per unit volume than other types. They are often referred to in electronics usage simply as "electrolytics"...

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Electromagnetic environment

Electromagnetic environment

In telecommunication, the term electromagnetic environment has the following meanings:#For a telecommunications system, the spatial distribution of electromagnetic fields surrounding a given site...

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Electromagnetic induction

Electromagnetic induction

Electromagnetic induction is the production of an electric current across a conductor moving through a magnetic field. It underlies the operation of generators, transformers, induction motors, electric motors, synchronous motors, and solenoids....

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Electromagnetic interference control

Electromagnetic interference control

In telecommunication, electromagnetic interference control is the control of radiated and conducted energy such that emissions that are unnecessary for system, subsystem, or equipment operation are reduced, minimized, or eliminated....

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Electromagnetic pulse

Electromagnetic pulse

An electromagnetic pulse is a burst of electromagnetic radiation. The abrupt pulse of electromagnetic radiation usually results from certain types of high energy explosions, especially a nuclear explosion, or from a suddenly fluctuating magnetic field...

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Electromagnetic radiation and health –
Electromagnetic radiation

Electromagnetic radiation

Electromagnetic radiation is a form of energy that exhibits wave-like behavior as it travels through space...

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Electromagnetic spectrum

Electromagnetic spectrum

The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation. The "electromagnetic spectrum" of an object is the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object....

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Electromagnetic survivability

Electromagnetic survivability

In telecommunication, electromagnetic survivability is the ability of a system, subsystem, or equipment to resume functioning without evidence of degradation following temporary exposure to an adverse electromagnetic environment....

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Electromagnetism

Electromagnetism

Electromagnetism is one of the four fundamental interactions in nature. The other three are the strong interaction, the weak interaction and gravitation...

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Electrometer

Electrometer

An electrometer is an electrical instrument for measuring electric charge or electrical potential difference. There are many different types, ranging from historical hand-made mechanical instruments to high-precision electronic devices...

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Electron hole

Electron hole

An electron hole is the conceptual and mathematical opposite of an electron, useful in the study of physics, chemistry, and electrical engineering. The concept describes the lack of an electron at a position where one could exist in an atom or atomic lattice...

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Electron

Electron

The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...

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Electronic amplifier

Electronic amplifier

An electronic amplifier is a device for increasing the power of a signal.It does this by taking energy from a power supply and controlling the output to match the input signal shape but with a larger amplitude...

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Electronic color code

Electronic color code

The electronic color code is used to indicate the values or ratings of electronic components, very commonly for resistors, but also for capacitors, inductors, and others...

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Color code

Electronic color code

The electronic color code is used to indicate the values or ratings of electronic components, very commonly for resistors, but also for capacitors, inductors, and others...

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Electronic deception

Electronic deception

In telecommunication, the term electronic deception means the deliberate radiation, reradiation, alteration, suppression, absorption, denial, enhancement, or reflection of electromagnetic energy in a manner intended to convey misleading information and to deny valid information to an enemy or to...

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Electronic design automation

Electronic design automation

Electronic design automation is a category of software tools for designing electronic systems such as printed circuit boards and integrated circuits...

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Electronic filter

Electronic filter

Electronic filters are electronic circuits which perform signal processing functions, specifically to remove unwanted frequency components from the signal, to enhance wanted ones, or both...

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Filter

Electronic filter

Electronic filters are electronic circuits which perform signal processing functions, specifically to remove unwanted frequency components from the signal, to enhance wanted ones, or both...

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Electronic imager

Electronic imager

An electronic imager is an electronic device that detects electromagnetic radiation with spatial resolution. It is the electronic analog of the photographic plate or film. Common applications are digital photography and astrophotography....

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Electronic mixer

Electronic mixer

An electronic mixer is a device that combines two or more electrical or electronic signals into one or two composite output signals. There are two basic circuits that both use the term mixer, but they are very different types of circuits: additive mixers and multiplying mixers...

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Electronic musical instrument

Electronic musical instrument

An electronic musical instrument is a musical instrument that produces its sounds using electronics. Such an instrument sounds by outputting an electrical audio signal that ultimately drives a loudspeaker....

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Electronic oscillator

Electronic oscillator

An electronic oscillator is an electronic circuit that produces a repetitive electronic signal, often a sine wave or a square wave. They are widely used in innumerable electronic devices...

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Electronic power supply –
Electronic switching system

Electronic switching system

In telecommunications, an electronic switching system is:* A telephone exchange based on the principles of time-division multiplexing of digitized analog signals. An electronic switching system digitizes analog signals from subscriber loops, and interconnects them by assigning the digitized...

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Electronic tagging

Electronic tagging

Electronic tagging is a form of non-surreptitious surveillance consisting of an electronic device attached to a person or vehicle, especially certain criminals, allowing their whereabouts to be monitored. In general, devices locate themselves using GPS and report their position back to a control...

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Electronic test equipment

Electronic test equipment

Electronic test equipment is used to create signals and capture responses from electronic Devices Under Test . In this way, the proper operation of the DUT can be proven or faults in the device can be traced and repaired...

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Electronic warfare support measures

Electronic warfare support measures

In military telecommunications, the terms Electronic Support or Electronic Support Measures describe the division of electronic warfare involving actions taken under direct control of an operational commander to detect, intercept, identify, locate, record, and/or analyze sources of radiated...

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Electronics

Electronics

Electronics is the branch of science, engineering and technology that deals with electrical circuits involving active electrical components such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive interconnection technologies...

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Electro-optic effect

Electro-optic effect

An electro-optic effect is a change in the optical properties of a material in response to an electric field that varies slowly compared with the frequency of light...

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Electro-optic modulator

Electro-optic modulator

Electro-optic modulator is an optical device in which a signal-controlled element displaying electro-optic effect is used to modulate a beam of light. The modulation may be imposed on the phase, frequency, amplitude, or polarization of the modulated beam...

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Electro-optics

Electro-optics

Electro-optics is a branch of technology involving components, devices and systems which operate by modification of the optical properties of a material by an electric field...

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Electrostatic discharge

Electrostatic discharge

Electrostatic discharge is a serious issue in solid state electronics, such as integrated circuits. Integrated circuits are made from semiconductor materials such as silicon and insulating materials such as silicon dioxide...

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Electrostatics

Electrostatics

Electrostatics is the branch of physics that deals with the phenomena and properties of stationary or slow-moving electric charges....

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Emergency Locator Transmitter –
Emergency Position-Indicating Radio Beacon

Emergency Position-Indicating Radio Beacon

Distress radio beacons, also known as emergency beacons, ELT or EPIRB, are tracking transmitters which aid in the detection and location of boats, aircraft, and people in distress. Strictly, they are radiobeacons that interface with worldwide offered service of Cospas-Sarsat, the international...

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Emitter coupled logic

Emitter coupled logic

In electronics, emitter-coupled logic , is a logic family that achieves high speed by using an overdriven BJT differential amplifier with single-ended input, whose emitter current is limited to avoid the slow saturation region of transistor operation....

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End distortion

End distortion

End distortion: In start-stop teletypewriter operation, the shifting of the end of all marking pulses, except the stop pulse, from their proper positions in relation to the beginning of the next start pulse....

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Endurability

Endurability

In telecommunication, endurability is the property of a system, subsystem, equipment, or process that enables it to continue to function within specified performance limits for an extended period of time, usually months, despite a severe natural or man-made disturbance, such as a nuclear attack, or...

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Enhanced service

Enhanced service

Enhanced service is service offered over commercial carrier transmission facilities used in interstate communications, that employs computer processing applications that act on the format, content, code, protocol, or similar aspects of the subscriber's transmitted information; provides the...

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Entropy encoding

Entropy encoding

In information theory an entropy encoding is a lossless data compression scheme that is independent of the specific characteristics of the medium....

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Equilibrium length –
Equivalent impedance transforms

Equivalent impedance transforms

An equivalent impedance is an equivalent circuit of an electrical network of impedance elements which presents the same impedance between all pairs of terminals as did the given network...

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Equivalent noise resistance –
Equivalent pulse code modulation noise

Equivalent pulse code modulation noise

In telecommunication, equivalent pulse code modulation noise is the amount of thermal noise power on a frequency-division multiplexing or wire channel necessary to approximate the same judgment of speech quality created by quantizing noise in a PCM channel....

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Error burst

Error burst

In telecommunication, a burst error or error burst is a contiguous sequence of symbols, received over a data transmission channel, such that the first and last symbols are in error and there exists no contiguous subsequence of m correctly received symbols within the error burst.The integer...

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Error ratio –
Error-correcting code –
E-skip –
Examples of electrical phenomena –
Extremely Low Frequency

Extremely low frequency

Extremely low frequency is a term used to describe radiation frequencies from 3 to 300 Hz. In atmosphere science, an alternative definition is usually given, from 3 Hz to 3 kHz...

 (ELF) –
Eye pattern

Eye pattern

In telecommunication, an eye pattern, also known as an eye diagram, is an oscilloscope display in which a digital data signal from a receiver is repetitively sampled and applied to the vertical input, while the data rate is used to trigger the horizontal sweep...

F

Fab (semiconductors) –
Semiconductor device fabrication –
Facsimile converter

Facsimile converter

In telecommunication, the term facsimile converter has the following meanings:1. In a facsimile receiver, a device that changes the signal modulation from frequency-shift keying to amplitude modulation ....

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Fading

Fading

In wireless communications, fading is deviation of the attenuation that a carrier-modulated telecommunication signal experiences over certain propagation media. The fading may vary with time, geographical position and/or radio frequency, and is often modelled as a random process. A fading channel...

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Fading distribution

Fading distribution

In telecommunications, a fading distribution is the probability distribution of the value of signal fading relative to a specified reference level....

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Fail safe –
Fall time

Fall time

In electronics, fall time \scriptstyle t_f\, is the time required for the amplitude of a pulse to decrease from a specified value to another specified value...

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Fan-beam antenna

Fan-beam antenna

A fan-beam antenna is a directional antenna producing a main beam having a narrow beamwidth in one dimension and a wider beamwidth in the other dimension. This pattern will be achieved by a truncated paraboloid reflector or a circular paraboloid reflector...

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Farad

Farad

The farad is the SI unit of capacitance. The unit is named after the English physicist Michael Faraday.- Definition :A farad is the charge in coulombs which a capacitor will accept for the potential across it to change 1 volt. A coulomb is 1 ampere second...

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Faraday cage

Faraday cage

A Faraday cage or Faraday shield is an enclosure formed by conducting material or by a mesh of such material. Such an enclosure blocks out external static and non-static electric fields...

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Faraday constant –
Faraday's law of induction

Faraday's law of induction

Faraday's law of induction dates from the 1830s, and is a basic law of electromagnetism relating to the operating principles of transformers, inductors, and many types of electrical motors and generators...

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Far-field region –
Fault management

Fault management

In network management, fault management is the set of functions that detect, isolate, and correct malfunctions in a telecommunications network, compensate for environmental changes, and include maintaining and examining error logs, accepting and acting on error detection notifications, tracing and...

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Fault –
FCC registration program

FCC registration program

In telecommunication, FCC registration program is the Federal Communications Commission program and associated directives intended to assure that all connected terminal equipment and protective circuitry will not harm the public switched telephone network or certain private line services.Note 1: ...

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Federal Standard 1037C

Federal Standard 1037C

Federal Standard 1037C, titled Telecommunications: Glossary of Telecommunication Terms is a United States Federal Standard, issued by the General Services Administration pursuant to the Federal Property and Administrative Services Act of 1949, as amended....

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Feed horn

Feed horn

In satellite dish and antenna design, a feedhorn is a small horn antenna used to convey radio waves between the transmitter and/or receiver and the reflector, particularly in parabolic antennas...

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Feedback

Feedback

Feedback describes the situation when output from an event or phenomenon in the past will influence an occurrence or occurrences of the same Feedback describes the situation when output from (or information about the result of) an event or phenomenon in the past will influence an occurrence or...

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Ferroelectric effect –
Ferromagnetism

Ferromagnetism

Ferromagnetism is the basic mechanism by which certain materials form permanent magnets, or are attracted to magnets. In physics, several different types of magnetism are distinguished...

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Field (physics)

Field (physics)

In physics, a field is a physical quantity associated with each point of spacetime. A field can be classified as a scalar field, a vector field, a spinor field, or a tensor field according to whether the value of the field at each point is a scalar, a vector, a spinor or, more generally, a tensor,...

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Field

Field (video)

In video, a field is one of the many still images which are displayed sequentially to create the impression of motion on the screen. Two fields comprise one video frame...

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Field effect transistor –
Field strength

Field strength

In physics, the field strength of a field is the magnitude of its vector value.In theoretical physics, field strength is another name for the curvature form...

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FPGA Field programmable gate array

Field-programmable gate array

A field-programmable gate array is an integrated circuit designed to be configured by the customer or designer after manufacturing—hence "field-programmable"...

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Filled cable

Filled cable

In telecommunication, a filled cable is a cable that has a nonhygroscopic material, usually a gel called icky-pick, inside the jacket or sheath....

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Filter design

Filter design

Filter design is the process of designing a filter , often a linear shift-invariant filter, that satisfies a set of requirements, some of which are contradictory...

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Filter (signal processing)

Filter (signal processing)

In signal processing, a filter is a device or process that removes from a signal some unwanted component or feature. Filtering is a class of signal processing, the defining feature of filters being the complete or partial suppression of some aspect of the signal...

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Flip-flop

Flip-flop (electronics)

In electronics, a flip-flop or latch is a circuit that has two stable states and can be used to store state information. The circuit can be made to change state by signals applied to one or more control inputs and will have one or two outputs. It is the basic storage element in sequential logic...

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Fluorescent lamp

Fluorescent lamp

A fluorescent lamp or fluorescent tube is a gas-discharge lamp that uses electricity to excite mercury vapor. The excited mercury atoms produce short-wave ultraviolet light that then causes a phosphor to fluoresce, producing visible light. A fluorescent lamp converts electrical power into useful...

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Flutter –
Flux

Flux

In the various subfields of physics, there exist two common usages of the term flux, both with rigorous mathematical frameworks.* In the study of transport phenomena , flux is defined as flow per unit area, where flow is the movement of some quantity per time...

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Flywheel effect

Flywheel effect

The flywheel effect is the continuation of oscillations in an oscillator circuit after the control stimulus has been removed. This is usually caused by interacting inductive and capacitive elements in the oscillator...

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FM band –
FM improvement factor –
FM improvement threshold –
FM radio –
Forward error correction

Forward error correction

In telecommunication, information theory, and coding theory, forward error correction or channel coding is a technique used for controlling errors in data transmission over unreliable or noisy communication channels....

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Fourier series

Fourier series

In mathematics, a Fourier series decomposes periodic functions or periodic signals into the sum of a set of simple oscillating functions, namely sines and cosines...

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Fourier transform

Fourier transform

In mathematics, Fourier analysis is a subject area which grew from the study of Fourier series. The subject began with the study of the way general functions may be represented by sums of simpler trigonometric functions...

 (see also List of Fourier-related transforms) –
Four-wire circuit

Four-wire circuit

In telecommunication, a four-wire circuit is a two-way circuit using two paths so arranged that the respective signals are transmitted in one direction only by one path and in the other direction by the other path...

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Four-wire terminating set

Four-wire terminating set

A four-wire terminating set is a balanced transformer used to perform a conversion between 4-wire and 2-wire operation in telecommunication systems.For example, a 4-wire circuit may, by means of a 4-wire terminating set, be connected to a 2-wire telephone set...

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Fractal antenna

Fractal antenna

A fractal antenna is an antenna that uses a fractal, self-similar design to maximize the length, or increase the perimeter , of material that can receive or transmit electromagnetic radiation within a given total surface area or volume.Such fractal antennas are also referred to as multilevel and...

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Frame –
Frame rate

Frame rate

Frame rate is the frequency at which an imaging device produces unique consecutive images called frames. The term applies equally well to computer graphics, video cameras, film cameras, and motion capture systems...

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Frame slip

Frame slip

In the reception of framed data, a frame slip is the loss of synchronization between a received frame and the receiver clock signal, causing a frame misalignment event, and resulting in the loss of the data contained in the received frame....

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Frame synchronization

Frame synchronization

While receiving a stream of framed data, frame synchronization is the process by which incoming frame alignment signals, i.e., distinctive bit sequences , are identified, i.e., distinguished from data bits, permitting the data bits within the frame to be extracted for decoding or retransmission...

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Framing bit –
Freenet

Freenet

Freenet is a decentralized, censorship-resistant distributed data store originally designed by Ian Clarke. According to Clarke, Freenet aims to provide freedom of speech through a peer-to-peer network with strong protection of anonymity; as part of supporting its users' freedom, Freenet is free and...

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Free-space loss

Free-space loss

In telecommunication, free-space path loss is the loss in signal strength of an electromagnetic wave that would result from a line-of-sight path through free space , with no obstacles nearby to cause reflection or diffraction...

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Freeze frame television

Freeze frame television

Freeze frame television: Television in which fixed images are transmitted sequentially at a rate far too slow to be perceived as continuous motion by human vision...

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Frequency assignment –
Frequency averaging

Frequency averaging

In telecommunication, the term frequency averaging has the following meanings:#The process by which the relative phases of precision clocks are compared for the purpose of defining a single time standard....

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Frequency counter

Frequency counter

A frequency counter is an electronic instrument, or component of one, that is used for measuring frequency. Frequency is defined as the number of events of a particular sort occurring in a set period of time. Frequency counters usually measure the number of oscillations or pulses per second in a...

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Frequency deviation

Frequency deviation

Frequency deviation is used in FM radio to describe the maximum instantaneous difference between an FM modulated frequency and the nominal carrier frequency...

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Frequency frogging

Frequency frogging

In telecommunication, the term frequency frogging has the following meanings:# The interchanging of the frequencies of carrier channels to accomplish specific purposes, such as to prevent feedback and oscillation, to reduce crosstalk, and to correct for a high frequency response slope in the...

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Frequency modulation synthesis

Frequency modulation synthesis

A 220 Hz carrier tone modulated by a 440 Hz modulating tone with various choices of modulation index, β. The time domain signals are illustrated above, and the corresponding spectra are shown below ....

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Frequency modulation

Frequency modulation

In telecommunications and signal processing, frequency modulation conveys information over a carrier wave by varying its instantaneous frequency. This contrasts with amplitude modulation, in which the amplitude of the carrier is varied while its frequency remains constant...

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Frequency standard

Frequency standard

A frequency standard is a stable oscillator used for frequency calibration or reference. A frequency standard generates a fundamental frequency with a high degree of accuracy and precision. Harmonics of this fundamental frequency are used to provide reference points.Since time is the reciprocal of...

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Frequency synthesiser –
Frequency

Frequency

Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency...

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Frequency-division multiplexing

Frequency-division multiplexing

Frequency-division multiplexing is a form of signal multiplexing which involves assigning non-overlapping frequency ranges to different signals or to each "user" of a medium.- Telephone :...

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Frequency-exchange signaling

Frequency-exchange signaling

Frequency-exchange signaling is frequency-change signaling in which the change from one significant condition to another is accompanied by decay in amplitude of one or more frequencies and by buildup in amplitude of one or more other frequencies....

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Frequency-hopping spread spectrum

Frequency-hopping spread spectrum

Frequency-hopping spread spectrum is a method of transmitting radio signals by rapidly switching a carrier among many frequency channels, using a pseudorandom sequence known to both transmitter and receiver...

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Frequency-shift keying

Frequency-shift keying

Frequency-shift keying is a frequency modulation scheme in which digital information is transmitted through discrete frequency changes of a carrier wave. The simplest FSK is binary FSK . BFSK uses a pair of discrete frequencies to transmit binary information. With this scheme, the "1" is called...

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Fresnel equations

Fresnel equations

The Fresnel equations , deduced by Augustin-Jean Fresnel , describe the behaviour of light when moving between media of differing refractive indices...

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Fresnel reflection –
Fresnel zone

Fresnel zone

In optics and radio communications , a Fresnel zone , named for physicist Augustin-Jean Fresnel, is one of a number of concentric ellipsoids which define volumes in the radiation pattern of a circular aperture...

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Front-to-back ratio

Front-to-back ratio

In telecommunication, the term front-to-back ratio can mean:#The ratio of power gain between the front and rear of a directional antenna....

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Fuel cell

Fuel cell

A fuel cell is a device that converts the chemical energy from a fuel into electricity through a chemical reaction with oxygen or another oxidizing agent. Hydrogen is the most common fuel, but hydrocarbons such as natural gas and alcohols like methanol are sometimes used...

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Fuse (electrical)

Fuse (electrical)

In electronics and electrical engineering, a fuse is a type of low resistance resistor that acts as a sacrificial device to provide overcurrent protection, of either the load or source circuit...

G

Gallium arsenide –
Galvanometer

Galvanometer

A galvanometer is a type of ammeter: an instrument for detecting and measuring electric current. It is an analog electromechanical transducer that produces a rotary deflection of some type of pointer in response to electric current flowing through its coil in a magnetic field. .Galvanometers were...

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Garble

Garble

Garble is a blogging system based on the Jasper web programming framework. It also supports Facebook integration via the About Face theme.- External links :* * for the word garble, see wikt:garble...

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Gateway

Gateway (telecommunications)

In telecommunications, the term gateway has the following meaning:*In a communications network, a network node equipped for interfacing with another network that uses different protocols....

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Gating

Gating signal

A digital signal or pulse that provides a time window so that a particular event or signal from among many will be selected and others will be eliminated or discarded....

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Gauss

Gauss (unit)

The gauss, abbreviated as G, is the cgs unit of measurement of a magnetic field B , named after the German mathematician and physicist Carl Friedrich Gauss. One gauss is defined as one maxwell per square centimeter; it equals 1 tesla...

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Geiger-Mueller tube –
Gel electrophoresis

Gel electrophoresis

Gel electrophoresis is a method used in clinical chemistry to separate proteins by charge and or size and in biochemistry and molecular biology to separate a mixed population of DNA and RNA fragments by length, to estimate the size of DNA and RNA fragments or to separate proteins by charge...

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Gemini Guidance Computer –
Gender changer

Gender changer

A gender changer is a hardware device placed between two cable connectors of the same type and gender.An example is a cable connector shell with either two female or two male connectors on it , used to correct the mismatches that result when interconnecting two devices or cables with the same...

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Global Positioning System

Global Positioning System

The Global Positioning System is a space-based global navigation satellite system that provides location and time information in all weather, anywhere on or near the Earth, where there is an unobstructed line of sight to four or more GPS satellites...

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Global system for mobile communications

Global System for Mobile Communications

GSM , is a standard set developed by the European Telecommunications Standards Institute to describe technologies for second generation digital cellular networks...

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GNU Radio

GNU Radio

GNU Radio is a free software toolkit for learning about, building, and deploying software-defined radio systems. GNU Radio is released under the GPL version 3 license....

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Grade of service

Grade of service

In telecommunication engineering, and in particular teletraffic engineering, the quality of voice service is specified by two measures: the grade of service and the quality of service ....

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Graded-index fiber

Graded-index fiber

In fiber optics, a graded-index or gradient-index fiber is an optical fiber whose core has a refractive index that decreases with increasing radial distance from the fiber axis ....

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Ground constants

Ground constants

In telecommunication, ground constants are the electrical parameters of earth, such as conductivity, permittivity, and magnetic permeability.The values of these parameters vary with the local chemical composition and density of the Earth...

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Ground loop

Ground loop (electricity)

In an electrical system, a ground loop usually refers to a current, almost always unwanted, in a conductor connecting two points that are supposed to be at the same potential, often ground, but are actually at different potentials. Ground loops created by improperly designed or improperly installed...

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Ground plane

Ground plane

In electrical engineering, a ground plane is an electrically conductive surface.-Radio antenna theory :In telecommunication, a ground plane structure or relationship exists between the antenna and another object, where the only structure of the object is a structure which permits the antenna to...

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Ground (electricity)

Ground (electricity)

In electrical engineering, ground or earth may be the reference point in an electrical circuit from which other voltages are measured, or a common return path for electric current, or a direct physical connection to the Earth....

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Groundwave –
Guided ray –
Gyrator

Gyrator

A gyrator is a passive, linear, lossless, two-port electrical network element proposed in 1948 by Tellegen as a hypothetical fifth linear element after the resistor, capacitor, inductor and ideal transformer. Unlike the four conventional elements, the gyrator is non-reciprocal...

H

Halftone characteristic

Halftone characteristic

In telecommunication, the term halftone characteristic has the following meanings:# In facsimile systems, the relationship between the density of the recorded copy and the density of the object, i.e., the original....

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Hall effect

Hall effect

The Hall effect is the production of a voltage difference across an electrical conductor, transverse to an electric current in the conductor and a magnetic field perpendicular to the current...

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Hamming code

Hamming code

In telecommunication, Hamming codes are a family of linear error-correcting codes that generalize the Hamming-code invented by Richard Hamming in 1950. Hamming codes can detect up to two and correct up to one bit errors. By contrast, the simple parity code cannot correct errors, and can detect only...

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Hamming distance

Hamming distance

In information theory, the Hamming distance between two strings of equal length is the number of positions at which the corresponding symbols are different...

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Handoff –
Handshaking

Handshaking

In information technology, telecommunications, and related fields, handshaking is an automated process of negotiation that dynamically sets parameters of a communications channel established between two entities before normal communication over the channel begins...

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Hard copy

Hard copy

In information handling, a hard copy is a permanent reproduction, or copy, in the form of a physical object, of any media suitable for direct use by a person , of displayed or transmitted data...

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Hardware register

Hardware register

In digital electronics, especially computing, a hardware register stores bits of information, in a way that all the bits can be written to or read out simultaneously.The hardware registers inside a central processing unit are called processor registers....

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Harmonic analysis

Harmonic analysis

Harmonic analysis is the branch of mathematics that studies the representation of functions or signals as the superposition of basic waves. It investigates and generalizes the notions of Fourier series and Fourier transforms...

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Harmonic oscillator

Harmonic oscillator

In classical mechanics, a harmonic oscillator is a system that, when displaced from its equilibrium position, experiences a restoring force, F, proportional to the displacement, x: \vec F = -k \vec x \, where k is a positive constant....

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Harmonic

Harmonic

A harmonic of a wave is a component frequency of the signal that is an integer multiple of the fundamental frequency, i.e. if the fundamental frequency is f, the harmonics have frequencies 2f, 3f, 4f, . . . etc. The harmonics have the property that they are all periodic at the fundamental...

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Hartley oscillator

Hartley oscillator

The Hartley oscillator is an electronic oscillator circuit that uses an inductor and a capacitor in parallel to determine the frequency. Invented in 1915 by American engineer Ralph Hartley, the distinguishing feature of the Hartley circuit is that the feedback needed for oscillation is taken from...

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H-channel

H-channel

In the Integrated Services Digital Network , a high-speed channel comprising multiple aggregated low-speed channels to accommodate bandwidth-intensive applications such as file transfer, videoconferencing, and high-quality audio...

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Heat sink

Heat sink

A heat sink is a term for a component or assembly that transfers heat generated within a solid material to a fluid medium, such as air or a liquid. Examples of heat sinks are the heat exchangers used in refrigeration and air conditioning systems and the radiator in a car...

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Helical antenna

Helical antenna

A helical antenna is an antenna consisting of a conducting wire wound in the form of a helix. In most cases, helical antennas are mounted over a ground plane. The feed line is connected between the bottom of the helix and the ground plane...

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Helmholtz coil

Helmholtz coil

A Helmholtz coil is a device for producing a region of nearly uniform magnetic field. It is named in honor of the German physicist Hermann von Helmholtz.- Description :A Helmholtz pair consists of two identical circular magnetic...

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Henry (unit) –
Hertz

Hertz

The hertz is the SI unit of frequency defined as the number of cycles per second of a periodic phenomenon. One of its most common uses is the description of the sine wave, particularly those used in radio and audio applications....

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Heterodyne repeater –
Heterodyne

Heterodyne

Heterodyning is a radio signal processing technique invented in 1901 by Canadian inventor-engineer Reginald Fessenden where high frequency signals are converted to lower frequencies by combining two frequencies. Heterodyning is useful for frequency shifting information of interest into a useful...

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High frequency

High frequency

High frequency radio frequencies are between 3 and 30 MHz. Also known as the decameter band or decameter wave as the wavelengths range from one to ten decameters . Frequencies immediately below HF are denoted Medium-frequency , and the next higher frequencies are known as Very high frequency...

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High-performance equipment

High-performance equipment

High-performance equipment describes telecommunications equipment that has the performance characteristics required for use in trunks or links, is designed primarily for use in global and tactical systems, and sufficiently withstands electromagnetic interference when operating in a variety of...

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High-speed circuit-switched data

High-Speed Circuit-Switched Data

High-speed circuit-switched data , is an enhancement to Circuit Switched Data , the original data transmission mechanism of the GSM mobile phone system, four times faster than GSM, with data rates up to 38.4 kbit/s....

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Hop

Hop (telecommunications)

In telecommunication, the term hop has the following meanings:#The excursion of a radio wave from the Earth to the ionosphere and back to the Earth...

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Horn

Horn (telecommunications)

A horn antenna or microwave horn is an antenna that consists of a flaring metal waveguide shaped like a horn to direct the radio waves. Horns are widely used as antennas at UHF and microwave frequencies, above 300 MHz...

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How to test three-phase electrical supply –
How to test three-phase pumps –
Hybrid balance

Hybrid balance

In telecommunications, a hybrid balance is an expression of the degree of electrical symmetry between two impedances connected to two conjugate sides of a hybrid coil or resistance hybrid.Note 1: Hybrid balance is usually expressed in dB....

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Hybrid circuit

Hybrid circuit

A hybrid integrated circuit, HIC, hybrid microcircuit, or simply hybrid is a miniaturized electronic circuit constructed of individual devices, such as semiconductor devices and passive components , bonded to a substrate or printed circuit board...

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Hybrid coil

Hybrid coil

A hybrid coil is a transformer that has three windings, and which is designed to be configured as a circuit having four branches, that are conjugate in pairs....

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Hybrid coupler

Hybrid coupler

A hybrid coupler is a passive device used in radio and telecommunications. It is a type of directional coupler where the input power is equally divided between two output ports. Since it is a special case of directional coupler, it is discussed in Power dividers and directional...

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Hysteresis

Hysteresis

Hysteresis is the dependence of a system not just on its current environment but also on its past. This dependence arises because the system can be in more than one internal state. To predict its future evolution, either its internal state or its history must be known. If a given input alternately...

I

IEEE 315-1975 -
IEEE 802.11

IEEE 802.11

IEEE 802.11 is a set of standards for implementing wireless local area network computer communication in the 2.4, 3.6 and 5 GHz frequency bands. They are created and maintained by the IEEE LAN/MAN Standards Committee . The base version of the standard IEEE 802.11-2007 has had subsequent...

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IEEE 802.15

IEEE 802.15

IEEE 802.15 is a working group of the Institute of Electrical and Electronics Engineers IEEE 802 standards committee which specifies wireless personal area network standards. It includes seven task groups.-Task group 1 :...

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IEEE 802

IEEE 802

IEEE 802 refers to a family of IEEE standards dealing with local area networks and metropolitan area networks.More specifically, the IEEE 802 standards are restricted to networks carrying variable-size packets. IEEE 802 refers to a family of IEEE standards dealing with local area networks and...

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Image antenna

Image antenna

In telecommunications and antenna design, an image antenna is an electrical mirror-image of an antenna element formed by the radio waves reflecting from a conductive surface called a ground plane, such as the surface of the earth...

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Image impedance

Image impedance

Image impedance is a concept used in electronic network design and analysis and most especially in filter design. The term image impedance applies to the impedance seen looking in to the ports of a network. Usually a two-port network is implied but the concept is capable of being extended to...

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Image frequency –
Image rejection ratio

Image rejection ratio

In radio, the image rejection ratio, or image frequency rejection ratio, is the ratio of the intermediate-frequency signal level produced by the desired input frequency to that produced by the image frequency. The image rejection ratio is usually expressed in dB...

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Image response

Image response

Image response is a measure of performance of a radio receiver, particularly one that operates on the super-heterodyne principle....

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Impedance matching

Impedance matching

In electronics, impedance matching is the practice of designing the input impedance of an electrical load to maximize the power transfer and/or minimize reflections from the load....

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In-band on-channel

In-band on-channel

In-band on-channel is a hybrid method of transmitting digital radio and analog radio broadcast signals simultaneously on the same frequency....

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Incidental radiator –
Independent sideband

Independent sideband

Independent sideband is an AM single sideband mode which is used with some AM radio transmissions. Normally each sideband carries identical information, but ISB modulates two different input signals — one on the upper sideband, the other on the lower sideband...

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Index of cooperation

Index of cooperation

In telecommunication, the term index of cooperation has the following meanings:...

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Inductive coupling

Inductive coupling

In electrical engineering, two conductors are referred to as mutual-inductively coupled or magnetically coupled when they are configured such that change in current flow through one wire induces a voltage across the ends of the other wire through electromagnetic induction...

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Inductive reactance –
Inductor

Inductor

An inductor is a passive two-terminal electrical component used to store energy in a magnetic field. An inductor's ability to store magnetic energy is measured by its inductance, in units of henries...

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Industrial Computers -
Information transfer

Information transfer

In telecommunications, information transfer is the process of moving messages containing user information from a source to a sink.Note: The information transfer rate may or may not be equal to the transmission modulation rate.-See also:...

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Information-bearer channel

Information-bearer channel

In telecommunication, the term information-bearer channel has the following meanings:1. A channel capable of transmitting all the information required for communication, such as user data, synchronizing sequences, and control signals....

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Infrared

Infrared

Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...

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Input/output

Input/output

In computing, input/output, or I/O, refers to the communication between an information processing system , and the outside world, possibly a human, or another information processing system. Inputs are the signals or data received by the system, and outputs are the signals or data sent from it...

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Insertion gain

Insertion gain

In telecommunication, insertion gain is the gain resulting from the insertion of a device in a transmission line, expressed as the ratio of the signal power delivered to that part of the line following the device to the signal power delivered to that same part before insertion...

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Insertion loss

Insertion loss

In telecommunications, insertion loss is the loss of signal power resulting from the insertion of a device in a transmission line or optical fiber and is usually expressed in decibels ....

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Inside plant

Inside plant

In telecommunication, the term inside plant has the following meanings:*All the cabling and equipment installed in a telecommunications facility, including the main distribution frame and all the equipment extending inward therefrom, such as PABX or central office equipment, MDF heat coil...

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Integrated circuit

Integrated circuit

An integrated circuit or monolithic integrated circuit is an electronic circuit manufactured by the patterned diffusion of trace elements into the surface of a thin substrate of semiconductor material...

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Intensity modulation

Intensity modulation

In optical communications, intensity modulation is a form of modulation in which the optical power output of a source is varied in accordance with some characteristic of the modulating signal....

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Intentional radiator

Intentional radiator

An intentional radiator is any device that is designed to produce radio waves on purpose.Radio transmitters of all kinds, including the garage door opener, cordless telephone, cellular phone, wireless video sender, wireless microphone, and many others fall into this category.-See also:* incidental...

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Intercept

Telephone tapping

Telephone tapping is the monitoring of telephone and Internet conversations by a third party, often by covert means. The wire tap received its name because, historically, the monitoring connection was an actual electrical tap on the telephone line...

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Interchange circuit

Interchange circuit

In telecommunication, an interchange circuit is a circuit that facilitates the exchange of data and signaling information between data terminal equipment and data circuit-terminating equipment ....

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Intercharacter interval

Intercharacter interval

In telecommunications, the intercharacter interval is the time interval between the end of the stop signal of one character and the beginning of the start signal of the next character of an asynchronous transmission....

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Interconnect facility

Interconnect facility

Interconnect facility: In a communications network, one or more communications links that are used to provide local area communications service among several locations and collectively form a node in the network....

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Interference

Interference (communication)

In communications and electronics, especially in telecommunications, interference is anything which alters, modifies, or disrupts a signal as it travels along a channel between a source and a receiver. The term typically refers to the addition of unwanted signals to a useful signal...

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Interferometry

Interferometry

Interferometry refers to a family of techniques in which electromagnetic waves are superimposed in order to extract information about the waves. An instrument used to interfere waves is called an interferometer. Interferometry is an important investigative technique in the fields of astronomy,...

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Intermediate-field region

Intermediate-field region

Intermediate-field region: For an antenna, the transition region--lying between the near-field region and the far-field region--in which the field strength of an electromagnetic wave is dependent upon the inverse distance, inverse square of the distance, and the inverse cube of the distance from...

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Intermodulation distortion –
International Electrotechnical Commission

International Electrotechnical Commission

The International Electrotechnical Commission is a non-profit, non-governmental international standards organization that prepares and publishes International Standards for all electrical, electronic and related technologies – collectively known as "electrotechnology"...

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Interoperability

Interoperability

Interoperability is a property referring to the ability of diverse systems and organizations to work together . The term is often used in a technical systems engineering sense, or alternatively in a broad sense, taking into account social, political, and organizational factors that impact system to...

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Interposition trunk

Interposition trunk

In telecommunication, the term interposition trunk has the following meanings:1. A single direct transmission channel, e.g., voice-frequency circuit, between two positions of a large switchboard to facilitate the interconnection of other circuits appearing at the respective switchboard...

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Intersymbol interference

Intersymbol interference

In telecommunication, intersymbol interference is a form of distortion of a signal in which one symbol interferes with subsequent symbols. This is an unwanted phenomenon as the previous symbols have similar effect as noise, thus making the communication less reliable...

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Inverse multiplexer

Inverse multiplexer

An inverse multiplexer allows a data stream to be broken into multiple lower data rate communication links. An inverse multiplexer differs from a demultiplexer because the multiple output streams from the former stay inter-related, whereas those from the latter are unrelated...

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Inverse-square law

Inverse-square law

In physics, an inverse-square law is any physical law stating that a specified physical quantity or strength is inversely proportional to the square of the distance from the source of that physical quantity....

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Ion pump –
Ionosphere

Ionosphere

The ionosphere is a part of the upper atmosphere, comprising portions of the mesosphere, thermosphere and exosphere, distinguished because it is ionized by solar radiation. It plays an important part in atmospheric electricity and forms the inner edge of the magnetosphere...

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ISM band

ISM band

The industrial, scientific and medical radio bands are radio bands reserved internationally for the use of radio frequency energy for industrial, scientific and medical purposes other than communications....

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Isochronous burst transmission

Isochronous burst transmission

Isochronous burst transmission is a method of data transmission. In a data network where the information-bearer channel rate is higher than the input data signaling rate, transmission is performed by interrupting, at controlled intervals, the data stream being transmitted.Note 1: Isochronous...

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Isochronous signal

Isochronous signal

In telecommunication, an isochronous signal is a signal in which the time interval separating any two significant instants is equal to the unit interval or a multiple of the unit interval....

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Isotropic antenna

K

Karnaugh map

Karnaugh map

The Karnaugh map , Maurice Karnaugh's 1953 refinement of Edward Veitch's 1952 Veitch diagram, is a method to simplify Boolean algebra expressions...

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Kendall effect

Kendall effect

In telecommunications the Kendall effect is a spurious pattern or other distortion in a facsimile.It is caused by unwanted modulation products which arise from the transmission of the carrier signal, and appear in the form of a rectified baseband that interferes with the lower sideband of the...

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Key pulsing –
K-factor

K-factor (telecommunications)

In telecommunication, the term k-factor has the following meanings:# In tropospheric radio propagation, the ratio of the effective Earth radius to the actual Earth radius...

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Kirchhoff's circuit laws

Kirchhoff's circuit laws

Kirchhoff's circuit laws are two equalities that deal with the conservation of charge and energy in electrical circuits, and were first described in 1845 by Gustav Kirchhoff...

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Klystron

Klystron

A klystron is a specialized linear-beam vacuum tube . Klystrons are used as amplifiers at microwave and radio frequencies to produce both low-power reference signals for superheterodyne radar receivers and to produce high-power carrier waves for communications and the driving force for modern...

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Knife-edge effect

Knife-edge effect

In electromagnetic wave propagation, the knife-edge effect or edge diffraction is a redirection by diffraction of a portion of the incident radiation that strikes a well-defined obstacle such as a mountain range or the edge of a building....

L

Laser

Laser

A laser is a device that emits light through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation...

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Launch angle

Launch angle

In fiber optic telecommunications, the launch angle has the following meanings:*The angle, with respect to the normal, at which a light ray emerges from a surface....

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Launch numerical aperture

Launch numerical aperture

In telecommunications, launch numerical aperture is the numerical aperture of an optical system used to couple power into an optical fiber....

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Lead-lag effect

Lead-lag effect

A lead–lag effect, especially in economics, describes the situation where one variable is correlated with the values of another variable at later times....

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Leaky mode

Leaky mode

A leaky mode or tunneling mode in an optical fiber or other waveguide is a mode having an electric field that decays monotonically for a finite distance in the transverse direction but becomes oscillatory everywhere beyond that finite distance...

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Light bulb –
Light-dependent resistor –
Light-emitting diode

Light-emitting diode

A light-emitting diode is a semiconductor light source. LEDs are used as indicator lamps in many devices and are increasingly used for other lighting...

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Lightning

Lightning

Lightning is an atmospheric electrostatic discharge accompanied by thunder, which typically occurs during thunderstorms, and sometimes during volcanic eruptions or dust storms...

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Limiting

Limiting

Limiting: Any process by which a specified characteristic of the output of a device is prevented from exceeding a predetermined value....

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Line code

Line code

In telecommunication, a line code is a code chosen for use within a communications system for baseband transmission purposes...

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Linear feedback shift register

Linear feedback shift register

A linear feedback shift register is a shift register whose input bit is a linear function of its previous state.The most commonly used linear function of single bits is XOR...

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Linear regulator

Linear regulator

In electronics, a linear regulator is a voltage regulator based on an active device operating in its "linear region" or passive devices like Zener diodes operated in their breakdown region...

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Lip synchronization –
List of telephony terminology –
LM741 –
Low noise amplifier –
Loading characteristic

Loading characteristic

Loading characteristic: In multichannel telephone systems, a plot, for the busy hour, of the equivalent mean power and the peak power as a function of the number of voice channels....

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Loading coil

Loading coil

In electronics, a loading coil or load coil is a coil that does not provide coupling to any other circuit, but is inserted in a circuit to increase its inductance. The need was discovered by Oliver Heaviside in studying the disappointing slow speed of the Transatlantic telegraph cable...

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Loading

Loading

In electrical transmission lines, the term loading means the insertion of impedance into a circuit to change the characteristics of the circuit....

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Lobe –
Local battery –
Logic families –
Logic gate

Logic gate

A logic gate is an idealized or physical device implementing a Boolean function, that is, it performs a logical operation on one or more logic inputs and produces a single logic output. Depending on the context, the term may refer to an ideal logic gate, one that has for instance zero rise time and...

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Logic

Logic

In philosophy, Logic is the formal systematic study of the principles of valid inference and correct reasoning. Logic is used in most intellectual activities, but is studied primarily in the disciplines of philosophy, mathematics, semantics, and computer science...

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Log-periodic antenna

Log-periodic antenna

In telecommunication, a log-periodic antenna is a broadband, multi-element, unidirectional, narrow-beam antenna that has impedance and radiation characteristics that are regularly repetitive as a logarithmic function of the excitation frequency...

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Long-haul communications

Long-haul communications

In telecommunication, the term long-haul communications has the following meanings:1. In public switched networks, pertaining to circuits that span large distances, such as the circuits in inter-LATA, interstate, and international communications...

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Longitudinal redundancy check

Longitudinal redundancy check

In telecommunication, a longitudinal redundancy check or horizontal redundancy check is a form of redundancy check that is applied independently to each of a parallel group of bit streams...

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Long-tailed pair –
Long-term stability

Long-term stability

The long-term stability of an oscillator, the degree of uniformity of frequency over time, when the frequency is measured under identical environmental conditions, such as supply voltage, load, and temperature. Long-term frequency changes are caused by changes in the oscillator elements that...

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Loop –
Loop gain

Loop gain

Loop gain is an engineering term used to quantify the gain of a system controlled by feedback loops. As such, the concept of loop gain is useful in a variety of disciplines. Traditionally, most of those have been in the field of electronics, telecommunications, or control systems...

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Loop-back –
Low frequency

Low frequency

Low frequency or low freq or LF refers to radio frequencies in the range of 30 kHz–300 kHz. In Europe, and parts of Northern Africa and of Asia, part of the LF spectrum is used for AM broadcasting as the longwave band. In the western hemisphere, its main use is for aircraft beacon,...

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Low noise amplifier –
Low-performance equipment

Low-performance equipment

In telecommunication, the term low-performance equipment has the following meanings:* Equipment that has imprecise characteristics that do not meet system reliability requirements....

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Lumped element model

Lumped element model

The lumped element model simplifies the description of the behaviour of spatially distributed physical systems into a topology consisting of discrete entities that approximate the behaviour of the distributed system under certain assumptions...

M

Macroelectronics

Macroelectronics

For over half of century, the technology of microelectronics has been advancing by miniaturization, leading to significant increases in computing power and continuous decreases in manufacturing cost...

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Magnet

Magnet

A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials, such as iron, and attracts or repels other magnets.A permanent magnet is an object...

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Magnetic core memory

Magnetic core memory

Magnetic-core memory was the predominant form of random-access computer memory for 20 years . It uses tiny magnetic toroids , the cores, through which wires are threaded to write and read information. Each core represents one bit of information...

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Magnetic field

Magnetic field

A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude ; as such it is a vector field.Technically, a magnetic field is a pseudo vector;...

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Magnetic flux quantum

Magnetic flux quantum

The magnetic flux quantum Φ0 is the quantum of magnetic flux passing through a superconductor. The phenomenon of flux quantization was discovered B. S. Deaver and W. M. Fairbank and, independently, by R. Doll and M. Nabauer, in 1961...

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Magnetic flux

Magnetic flux

Magnetic flux , is a measure of the amount of magnetic B field passing through a given surface . The SI unit of magnetic flux is the weber...

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Magnetic levitation

Magnetic levitation

Magnetic levitation, maglev, or magnetic suspension is a method by which an object is suspended with no support other than magnetic fields...

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Magnetism

Magnetism

Magnetism is a property of materials that respond at an atomic or subatomic level to an applied magnetic field. Ferromagnetism is the strongest and most familiar type of magnetism. It is responsible for the behavior of permanent magnets, which produce their own persistent magnetic fields, as well...

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Magneto-optic effect

Magneto-optic effect

A magneto-optic effect is any one of a number of phenomena in which an electromagnetic wave propagates through a medium that has been altered by the presence of a quasistatic magnetic field...

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Magnetosphere

Magnetosphere

A magnetosphere is formed when a stream of charged particles, such as the solar wind, interacts with and is deflected by the intrinsic magnetic field of a planet or similar body. Earth is surrounded by a magnetosphere, as are the other planets with intrinsic magnetic fields: Mercury, Jupiter,...

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Magnetron –
Main distribution frame

Main distribution frame

In telephony, a main distribution frame is a signal distribution frame for connecting equipment to cables and subscriber carrier equipment . The MDF is a termination point within the local telephone exchange where exchange equipment and terminations of local loops are connected by jumper wires...

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Main lobe

Main lobe

The main lobe, or main beam, of an antenna radiation pattern is the lobe containing the maximum power. This is the lobe that exhibits the greatest field strength....

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Manchester code

Manchester code

In telecommunication and data storage, Manchester code is a line code in which the encoding of each data bit has at least one transition and occupies the same time...

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Maser

Maser

A maser is a device that produces coherent electromagnetic waves through amplification by stimulated emission. Historically, “maser” derives from the original, upper-case acronym MASER, which stands for "Microwave Amplification by Stimulated Emission of Radiation"...

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Mask work –
Master frequency generator

Master frequency generator

A master frequency generator or master electronic oscillator, in frequency-division multiplexing , is a piece of equipment used to provide system end-to-end carrier frequency synchronization and frequency accuracy of tones....

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Maximal-ratio combiner –
Maximum power

Maximum power theorem

In electrical engineering, the maximum power transfer theorem states that, to obtain maximum external power from a source with a finite internal resistance, the resistance of the load must be equal to the resistance of the source as viewed from the output terminals...

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Maximum usable frequency

Maximum usable frequency

Maximum usable frequency describes, in radio transmission, using reflection from the regular ionized layers of the ionosphere, the upper frequency limit that can be used for transmission between two points at a specified time, independent of transmitter power...

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Maxwell coil

Maxwell coil

A Maxwell coil is a device for producing a large volume of almost constant magnetic field.-Description:A constant-field Maxwell coil set consists of three coils oriented on the surface of a virtual sphere...

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Maxwell's demon

Maxwell's demon

In the philosophy of thermal and statistical physics, Maxwell's demon is a thought experiment created by the Scottish physicist James Clerk Maxwell to "show that the Second Law of Thermodynamics has only a statistical certainty." It demonstrates Maxwell's point by hypothetically describing how to...

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Maxwell's equations

Maxwell's equations

Maxwell's equations are a set of partial differential equations that, together with the Lorentz force law, form the foundation of classical electrodynamics, classical optics, and electric circuits. These fields in turn underlie modern electrical and communications technologies.Maxwell's equations...

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m-derived filter

M-derived filter

m-derived filters or m-type filters are a type of electronic filter designed using the image method. They were invented by Otto Zobel in the early 1920s. This filter type was originally intended for use with telephone multiplexing and was an improvement on the existing constant k type filter...

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Mean time between outages –
Mediation function

Mediation function

Mediation function: In telecommunications network management, a function that routes or acts on information passing between network elements and network operations....

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Medium frequency

Medium frequency

Medium frequency refers to radio frequencies in the range of 300 kHz to 3 MHz. Part of this band is the medium wave AM broadcast band. The MF band is also known as the hectometer band or hectometer wave as the wavelengths range from ten down to one hectometers...

 (MF) –
Medium-power talker

Medium-power talker

In telecommunication, a medium-power talker is a hypothetical talker, within a log-normal distribution of talkers, whose volume lies at the medium power of all talkers determining the volume distribution at the point of interest....

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Mediumwave

Mediumwave

Medium wave is the part of the medium frequency radio band used mainly for AM radio broadcasting. For Europe the MW band ranges from 526.5 kHz to 1606.5 kHz...

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Michelson-Morley experiment

Michelson-Morley experiment

The Michelson–Morley experiment was performed in 1887 by Albert Michelson and Edward Morley at what is now Case Western Reserve University in Cleveland, Ohio. Its results are generally considered to be the first strong evidence against the theory of a luminiferous ether and in favor of special...

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Microelectronics

Microelectronics

Microelectronics is a subfield of electronics. As the name suggests, microelectronics relates to the study and manufacture of very small electronic components. Usually, but not always, this means micrometre-scale or smaller,. These devices are made from semiconductors...

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Microphone

Microphone

A microphone is an acoustic-to-electric transducer or sensor that converts sound into an electrical signal. In 1877, Emile Berliner invented the first microphone used as a telephone voice transmitter...

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Microwave auditory effect

Microwave auditory effect

The microwave auditory effect, also known as the microwave hearing effect or the Frey effect, consists of audible clicks induced by pulsed/modulated microwave frequencies. The clicks are generated directly inside the human head without the need of any receiving electronic device...

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Microwave oven

Microwave oven

A microwave oven is a kitchen appliance that heats food by dielectric heating, using microwave radiation to heat polarized molecules within the food...

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Microwave

Microwave

Microwaves, a subset of radio waves, have wavelengths ranging from as long as one meter to as short as one millimeter, or equivalently, with frequencies between 300 MHz and 300 GHz. This broad definition includes both UHF and EHF , and various sources use different boundaries...

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MIL-STD-188

MIL-STD-188

MIL-STD-188 is a series of U.S. military standards relating to telecommunications.-Purpose:Faced with “past technical deficiencies in telecommunications systems and equipment and software…that were traced to basic inadequacies in the application of telecommunication standards and to the lack of a...

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Minimum bend radius –
Mode scrambler

Mode scrambler

In telecommunications, a mode scrambler or mode mixer is a device for inducing mode coupling in an optical fiber, or a device that, itself, exhibits a uniform output intensity profile independent of the input mode volume or modal excitation condition...

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Mode volume –
Modem

Modem

A modem is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data...

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Modular synthesizer

Modular synthesizer

The modular synthesizer is a type of synthesizer consisting of separate specialized modules connected by wires to create a so-called patch. Every output generates a signal – an electric voltage of variable strength...

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Modulation factor –
Modulation rate –
Modulation

Modulation

In electronics and telecommunications, modulation is the process of varying one or more properties of a high-frequency periodic waveform, called the carrier signal, with a modulating signal which typically contains information to be transmitted...

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Molecular electronics

Molecular electronics

Molecular electronics, sometimes called moletronics, involves the study and application of molecular building blocks for the fabrication of electronic components...

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Monostable –
Moore's law

Moore's Law

Moore's law describes a long-term trend in the history of computing hardware: the number of transistors that can be placed inexpensively on an integrated circuit doubles approximately every two years....

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Morse code

Morse code

Morse code is a method of transmitting textual information as a series of on-off tones, lights, or clicks that can be directly understood by a skilled listener or observer without special equipment...

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MOS Technology 6501 –
MOS Technology 6502

MOS Technology 6502

The MOS Technology 6502 is an 8-bit microprocessor that was designed by Chuck Peddle and Bill Mensch for MOS Technology in 1975. When it was introduced, it was the least expensive full-featured microprocessor on the market by a considerable margin, costing less than one-sixth the price of...

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MOS Technology SID

MOS Technology SID

The MOS Technology 6581/8580 SID is the built-in Programmable Sound Generator chip of Commodore's CBM-II, Commodore 64, Commodore 128 and Commodore MAX Machine home computers...

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MOS Technology VIC-II

MOS Technology VIC-II

The VIC-II , specifically known as the MOS Technology 6567/8562/8564 , 6569/8565/8566 , is the microchip tasked with generating Y/C/composite video graphics and DRAM refresh signals in the Commodore 64 and C128 home computers.Succeeding MOS's original VIC , the VIC-II was one of the two chips...

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Mu-law algorithm

Mu-law algorithm

The µ-law algorithm is a companding algorithm, primarily used in the digital telecommunication systems of North America and Japan. Companding algorithms reduce the dynamic range of an audio signal...

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Multicoupler –
Multi-element dipole antenna –
Multimeter

Multimeter

A multimeter or a multitester, also known as a VOM , is an electronic measuring instrument that combines several measurement functions in one unit. A typical multimeter may include features such as the ability to measure voltage, current and resistance...

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Multipath propagation –
Multiple access –
Multiple homing

Multiple homing

In telecommunication, the term multiple homing has the following meanings:1. In telephone systems, the connection of a terminal facility so that it can be served by one or several switching centers. Multiple homing may use a single directory number....

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Multiplex baseband

Multiplex baseband

In telecommunication, the term multiplex baseband has the following meanings:1. In frequency-division multiplexing, the frequency band occupied by the aggregate of the signals in the line interconnecting the multiplexing and radio or line equipment....

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Multiplexer

Multiplexer

In electronics, a multiplexer is a device that selects one of several analog or digital input signals and forwards the selected input into a single line. A multiplexer of 2n inputs has n select lines, which are used to select which input line to send to the output...

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Multiplexing

Multiplexing

The multiplexed signal is transmitted over a communication channel, which may be a physical transmission medium. The multiplexing divides the capacity of the low-level communication channel into several higher-level logical channels, one for each message signal or data stream to be transferred...

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Multiplication ALU –
Multivibrator

Multivibrator

A multivibrator is an electronic circuit used to implement a variety of simple two-state systems such as oscillators, timers and flip-flops. It is characterized by two amplifying devices cross-coupled by resistors or capacitors...

N

N connector

N connector

The N connector is a threaded RF connector used to join coaxial cables. It was one of the first connectors capable of carrying microwave-frequency signals, and was invented in the 1940s by Paul Neill of Bell Labs, after whom the connector is named.-Design:Originally, the connector was designed to...

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Nanotechnology

Nanotechnology

Nanotechnology is the study of manipulating matter on an atomic and molecular scale. Generally, nanotechnology deals with developing materials, devices, or other structures possessing at least one dimension sized from 1 to 100 nanometres...

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Nanowire

Nanowire

A nanowire is a nanostructure, with the diameter of the order of a nanometer . Alternatively, nanowires can be defined as structures that have a thickness or diameter constrained to tens of nanometers or less and an unconstrained length. At these scales, quantum mechanical effects are important —...

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Narrative traffic

Narrative traffic

Narrative traffic is data communications consisting of plain or encrypted messages written in a natural language and transmitted in accordance with standard formats and procedures.Examples of narrative traffic include:...

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Narrowband modem

Narrowband modem

In telecommunication, a narrowband modem is a modem whose modulated output signal has an essential frequency spectrum that is limited to that which can be wholly contained within, and faithfully transmitted through, a voice channel with a nominal 4 kHz bandwidth.Note: High frequency modems...

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Narrowband

Narrowband

In radio, narrowband describes a channel in which the bandwidth of the message does not significantly exceed the channel's coherence bandwidth. It is a common misconception that narrowband refers to a channel which occupies only a "small" amount of space on the radio spectrum.The opposite of...

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National Electrical Code (US)

National Electrical Code (US)

The National Electrical Code , or NFPA 70, is a regionally adoptable standard for the safe installation of electrical wiring and equipment...

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Natural frequency –
Nature versus nurture

Nature versus nurture

The nature versus nurture debate concerns the relative importance of an individual's innate qualities versus personal experiences The nature versus nurture debate concerns the relative importance of an individual's innate qualities ("nature," i.e. nativism, or innatism) versus personal experiences...

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Near-field region –
Negative resistance

Negative resistance

Negative resistance is a property of some electric circuits where an increase in the current entering a port results in a decreased voltage across the same port. This is in contrast to a simple ohmic resistor, which exhibits an increase in voltage under the same conditions. Negative resistors are...

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Negative-acknowledge character

Negative-acknowledge character

* In telecommunications, a negative-acknowledge character is a transmission control character sent by a station as a negative response to the station with which the connection has been set up....

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Net gain

Net gain

In telecommunications, net gain is the overall gain of a transmission circuit.Net gain is measured by applying a test signal at an appropriate power level at the input port of a circuit and measuring the power delivered at the output port...

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Netlist

Netlist

The word netlist can be used in several different contexts, but perhaps the most popular is in the field of electronic design. In this context, a "netlist" describes the connectivity of an electronic design....

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Network administration –
Network architecture

Network architecture

Network architecture is the design of a communications network. It is a framework for the specification of a network's physical components and their functional organization and configuration, its operational principles and procedures, as well as data formats used in its operation.In...

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Network management

Network management

Network management refers to the activities, methods, procedures, and tools that pertain to the operation, administration, maintenance, and provisioning of networked systems....

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Neural network

Neural network

The term neural network was traditionally used to refer to a network or circuit of biological neurons. The modern usage of the term often refers to artificial neural networks, which are composed of artificial neurons or nodes...

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Neutral direct-current telegraph system

Neutral direct-current telegraph system

In telecommunication, a neutral direct-current telegraph system is a telegraph system in which current flows during marking intervals and no current flows during spacing intervals for the transmission of signals over a line, and the direction of current flow is immaterial....

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NI Multisim –
Nickel metal hydride –
Noise figure

Noise figure

Noise figure is a measure of degradation of the signal-to-noise ratio , caused by components in a radio frequency signal chain. The noise figure is defined as the ratio of the output noise power of a device to the portion thereof attributable to thermal noise in the input termination at standard...

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Noise level –
Noise power

Noise power

In telecommunication, the term noise power has the following meanings:# The measured total noise per bandwidth unit at the input or output of a device when the signal is not present.# The power generated by a random electromagnetic process....

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Noise temperature –
Noise weighting

Noise weighting

A noise weighting is a specific amplitude-vs.-frequency characteristic that is designed to allow subjectively valid measurement of noise. It emphasises the parts of the spectrum that are most important....

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Noise-cancelling headphone

Noise-cancelling headphone

Noise-cancelling headphones reduce unwanted ambient sounds by means of active noise control . This involves using one or more microphones placed near the ear, and electronic circuitry which uses the microphone signal to generate an "antinoise" signal...

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Noise-equivalent power

Noise-equivalent power

Noise-equivalent power is a measure of the sensitivity of a photodetector or detector system. It is defined as the signal power that gives a signal-to-noise ratio of one in a one hertz output bandwidth. An output bandwidth of one hertz is equivalent to half a second of integration time. The units...

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Non-return-to-zero

Non-return-to-zero

In telecommunication, a non-return-to-zero line code is a binary code in which 1's are represented by one significant condition and 0's are represented by some other significant condition , with no other neutral or rest condition. The pulses have more energy than a RZ code...

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Normalized frequency –
Norton's theorem

Norton's theorem

Norton's theorem for linear electrical networks, known in Europe as the Mayer–Norton theorem, states that any collection of voltage sources, current sources, and resistors with two terminals is electrically equivalent to an ideal current source, I, in parallel with a single resistor, R...

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NTSC

NTSC

NTSC, named for the National Television System Committee, is the analog television system that is used in most of North America, most of South America , Burma, South Korea, Taiwan, Japan, the Philippines, and some Pacific island nations and territories .Most countries using the NTSC standard, as...

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Nuclear magnetic resonance

Nuclear magnetic resonance

Nuclear magnetic resonance is a physical phenomenon in which magnetic nuclei in a magnetic field absorb and re-emit electromagnetic radiation...

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Null

Null (radio)

In radio electronics, a null is an area or vector in an antenna's radiation pattern where the signal cancels out almost entirely.This can be an advantage, as nulls in the horizontal plane can be used to protect other transmitters from interference. If not carefully planned however, nulls can...

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Numbers station

Numbers station

A numbers station is a shortwave radio station of uncertain origin. In the 1950s, Time magazine reported that the numbers stations first appeared shortly after World War II and were using a format that had been used to send weather data during that war.Numbers stations generally broadcast...

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Numerical aperture

Numerical aperture

In optics, the numerical aperture of an optical system is a dimensionless number that characterizes the range of angles over which the system can accept or emit light. By incorporating index of refraction in its definition, NA has the property that it is constant for a beam as it goes from one...

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Numerically controlled oscillator –
Nyquist interval

O

Off-hook

Off-hook

In telephony, the term off-hook has the following meanings:# The condition that exists when a telephone or other user instrument is in use, i.e., during dialing or communicating. Note: off-hook originally referred to the condition that prevailed when telephones had a separate earpiece , which hung...

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Off-line

Off-line

The terms "online" and "offline" have specific meanings in regard to computer technology and telecommunications. In general, "online" indicates a state of connectivity, while "offline" indicates a disconnected state...

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Ohm –
Ohmmeter

Ohmmeter

An ohmmeter is an electrical instrument that measures electrical resistance, the opposition to an electric current. Micro-ohmmeters make low resistance measurements. Megohmmeters measure large values of resistance...

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Ohm's law

Ohm's law

Ohm's law states that the current through a conductor between two points is directly proportional to the potential difference across the two points...

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Oliver Heaviside

Oliver Heaviside

Oliver Heaviside was a self-taught English electrical engineer, mathematician, and physicist who adapted complex numbers to the study of electrical circuits, invented mathematical techniques to the solution of differential equations , reformulated Maxwell's field equations in terms of electric and...

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Omnidirectional antenna

Omnidirectional antenna

In radio communication, an omnidirectional antenna is an antenna which radiates radio wave power uniformly in all directions in one plane, with the radiated power decreasing with elevation angle above or below the plane, dropping to zero on the antenna's axis. This radiation pattern is often...

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One-way trunk

One-way trunk

In telecommunication, a one-way trunk is a trunk between two switching centers, over which traffic may be originated from one preassigned location only....

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On-hook

On-hook

In telephony, the term on-hook has the following meanings:# The condition that exists when a telephone or other user instrument is not in use, i.e., when idle waiting for a call. Note: on-hook originally referred to the storage of an idle telephone receiver, i.e., separate earpiece, on a switchhook...

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On-line –
Open circuit –
Open spectrum

Open spectrum

Open spectrum is a movement to get the Federal Communications Commission to provide more unlicensed, radio frequency spectrum that is available for use by all...

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Operational amplifier

Operational amplifier

An operational amplifier is a DC-coupled high-gain electronic voltage amplifier with a differential input and, usually, a single-ended output...

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Optical density –
Optical fiber

Optical fiber

An optical fiber is a flexible, transparent fiber made of a pure glass not much wider than a human hair. It functions as a waveguide, or "light pipe", to transmit light between the two ends of the fiber. The field of applied science and engineering concerned with the design and application of...

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Optical path length

Optical path length

In optics, optical path length or optical distance is the product of the geometric length of the path light follows through the system, and the index of refraction of the medium through which it propagates. A difference in optical path length between two paths is often called the optical path...

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Optical spectrum –
Optoelectronic –
Orthogonal frequency division modulation –
Orthomode transducer

Orthomode transducer

An orthomode transducer is a microwave duct component of the class of microwave circulators. It is commonly referred to as an OMT, and commonly referred as a polarisation duplexer. Such device may be part of a VSAT antenna feed Orthomode transducers serve either to combine or to separate two...

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Oscilloscope

Oscilloscope

An oscilloscope is a type of electronic test instrument that allows observation of constantly varying signal voltages, usually as a two-dimensional graph of one or more electrical potential differences using the vertical or 'Y' axis, plotted as a function of time,...

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Out-of-band signaling –
Output

Output

Output is the term denoting either an exit or changes which exit a system and which activate/modify a process. It is an abstract concept, used in the modeling, system design and system exploitation.-In control theory:...

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Outside plant

Outside plant

In telecommunication, the term outside plant has the following meanings:*In civilian telecommunications, outside plant refers to all of the physical cabling and supporting infrastructure , and any associated hardware located between a demarcation point in a switching facility and a demarcation...

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Overflow –
Overhead information

Overhead information

Overhead information is digital information transferred across the functional interface between a user and a telecommunications system, or between functional units within a telecommunications system, for the purpose of directing or controlling the transfer of user information or the detection and...

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Overmodulation

Overmodulation

Overmodulation is the condition that prevails in telecommunication when the instantaneous level of the modulating signal exceeds the value necessary to produce 100% modulation of the carrier. In the sense of this definition, it is almost always considered a fault condition. In layman's terms, the...

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Override

Manual override

A manual override is a mechanism wherein control is taken from an automated system and given to the user. For example, a manual override in photography refers to the ability for the human photographer to turn off the automatic aperture sizing, automatic focusing, or any other automated system on...

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Overshoot (signal)

Overshoot (signal)

In signal processing, control theory, electronics, and mathematics, overshoot is when a signal or function exceeds its target. It arises especially in the step response of bandlimited systems such as low-pass filters...

P

Packet switching

Packet switching

Packet switching is a digital networking communications method that groups all transmitted data – regardless of content, type, or structure – into suitably sized blocks, called packets. Packet switching features delivery of variable-bit-rate data streams over a shared network...

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Packet-switching node

Packet-switching node

Packet-switching node: In a packet-switching network, a node that contains data switches and equipment for controlling, formatting, transmitting, routing, and receiving data packets....

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Paired disparity code

Paired disparity code

In telecommunication, a paired disparity code is a line code in which some or all of the characters are represented by two sets of digits of opposite disparity that are used in sequence so as to minimize the total disparity of a longer sequence of digits....

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PAL

PAL

PAL, short for Phase Alternating Line, is an analogue television colour encoding system used in broadcast television systems in many countries. Other common analogue television systems are NTSC and SECAM. This page primarily discusses the PAL colour encoding system...

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Par meter –
Parabolic antenna

Parabolic antenna

A parabolic antenna is an antenna that uses a parabolic reflector, a curved surface with the cross-sectional shape of a parabola, to direct the radio waves. The most common form is shaped like a dish and is popularly called a dish antenna or parabolic dish...

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Parabolic microphone

Parabolic microphone

A parabolic microphone is a microphone that uses a parabolic reflector to collect and focus sound waves onto a receiver, in much the same way that a parabolic antenna does with radio waves...

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Parallel transmission –
Parasitic element (electrical networks)

Parasitic element (electrical networks)

In electrical networks, a parasitic element is a circuit element that is possessed by an electrical component but which it is not desirable for it to have for its intended purpose. For instance, a resistor is designed to possess resistance, but will also possess unwanted parasitic...

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Parity bit

Parity bit

A parity bit is a bit that is added to ensure that the number of bits with the value one in a set of bits is even or odd. Parity bits are used as the simplest form of error detecting code....

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Passband

Passband

A passband is the range of frequencies or wavelengths that can pass through a filter without being attenuated.A bandpass filtered signal , is known as a bandpass signal, as opposed to a baseband signal....

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Passive radiator

Passive radiator

In a radio antenna, a passive radiator or parasitic element is a conductive element, typically a metal rod, which is not electrically connected to anything else. Multielement antennas such as the Yagi-Uda antenna typically consist of a "driven element" which is connected to the radio receiver...

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Patch bay –
Path loss

Path loss

Path loss is the reduction in power density of an electromagnetic wave as it propagates through space. Path loss is a major component in the analysis and design of the link budget of a telecommunication system....

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Path profile

Path profile

In telecommunication, a path profile is a graphic representation of the physical features of a propagation path in the vertical plane containing both endpoints of the path, showing the surface of the Earth and including trees, buildings, and other features that may obstruct the radio...

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Pauli exclusion principle

Pauli exclusion principle

The Pauli exclusion principle is the quantum mechanical principle that no two identical fermions may occupy the same quantum state simultaneously. A more rigorous statement is that the total wave function for two identical fermions is anti-symmetric with respect to exchange of the particles...

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PBER –
PCB layout guidelines –
Peak envelope power

Peak envelope power

Peak envelope power is the average power supplied to the antenna transmission line by a transmitter during one radio frequency cycle at the crest of the modulation envelope, under normal operating conditions. The United States Federal Communications Commission uses PEP to set maximum power...

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Peltier effect –
Performance measurement period

Performance measurement period

In telecommunication, performance measurement period is the period during which performance parameters are measured.A performance measurement period is determined by required confidence limits and may vary as a function of the observed parameter values. User time is divided into consecutive...

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Periodic antenna –
Periscope antenna

Periscope antenna

In telecommunication, a periscope antenna is an antenna configuration in which the transmitting antenna is oriented to produce a vertical radiation pattern, and a flat or off-axis parabolic reflector, mounted above the transmitting antenna, is used to direct the beam in a horizontal path toward the...

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Permeability

Permeability (electromagnetism)

In electromagnetism, permeability is the measure of the ability of a material to support the formation of a magnetic field within itself. In other words, it is the degree of magnetization that a material obtains in response to an applied magnetic field. Magnetic permeability is typically...

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Permittivity

Permittivity

In electromagnetism, absolute permittivity is the measure of the resistance that is encountered when forming an electric field in a medium. In other words, permittivity is a measure of how an electric field affects, and is affected by, a dielectric medium. The permittivity of a medium describes how...

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Personal Locator Beacon –
Phantom circuit

Phantom circuit

In telecommunication and electrical engineering, a phantom circuit is an electrical circuit derived from suitably arranged wires with one or more conductive paths being a circuit in itself and at the same time acting as one conductor of another circuit....

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Phantom loop –
Phase

Phase (waves)

Phase in waves is the fraction of a wave cycle which has elapsed relative to an arbitrary point.-Formula:The phase of an oscillation or wave refers to a sinusoidal function such as the following:...

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Phase distortion

Phase distortion

In signal processing, phase distortion or phase-frequency distortion is distortion that occurs when a filter's phase response is not linear over the frequency range of interest, that is, the phase shift introduced by a circuit or device is not directly proportional to frequency, or the...

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Phase jitter –
Phase modulation

Phase modulation

Phase modulation is a form of modulation that represents information as variations in the instantaneous phase of a carrier wave.Unlike its more popular counterpart, frequency modulation , PM is not very widely used for radio transmissions...

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Phase noise

Phase noise

Phase noise is the frequency domain representation of rapid, short-term, random fluctuations in the phase of a waveform, caused by time domain instabilities...

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Phase perturbation

Phase perturbation

Phase perturbation is the shifting, from whatever cause, in the phase of an electronic signal. The shifting is often quite rapid, and may appear to be random or cyclic. The phase departure in phase perturbation usually is larger, but less rapid, than in phase jitter.Phase perturbation may be...

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Phased array

Phased array

In wave theory, a phased array is an array of antennas in which the relative phases of the respective signals feeding the antennas are varied in such a way that the effective radiation pattern of the array is reinforced in a desired direction and suppressed in undesired directions.An antenna array...

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Phase-locked loop

Phase-locked loop

A phase-locked loop or phase lock loop is a control system that generates an output signal whose phase is related to the phase of an input "reference" signal. It is an electronic circuit consisting of a variable frequency oscillator and a phase detector...

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Phase-shift keying

Phase-shift keying

Phase-shift keying is a digital modulation scheme that conveys data by changing, or modulating, the phase of a reference signal ....

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Philberth-Transformer –
Photodiode

Photodiode

A photodiode is a type of photodetector capable of converting light into either current or voltage, depending upon the mode of operation.The common, traditional solar cell used to generateelectric solar power is a large area photodiode....

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Photoelectric effect

Photoelectric effect

In the photoelectric effect, electrons are emitted from matter as a consequence of their absorption of energy from electromagnetic radiation of very short wavelength, such as visible or ultraviolet light. Electrons emitted in this manner may be referred to as photoelectrons...

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Photolithography

Photolithography

Photolithography is a process used in microfabrication to selectively remove parts of a thin film or the bulk of a substrate. It uses light to transfer a geometric pattern from a photomask to a light-sensitive chemical "photoresist", or simply "resist," on the substrate...

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Photon

Photon

In physics, a photon is an elementary particle, the quantum of the electromagnetic interaction and the basic unit of light and all other forms of electromagnetic radiation. It is also the force carrier for the electromagnetic force...

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Physical layer

Physical layer

The physical layer or layer 1 is the first and lowest layer in the seven-layer OSI model of computer networking. The implementation of this layer is often termed PHY....

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Pickup –
PID controller

PID controller

A proportional–integral–derivative controller is a generic control loop feedback mechanism widely used in industrial control systems – a PID is the most commonly used feedback controller. A PID controller calculates an "error" value as the difference between a measured process variable and a...

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Piezoelectricity

Piezoelectricity

Piezoelectricity is the charge which accumulates in certain solid materials in response to applied mechanical stress. The word piezoelectricity means electricity resulting from pressure...

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Pin grid array

Pin grid array

A pin grid array, often abbreviated PGA, is a type of integrated circuit packaging. In a PGA, the package is square or roughly square, and the pins are arranged in a regular array on the underside of the package...

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Pirate radio

Pirate radio

Pirate radio is illegal or unregulated radio transmission. The term is most commonly used to describe illegal broadcasting for entertainment or political purposes, but is also sometimes used for illegal two-way radio operation...

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Planar array

Planar array

In telecommunications and radar, a planar array is an antenna in which all of the elements, both active and parasitic, are in one plane. A planar array provides a large aperture and may be used for directional beam control by varying the relative phase of each element...

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Planar array

Planar array

In telecommunications and radar, a planar array is an antenna in which all of the elements, both active and parasitic, are in one plane. A planar array provides a large aperture and may be used for directional beam control by varying the relative phase of each element...

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Planck's constant –
Plesiochronous Digital Hierarchy

Plesiochronous Digital Hierarchy

The Plesiochronous Digital Hierarchy is a technology used in telecommunications networks to transport large quantities of data over digital transport equipment such as fibre optic and microwave radio systems...

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Point-to-point construction

Point-to-point construction

Point-to-point construction refers to the method in which electronics circuits were constructed before the 1950s. Point-to-point construction is still used to construct prototype equipment with few or heavy electronic components....

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Polarential telegraph system

Polarential telegraph system

A polarential telegraph system is a direct-current telegraph system employing polar transmission in one direction and a form of differential duplex transmission in the other....

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Polarization –
Polling

Polling (computer science)

Polling, or polled operation, in computer science, refers to actively sampling the status of an external device by a client program as a synchronous activity. Polling is most often used in terms of input/output , and is also referred to as polled or software driven .Polling is sometimes used...

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Polyphase system

Polyphase system

A polyphase system is a means of distributing alternating current electrical power. Polyphase systems have three or more energized electrical conductors carrying alternating currents with a definite time offset between the voltage waves in each conductor. Polyphase systems are particularly useful...

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Portable people meter

Portable People Meter

The Portable People Meter is a system developed by Arbitron to measure how many people are listening to individual radio stations and television stations, including cable TV. The PPM is worn like a pager, and detects hidden audio tones within a station or network's audio stream, logging each...

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Potential difference –
Potential divider –
Power

Power (physics)

In physics, power is the rate at which energy is transferred, used, or transformed. For example, the rate at which a light bulb transforms electrical energy into heat and light is measured in watts—the more wattage, the more power, or equivalently the more electrical energy is used per unit...

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Power connector

Power connector

Power connector may refer to:* AC power plugs and sockets* Industrial power plug* DC connector* Blade connector, commonly found in cars for quick connection of wiring to electrical components* IEC 60309 , so-called "Commando" plug and socket...

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Power supply

Power supply

A power supply is a device that supplies electrical energy to one or more electric loads. The term is most commonly applied to devices that convert one form of electrical energy to another, though it may also refer to devices that convert another form of energy to electrical energy...

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Preamplifier

Preamplifier

A preamplifier is an electronic amplifier that prepares a small electrical signal for further amplification or processing. A preamplifier is often placed close to the sensor to reduce the effects of noise and interference. It is used to boost the signal strength to drive the cable to the main...

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Preemphasis network

Preemphasis network

In telecommunication, a pre-emphasis network is a network inserted in a system in order to increase the magnitude of one range of frequencies with respect to another....

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Preemphasis

Preemphasis

In processing electronic audio signals, pre-emphasis refers to a system process designed to increase the magnitude of some frequencies with respect to the magnitude of other frequencies in order to improve the overall signal-to-noise ratio by minimizing the adverse effects of such phenomena as...

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Preferred values –
Preventive maintenance

Preventive maintenance

Preventive maintenance has the following meanings:#The care and servicing by personnel for the purpose of maintaining equipment and facilities in satisfactory operating condition by providing for systematic inspection, detection, and correction of incipient failures either before they occur or...

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Primary channel

Primary channel

In telecommunication, the term primary channel has the following meanings:# The channel that is designated as a prime transmission channel and is used as the first choice in restoring priority circuits....

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Primary line constants

Primary line constants

The primary line constants are parameters that describe the characteristics of copper transmission lines in terms of the physical electrical properties of the line. The primary line constants are only relevant to copper lines and are to be contrasted with the secondary line constants, which can...

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Primary time standard

Primary time standard

In telecommunications, a primary time standard is a time standard that does not require calibration against another time standard.Examples of primary time, are caesium standards and hydrogen masers....

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Principal clock

Principal clock

In telecommunications, the principal clock of a set of redundant clocks, is the clock that is selected for normal use. The principal clock may be selected because of a property, e.g. superior accuracy, that makes it a unique member of the set....

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Printed circuit board

Printed circuit board

A printed circuit board, or PCB, is used to mechanically support and electrically connect electronic components using conductive pathways, tracks or signal traces etched from copper sheets laminated onto a non-conductive substrate. It is also referred to as printed wiring board or etched wiring...

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Processor register

Processor register

In computer architecture, a processor register is a small amount of storage available as part of a CPU or other digital processor. Such registers are addressed by mechanisms other than main memory and can be accessed more quickly...

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Product detector

Product detector

A product detector is a type of demodulator used for AM and SSB signals. Rather than converting the envelope of the signal into the decoded waveform like an envelope detector, the product detector takes the product of the modulated signal and a local oscillator, hence the name...

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Programmable logic device

Programmable logic device

A programmable logic device or PLD is an electronic component used to build reconfigurable digital circuits. Unlike a logic gate, which has a fixed function, a PLD has an undefined function at the time of manufacture...

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Propagation delay

Propagation delay

Propagation delay is a technical term that can have a different meaning depending on the context. It can relate to networking, electronics or physics...

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Propagation mode –
Propagation path obstruction

Propagation path obstruction

In telecommunication, a propagation path obstruction is a man-made or natural physical feature that lies near enough to a radio path to cause a measurable effect on path loss, exclusive of reflection effects. An obstruction may lie to the side, above, or below the path. Ridges, bridges, cliffs,...

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Propagation of schema

Propagation of schema

In evolutionary computing such as genetic algorithms and genetic programming, propagation refers to the inheritance of characteristics of one generation by the next. For example, a schema is propagated if individuals in the current generation match it and so do those in the next generation...

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Proration –
Pseudorandom noise

Pseudorandom noise

In cryptography, pseudorandom noise is a signal similar to noise which satisfies one or more of the standard tests for statistical randomness....

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Pseudorandom number sequence –
PSK31

PSK31

PSK31 or "Phase Shift Keying, 31 Baud" is a digital radio modulation mode, used primarily in the amateur radio field to conduct real-time keyboard-to-keyboard informal text chat between amateur radio operators.- History :...

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Pulse amplitude –
Pulse duration

Pulse duration

In signal processing and telecommunication, the term pulse duration has the following meanings:#In a pulse waveform, the interval between the time, during the first transition, that the pulse amplitude reaches a specified fraction of its final amplitude, and the time the pulse amplitude drops,...

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Pulse

Pulse

In medicine, one's pulse represents the tactile arterial palpation of the heartbeat by trained fingertips. The pulse may be palpated in any place that allows an artery to be compressed against a bone, such as at the neck , at the wrist , behind the knee , on the inside of the elbow , and near the...

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Pulse-address multiple access

Pulse-address multiple access

In telecommunications, pulse-address multiple access is a channel access method that enables the ability of a communication satellite to receive signals from several Earth terminals simultaneously and to amplify, translate, and relay the signals back to Earth, based on the addressing of each...

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Pulse-code modulation

Pulse-code modulation

Pulse-code modulation is a method used to digitally represent sampled analog signals. It is the standard form for digital audio in computers and various Blu-ray, Compact Disc and DVD formats, as well as other uses such as digital telephone systems...

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Pulsed inductive thruster

Pulsed inductive thruster

Pulsed inductive thrusters are a form of ion thruster, used in spacecraft propulsion. A PIT uses perpendicular electric and magnetic fields to accelerate a propellant. A nozzle releases a puff of gas which spreads across a flat induction coil of wire about 1 meter across...

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Pulse-width modulation

Pulse-width modulation

Pulse-width modulation , or pulse-duration modulation , is a commonly used technique for controlling power to inertial electrical devices, made practical by modern electronic power switches....

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Push-to-talk operation –
Push-to-type operation

Push-to-type operation

Push-to-type operation: In telegraph or data transmission systems, that method of communication in which the operator at a station must keep a switch operated in order to send messages....

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Pyroelectricity

Pyroelectricity

Pyroelectricity is the ability of certain materials to generate a temporary voltage when they are heated or cooled. The change in temperature modifies the positions of the atoms slightly within the crystal structure, such that the polarization of the material changes. This polarization change...

Q

Q code

Q code

The Q code is a standardized collection of three-letter message encodings, also known as a brevity code, all of which start with the letter "Q", initially developed for commercial radiotelegraph communication, and later adopted by other radio services, especially amateur radio...

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QRP operation

QRP operation

In amateur radio, QRP operation means transmitting at reduced power levels while aiming to maximize one's effective range while doing so. The term QRP derives from the standard Q code used in radio communications, where "QRP" and "QRP?" are used to request, "Reduce power," and ask "Should I reduce...

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Q-switching

Q-switching

Q-switching, sometimes known as giant pulse formation, is a technique by which a laser can be made to produce a pulsed output beam. The technique allows the production of light pulses with extremely high peak power, much higher than would be produced by the same laser if it were operating in a...

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Quadrature amplitude modulation

Quadrature amplitude modulation

Quadrature amplitude modulation is both an analog and a digital modulation scheme. It conveys two analog message signals, or two digital bit streams, by changing the amplitudes of two carrier waves, using the amplitude-shift keying digital modulation scheme or amplitude modulation analog...

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Quadrature –
Quality assurance

Quality Assurance

Quality assurance, or QA for short, is the systematic monitoring and evaluation of the various aspects of a project, service or facility to maximize the probability that minimum standards of quality are being attained by the production process...

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Quality control

Quality control

Quality control, or QC for short, is a process by which entities review the quality of all factors involved in production. This approach places an emphasis on three aspects:...

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Quantum harmonic oscillator

Quantum harmonic oscillator

The quantum harmonic oscillator is the quantum-mechanical analog of the classical harmonic oscillator. Because an arbitrary potential can be approximated as a harmonic potential at the vicinity of a stable equilibrium point, it is one of the most important model systems in quantum mechanics...

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Quartz clock

Quartz clock

A quartz clock is a clock that uses an electronic oscillator that is regulated by a quartz crystal to keep time. This crystal oscillator creates a signal with very precise frequency, so that quartz clocks are at least an order of magnitude more accurate than good mechanical clocks...

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Quasi-analog signal

Quasi-analog signal

In telecommunication, a quasi-analog signal is a digital signal that has been converted to a form suitable for transmission over a specified analog channel....

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Queuing delay

Queuing delay

In telecommunication and computer engineering, the queuing delay is the time a job waits in a queue until it can be executed. It is a key component of network delay....

R

Race hazard –
Radar

Radar

Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...

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Radiation angle

Radiation angle

In fiber optics, the radiation angle is half the vertex angle of the cone of light emitted at the exit face of an optical fiber.The cone boundary is usually defined by the angle at which the far-field irradiance has decreased to a specified fraction of its maximum value or as the cone within...

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Radiation mode –
Radiation pattern

Radiation pattern

In the field of antenna design the term radiation pattern most commonly refers to the directional dependence of the strength of the radio waves from the antenna or other source ....

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Radiation resistance

Radiation resistance

Radiation resistance is that part of an antenna's feedpoint resistance that is caused by the radiation of electromagnetic waves from the antenna. The radiation resistance is determined by the geometry of the antenna, not by the materials of which it is made...

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Radiator

Radiator

Radiators are heat exchangers used to transfer thermal energy from one medium to another for the purpose of cooling and heating. The majority of radiators are constructed to function in automobiles, buildings, and electronics...

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Radio beam –
Radio clock

Radio clock

A radio clock or radio-controlled clock is a clock that is synchronized by a time code bit stream transmitted by a radio transmitter connected to a time standard such as an atomic clock...

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Radio electronics

Radio electronics

*For the magazine, see Radio-ElectronicsRadio electronics is the sub-field of electrical engineering concerning itself with the class of electronic circuits which receive or transmit radio signals....

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Radio frequency induction –
Radio frequency

Radio frequency

Radio frequency is a rate of oscillation in the range of about 3 kHz to 300 GHz, which corresponds to the frequency of radio waves, and the alternating currents which carry radio signals...

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Radio horizon range –
Radio horizon –
Radio propagation

Radio propagation

Radio propagation is the behavior of radio waves when they are transmitted, or propagated from one point on the Earth to another, or into various parts of the atmosphere...

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Radio range –
Radio Row, Manhattan –
Radio station

Radio station

Radio broadcasting is a one-way wireless transmission over radio waves intended to reach a wide audience. Stations can be linked in radio networks to broadcast a common radio format, either in broadcast syndication or simulcast or both...

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Radio

Radio

Radio is the transmission of signals through free space by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space...

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RadioShack

RadioShack

RadioShack Corporation   is an American franchise of electronics retail stores in the United States, as well as parts of Europe, South America and Africa. As of 2008, RadioShack reported net sales and operating revenues of $4.81 billion. The headquarters of RadioShack is located in Downtown...

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Radiotelephone

Radiotelephone

A radiotelephone is a communications system for transmission of speech over radio. Radiotelephone systems are not necessarily interconnected with the public "land line" telephone network. "Radiotelephone" is often used to describe the usage of radio spectrum where it is important to distinguish the...

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Radioteletype

Radioteletype

Radioteletype is a telecommunications system consisting originally of two or more electromechanical teleprinters in different locations, later superseded by personal computers running software to emulate teleprinters, connected by radio rather than a wired link.The term radioteletype is used to...

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Radix-64 –
Railgun

Railgun

A railgun is an entirely electrical gun that accelerates a conductive projectile along a pair of metal rails using the same principles as the homopolar motor. Railguns use two sliding or rolling contacts that permit a large electric current to pass through the projectile. This current interacts...

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Random access memory –
Randomizer

Randomizer

In telecommunication, a randomizer has the following meanings:# An algorithm that converts an input string into a seemingly random output string of the same length , thus avoiding long sequences of bits of the same value; in this context, a randomizer is also referred to as a scrambler.# An analog...

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Ray transfer matrix analysis

Ray transfer matrix analysis

Ray transfer matrix analysis is a type of ray tracing technique used in the design of some optical systems, particularly lasers...

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RC circuit

RC circuit

A resistor–capacitor circuit ', or RC filter or RC network, is an electric circuit composed of resistors and capacitors driven by a voltage or current source...

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RC –
RCA jack –
RCA

RCA

RCA Corporation, founded as the Radio Corporation of America, was an American electronics company in existence from 1919 to 1986. The RCA trademark is currently owned by the French conglomerate Technicolor SA through RCA Trademark Management S.A., a company owned by Technicolor...

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Reactance –
Receive-after-transmit time delay

Receive-after-transmit time delay

In telecommunication, receive-after-transmit time delay is the time interval between the instant of keying off the local transmitter to stop transmitting and the instant the local receiver output has increased to 90% of its steady-state value in response to an rf signal from a distant...

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Received noise power

Received noise power

In telecommunications, the term received noise power has the following meanings:1. The calculated or measured noise power, within the bandwidth being used, at the receive end of a circuit, channel, link, or system....

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Receiver

Receiver (radio)

A radio receiver converts signals from a radio antenna to a usable form. It uses electronic filters to separate a wanted radio frequency signal from all other signals, the electronic amplifier increases the level suitable for further processing, and finally recovers the desired information through...

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Receiver attack-time delay

Receiver attack-time delay

In telecommunication, receiver attack-time delay is the time interval from the instant a step rf signal, at a level equal to the receiver threshold of sensitivity, is applied to the receiver input to the instant the receiver output amplitude reaches 90% of its steady-state value.If a squelch...

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Reconnaissance satellite –
Record medium

Record medium

In telecommunication, the term record medium has the following meanings:# The physical medium on which information is stored in recoverable form. For example, magnetic tape or disk....

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Reference antenna

Reference antenna

A reference antenna is an antenna with known performance. It is normally used to calibrate other systems.Reference antennas are built with particular care taken to make them simple, robust and repeatable. In a common usage scenario a reference antenna would be used as a transfer standard. First...

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Reference circuit

Reference circuit

A reference circuit is a hypothetical electric circuit of specified equivalent length and configuration, and having a defined transmission characteristic or characteristics, used primarily as a reference for measuring the performance of other, i.e., real, circuits or as a guide for planning and...

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Reference clock

Clock signal

In electronics and especially synchronous digital circuits, a clock signal is a particular type of signal that oscillates between a high and a low state and is utilized like a metronome to coordinate actions of circuits...

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Reference noise

Reference noise

In telecommunication, reference noise is the magnitude of circuit noise chosen as a reference for measurement.Many different levels with a number of different weightings are in current use, and care must be taken to ensure that the proper parameters are stated.Specific ones include: dBa, dBa, dBa,...

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Reference surface

Reference surface

In fiber optic technology, a reference surface is that surface of an optical fiber that is used to contact the transverse-alignment elements of a component such as a connector or mechanical splice. For telecommunications-grade fibers, the reference surface is the outer surface of the cladding...

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Reflection coefficient

Reflection coefficient

The reflection coefficient is used in physics and electrical engineering when wave propagation in a medium containing discontinuities is considered. A reflection coefficient describes either the amplitude or the intensity of a reflected wave relative to an incident wave...

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Reflections of signals on conducting lines

Reflections of signals on conducting lines

A signal travelling along an electrical transmission line will be partly, or wholly, reflected back in the opposite direction when the travelling signal encounters a discontinuity in the transmission parameters of the line, or at the far end of the line if the line is not correctly terminated in...

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Reflective array antenna

Reflective array antenna

In telecommunication, a reflective array antenna is an antenna in which multiple driven elements are mounted in front of a surface designed to reflect the radio waves in a desired direction....

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Refractive index contrast

Refractive index contrast

Refractive index contrast, in an optical fiber, is a measure of the relative difference in refractive index of the core and cladding. Refractive index contrast, Δ, is given by Δ = /, where n1 is the maximum refractive index in the core and n2 is the refractive index of the homogeneous cladding....

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Regenerative circuit

Regenerative circuit

The regenerative circuit or "autodyne" allows an electronic signal to be amplified many times by the same vacuum tube or other active component such as a field effect transistor. It consists of an amplifying vacuum tube or transistor with its output connected to its input through a feedback...

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Register transfer level

Register transfer level

In integrated circuit design, register-transfer level is a level of abstraction used in describing the operation of a synchronous digital circuit...

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Registered jack

Registered jack

A registered jack is a standardized physical network interface — both jack construction and wiring pattern — for connecting telecommunications or data equipment to a service provided by a local exchange carrier or long distance carrier. The standard designs for these connectors and their wiring...

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Relational model

Relational model

The relational model for database management is a database model based on first-order predicate logic, first formulated and proposed in 1969 by Edgar F...

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Relative transmission level

Relative transmission level

In telecommunication, relative transmission level is the ratio of the signal power, at a given point in a transmission system, to a reference signal power....

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Relaxation oscillator

Relaxation oscillator

A relaxation oscillator is an oscillator based upon the behavior of a physical system's return to equilibrium after being disturbed. That is, a dynamical system within the oscillator continuously dissipates its internal energy...

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Relay

Relay

A relay is an electrically operated switch. Many relays use an electromagnet to operate a switching mechanism mechanically, but other operating principles are also used. Relays are used where it is necessary to control a circuit by a low-power signal , or where several circuits must be controlled...

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Release time

Release time (telecommunication)

In telecommunication, the term release time has the following meanings:#The time interval between the instant that an enabling signal is discontinued, and the instant at which suppression ceases....

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Remote Operations Service Element protocol

Remote operations service element protocol

The Remote Operations Service Element is the OSI service interface, specified in , that provides remote operation capabilities, allows interaction between entities in a distributed application, and upon receiving a remote operations service request, allows the receiving entity to attempt the...

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Remote sensing

Remote sensing

Remote sensing is the acquisition of information about an object or phenomenon, without making physical contact with the object. In modern usage, the term generally refers to the use of aerial sensor technologies to detect and classify objects on Earth by means of propagated signals Remote sensing...

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Repair and maintenance –
Repeater

Repeater

A repeater is an electronic device that receives asignal and retransmits it at a higher level and/or higher power, or onto the other side of an obstruction, so that the signal can cover longer distances.-Description:...

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Repeating coil

Repeating coil

In telecommunications, a repeating coil is a voice-frequency transformer characterized by a closed magnetic core, a pair of identical balanced primary windings, a pair of identical but not necessarily balanced secondary windings, and low transmission loss at voice frequencies...

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Reproduction speed

Reproduction speed

In telecommunication, the term reproduction speed has the following meanings:# In facsimile systems, the rate at which recorded copy is produced. #In duplicating equipment, the rate at which copies are made...

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Reradiation

Reradiation

In telecommunication, the term reradiation has the following meanings:#Electromagnetic radiation, at the same or different wavelengths, i.e., frequencies, of energy received from an incident wave....

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Resistor color code –
Resistor

Resistor

A linear resistor is a linear, passive two-terminal electrical component that implements electrical resistance as a circuit element.The current through a resistor is in direct proportion to the voltage across the resistor's terminals. Thus, the ratio of the voltage applied across a resistor's...

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Resonance

Resonance

In physics, resonance is the tendency of a system to oscillate at a greater amplitude at some frequencies than at others. These are known as the system's resonant frequencies...

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Response time –
Response

Output

Output is the term denoting either an exit or changes which exit a system and which activate/modify a process. It is an abstract concept, used in the modeling, system design and system exploitation.-In control theory:...

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Responsivity

Responsivity

Responsivity measures the input–output gain of a detector system. For a system that responds linearly to its input, there is a unique responsivity. For nonlinear systems, the responsivity is the local slope ....

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Return loss

Return loss

In telecommunications, return loss or reflection loss is the loss of signal power resulting from the reflection caused at a discontinuity in a transmission line or optical fiber. This discontinuity can be a mismatch with the terminating load or with a device inserted in the line...

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RF connector

RF connector

A coaxial RF connector is an electrical connector designed to work at radio frequencies in the multi-megahertz range.RF connectors are typically used with coaxial cables and are designed to maintain the shielding that the coaxial design offers. Better models also minimize the change in transmission...

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RF modulator

RF modulator

An RF modulator is a device that takes a baseband input signal and outputs a radio frequency-modulated signal....

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RF power margin

RF power margin

In telecommunication, the term RF power margin has the following meanings:#The amount of transmitter power above that which is computed by the link designer as the minimum required to meet specified link performance...

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RF probe

RF probe

An RF probe, sometimes called an RF detector is a simple test device to detect radio frequency oscillation in an electronic circuit. This device will work as a RF rectifier and give a pulsed DC voltage.- References :...

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RF shielding –
RFID –
RGB color space

RGB color space

An RGB color space is any additive color space based on the RGB color model. A particular RGB color space is defined by the three chromaticities of the red, green, and blue additive primaries, and can produce any chromaticity that is the triangle defined by those primary colors...

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Rhombic antenna

Rhombic antenna

A rhombic antenna is a broadband directional antenna co-invented by Edmond Bruce and Harald Friis, mostly commonly used in HF ranges.- Technical Detail :...

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Ring current

Ring current

A ring current is an electric current carried by charged particles trapped in a planet's magnetosphere. It is caused by the longitudinal drift of energetic particles.-Earth's ring current:...

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Ring latency

Ring latency

In a ring network, such as Token Ring, ring latency is the time required for a signal to propagate once around the ring. Ring latency may be measured in seconds or in bits at the data transmission rate. Ring latency includes signal propagation delays in the ring medium, the drop cables, and the...

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Ring modulation

Ring modulation

Ring modulation is a signal-processing effect in electronics, an implementation of amplitude modulation or frequency mixing, performed by multiplying two signals, where one is typically a sine-wave or another simple waveform. It is referred to as "ring" modulation because the analog circuit of...

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Ringback signal –
Ringdown

Ringdown

-Operator signaling:In telephony, ringdown is a method of signaling an operator in which telephone ringing current is sent over the line to operate a lamp or cause the operation of a self-locking relay known as a drop...

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RL circuit

RL circuit

A resistor-inductor circuit ', or RL filter or RL network, is one of the simplest analogue infinite impulse response electronic filters. It consists of a resistor and an inductor, either in series or in parallel, driven by a voltage source.-Introduction:The fundamental passive linear circuit...

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RLC circuit

RLC circuit

An RLC circuit is an electrical circuit consisting of a resistor, an inductor, and a capacitor, connected in series or in parallel. The RLC part of the name is due to those letters being the usual electrical symbols for resistance, inductance and capacitance respectively...

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Robot

Robot

A robot is a mechanical or virtual intelligent agent that can perform tasks automatically or with guidance, typically by remote control. In practice a robot is usually an electro-mechanical machine that is guided by computer and electronic programming. Robots can be autonomous, semi-autonomous or...

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Rogowski coil

Rogowski coil

A Rogowski coil, named after Walter Rogowski, is an electrical device for measuring alternating current or high speed current pulses. It consists of a helical coil of wire with the lead from one end returning through the centre of the coil to the other end, so that both terminals are at the same...

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Root mean square

Root mean square

In mathematics, the root mean square , also known as the quadratic mean, is a statistical measure of the magnitude of a varying quantity. It is especially useful when variates are positive and negative, e.g., sinusoids...

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Routing indicator

Routing indicator

In telecommunication, the term routing indicator has the following meanings:#In a message header, an address, i.e., group of characters, that specifies routing instructions for the transmission of the message to its final destination....

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RS-232

RS-232

In telecommunications, RS-232 is the traditional name for a series of standards for serial binary single-ended data and control signals connecting between a DTE and a DCE . It is commonly used in computer serial ports...

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RX –
Rydberg formula

Rydberg formula

The Rydberg formula is used in atomic physics to describe the wavelengths of spectral lines of many chemical elements. It was formulated by the Swedish physicist Johannes Rydberg, and presented on November 5, 1888.-History:...

S

S/PDIF

S/PDIF

S/PDIF is a digital audio interconnect used in consumer audio equipment over relatively short distances. The signal is transmitted over either a coaxial cable with RCA connectors or a fiber optic cable with TOSLINK connectors. S/PDIF interconnects components in home theaters and other digital high...

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Sacrificial anode –
Sampling frequency –
Scalar field

Scalar field

In mathematics and physics, a scalar field associates a scalar value to every point in a space. The scalar may either be a mathematical number, or a physical quantity. Scalar fields are required to be coordinate-independent, meaning that any two observers using the same units will agree on the...

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Scanner –
Scanning electron microscope

Scanning electron microscope

A scanning electron microscope is a type of electron microscope that images a sample by scanning it with a high-energy beam of electrons in a raster scan pattern...

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SCART

SCART

SCART is a French-originated standard and associated 21-pin connector for connecting audio-visual equipment together...

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Schematic

Schematic

A schematic diagram represents the elements of a system using abstract, graphic symbols rather than realistic pictures. A schematic usually omits all details that are not relevant to the information the schematic is intended to convey, and may add unrealistic elements that aid comprehension...

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Schumann resonance

Schumann resonance

The Schumann resonances are a set of spectrum peaks in the extremely low frequency portion of the Earth's electromagnetic field spectrum...

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Scrambler

Scrambler

In telecommunications, a scrambler is a device that transposes or inverts signals or otherwise encodes a message at the transmitter to make the message unintelligible at a receiver not equipped with an appropriately set descrambling device...

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Screen –
SECAM

SECAM

SECAM, also written SÉCAM , is an analog color television system first used in France....

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Second audio program

Second audio program

Second audio program , also known as secondary audio programming, is an auxiliary audio channel for analog television that can be broadcast or transmitted both over the air and by cable TV.-Usage:...

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Second-order intercept point

Second-order intercept point

The Second Order Intercept Point, also known as the SOI, IP2, or IIP2 , is a measure of linearity that quantifies the second-order distortion generated by nonlinear systems and devices. Examples of frequently used devices that are concerned with this measure are amplifiers and mixers...

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Security management

Security management

Security Management is a broad field of management related to asset management, physical security and human resource safety functions. It entails the identification of an organization's information assets and the development, documentation and implementation of policies, standards, procedures and...

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Self-clocking signal

Self-clocking signal

In telecommunications and electronics, a self-clocking signal is one that can be decoded without the need for a separate clock signal or other source of synchronization...

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Self-synchronizing code

Self-synchronizing code

In telecommunications, a self-synchronizing code is a line code in which the symbol stream formed by a portion of one code word, or by the overlapped portion of any two adjacent code words, is not a valid code word...

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Semiautomatic switching system

Semiautomatic switching system

In telecommunication, the term semiautomatic switching system has the following meanings:#In telephone systems, a switching system in which telephone operators receive call instructions orally from users and complete them by automatic equipment....

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Semiconductor device

Semiconductor device

Semiconductor devices are electronic components that exploit the electronic properties of semiconductor materials, principally silicon, germanium, and gallium arsenide, as well as organic semiconductors. Semiconductor devices have replaced thermionic devices in most applications...

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Semiconductor

Semiconductor

A semiconductor is a material with electrical conductivity due to electron flow intermediate in magnitude between that of a conductor and an insulator. This means a conductivity roughly in the range of 103 to 10−8 siemens per centimeter...

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Sensitivity

Sensitivity (electronics)

The sensitivity of an electronic device, such as a communications system receiver, or detection device, such as a PIN diode, is the minimum magnitude of input signal required to produce a specified output signal having a specified signal-to-noise ratio, or other specified criteria.Sensitivity is...

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Sensor Networks –
Separate channel signaling

Separate channel signaling

Separate channel signaling is a form of signaling in which the whole or a part of one or more channels in a multichannel system is used to provide for supervisory and control signals for the message traffic channels....

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Serial access

Serial access

In telecommunication, the term serial access has the following meanings:#Pertaining to the sequential or consecutive transmission of data into or out of a device, such as a computer, transmission line, or storage device....

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Serial ATA

Serial ATA

Serial ATA is a computer bus interface for connecting host bus adapters to mass storage devices such as hard disk drives and optical drives...

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Serial Peripheral Interface Bus

Serial Peripheral Interface Bus

The Serial Peripheral Interface Bus or SPI bus is a synchronous serial data link standard named by Motorola that operates in full duplex mode. Devices communicate in master/slave mode where the master device initiates the data frame. Multiple slave devices are allowed with individual slave select ...

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Serial transmission –
Series and parallel circuits

Series and parallel circuits

Components of an electrical circuit or electronic circuit can be connected in many different ways. The two simplest of these are called series and parallel and occur very frequently. Components connected in series are connected along a single path, so the same current flows through all of the...

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Shadow loss

Shadow loss

In telecommunication, the term shadow loss has the following meanings:# The attenuation caused to a radio signal by obstructions in the propagation path....

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Shannon limit –
Shannon's theorem –
Short circuit

Short circuit

A short circuit in an electrical circuit that allows a current to travel along an unintended path, often where essentially no electrical impedance is encountered....

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Shortwave

Shortwave

Shortwave radio refers to the upper MF and all of the HF portion of the radio spectrum, between 1,800–30,000 kHz. Shortwave radio received its name because the wavelengths in this band are shorter than 200 m which marked the original upper limit of the medium frequency band first used...

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Shot noise

Shot noise

Shot noise is a type of electronic noise that may be dominant when the finite number of particles that carry energy is sufficiently small so that uncertainties due to the Poisson distribution, which describes the occurrence of independent random events, are of significance...

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Shrinking generator

Shrinking generator

In cryptography, the shrinking generator is a form of pseudorandom number generator intended to be used in a stream cipher. It was published in Crypto 1993 by Don Coppersmith, Hugo Krawczyk, and Yishay Mansour....

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Side lobe

Side lobe

In antenna engineering, side lobes or sidelobes are the lobes of the far field radiation pattern that are not the main lobe....

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Sideband

Sideband

In radio communications, a sideband is a band of frequencies higher than or lower than the carrier frequency, containing power as a result of the modulation process. The sidebands consist of all the Fourier components of the modulated signal except the carrier...

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Sidereal time

Sidereal time

Sidereal time is a time-keeping system astronomers use to keep track of the direction to point their telescopes to view a given star in the night sky...

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Siemens

Siemens (unit)

The siemens is the SI derived unit of electric conductance and electric admittance. Conductance and admittance are the reciprocals of resistance and impedance respectively, hence one siemens is equal to the reciprocal of one ohm, and is sometimes referred to as the mho. In English, the term...

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Signal (information theory) –
Signal compression

Signal compression

In telecommunication, the term signal compression has the following meanings:In analog systems, reduction of the dynamic range of a signal by controlling it as a function of the inverse relationship of its instantaneous value relative to a specified reference level.Signal compression is usually...

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Signal processing gain –
Signal processing

Signal processing

Signal processing is an area of systems engineering, electrical engineering and applied mathematics that deals with operations on or analysis of signals, in either discrete or continuous time...

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Signal reflection

Signal reflection

Signal reflection occurs when a signal is transmitted along a transmission medium, such as a copper cable or an optical fiber, some of the signal power may be reflected back to its origin rather than being carried all the way along the cable to the far end. This happens because imperfections in the...

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Signal transition

Signal transition

Signal transition: In the modulation of a carrier, a change from one significant condition to another.Examples of signal transitions are a change from one electrical current, voltage, or power level to another; a change from one optical power level to another; a phase shift; or a change from one...

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Signal-to-crosstalk ratio

Signal-to-crosstalk ratio

The signal-to-crosstalk ratio at a specified point in a circuit is the ratio of the power of the wanted signal to the power of the unwanted signal from another channel....

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Signal-to-noise ratio

Signal-to-noise ratio

Signal-to-noise ratio is a measure used in science and engineering that compares the level of a desired signal to the level of background noise. It is defined as the ratio of signal power to the noise power. A ratio higher than 1:1 indicates more signal than noise...

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Signature block

Signature block

A signature block is a block of text automatically appended at the bottom of an e-mail message, Usenet article, or forum post. This has the effect of "signing off" the message and in a reply message of indicating that no more response follows...

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Significant condition –
Silicon bandgap temperature sensor

Silicon bandgap temperature sensor

The silicon bandgap temperature sensor is an extremely common form of temperature sensor used in electronic equipment. Its main advantage is that it can be included in a silicon integrated circuit at very low cost...

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Silicon

Silicon

Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...

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Simplex circuit

Simplex circuit

In telecommunication, the term simplex circuit has the following meanings:#A circuit that provides transmission in one direction only.#Deprecated definition: A circuit using ground return and affording communication in either direction, but in only one direction at a time.The above two definitions...

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Simplex signaling

Simplex signaling

Simplex signaling is signaling in which two conductors are used for a single channel, and a center-tapped coil, or its equivalent, is used to split the signaling current equally between the two conductors...

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Sinc filter

Sinc filter

In signal processing, a sinc filter is an idealized filter that removes all frequency components above a given bandwidth, leaves the low frequencies alone, and has linear phase...

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Single frequency networks –
Single phase electric power –
Single-frequency signaling

Single-frequency signaling

Single-frequency signaling is line signaling in which dial pulses or supervisory signals are conveyed by a single voice-frequency tone in each direction...

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Single-polarized antenna –
Single-sideband modulation

Single-sideband modulation

Single-sideband modulation or Single-sideband suppressed-carrier is a refinement of amplitude modulation that more efficiently uses electrical power and bandwidth....

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Skew (antenna)

Skew (antenna)

Skew is a term used in antenna engineering. It is a technique to improve the horizontal radiation pattern of a high power transmitter station.In a high power VHF or UHF station, usually the antenna system is constructed to broadcast to four directions each separated 90° from each other. So the...

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Skin effect

Skin effect

Skin effect is the tendency of an alternating electric current to distribute itself within a conductor with the current density being largest near the surface of the conductor, decreasing at greater depths. In other words, the electric current flows mainly at the "skin" of the conductor, at an...

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Skip zone

Skip zone

A skip zone, also called a silent zone or zone of silence, is a region where a radio transmission can not be received located between regions both nearer and further from the transmitter where reception is possible....

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Skywave

Skywave

Skywave is the propagation of electromagnetic waves bent back to the Earth's surface by the ionosphere. As a result of skywave propagation, a broadcast signal from a distant AM broadcasting station at night, or from a shortwave radio station can sometimes be heard as clearly as local...

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Slant range

Slant range

In radio electronics especially radar terminology, slant range is the line-of-sight distance between two points which are not at the same level relative to a specific datum....

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Slewing

Slew rate

In electronics, the slew rate represents the maximum rate of change of a signal at any point in a circuit.Limitations in slew rate capability can give rise to non linear effects in electronic amplifiers...

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Slew rate

Slew rate

In electronics, the slew rate represents the maximum rate of change of a signal at any point in a circuit.Limitations in slew rate capability can give rise to non linear effects in electronic amplifiers...

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Slot antenna

Slot antenna

A slot antenna consists of a metal surface, usually a flat plate, with a hole or slot cut out. When the plate is driven as an antenna by a driving frequency, the slot radiates electromagnetic waves in similar way to a dipole antenna. The shape and size of the slot, as well as the driving frequency,...

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Slow-scan television

Slow-scan television

Slow-scan television is a picture transmission method used mainly by amateur radio operators, to transmit and receive static pictures via radio in monochrome or color.A technical term for SSTV is narrowband television...

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Software-defined radio

Software-defined radio

A software-defined radio system, or SDR, is a radio communication system where components that have been typically implemented in hardware are instead implemented by means of software on a personal computer or embedded computing devices...

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Solar cell

Solar cell

A solar cell is a solid state electrical device that converts the energy of light directly into electricity by the photovoltaic effect....

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Soldering

Soldering

Soldering is a process in which two or more metal items are joined together by melting and flowing a filler metal into the joint, the filler metal having a lower melting point than the workpiece...

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Solenoid

Solenoid

A solenoid is a coil wound into a tightly packed helix. In physics, the term solenoid refers to a long, thin loop of wire, often wrapped around a metallic core, which produces a magnetic field when an electric current is passed through it. Solenoids are important because they can create...

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Sound card

Sound card

A sound card is an internal computer expansion card that facilitates the input and output of audio signals to and from a computer under control of computer programs. The term sound card is also applied to external audio interfaces that use software to generate sound, as opposed to using hardware...

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Space diversity –
Space tether

Space tether

Space tethers are cables, usually long and very strong, which can be used for propulsion, stabilization, or maintaining the formation of space systems by determining the trajectory of spacecraft and payloads...

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Spark gap

Spark gap

A spark gap consists of an arrangement of two conducting electrodes separated by a gap usually filled with a gas such as air, designed to allow an electric spark to pass between the conductors. When the voltage difference between the conductors exceeds the gap's breakdown voltage, a spark forms,...

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Specific detectivity

Specific detectivity

Specific detectivity, or D*, for a photodetector is a figure of merit used to characterize performance, equal to the reciprocal of noise-equivalent power , normalized per unit area....

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Specification –
Speckle pattern

Speckle pattern

A speckle pattern is a random intensity pattern produced by the mutual interference of a set of wavefronts. This phenomenon has been investigated by scientists since the time of Newton, but speckles have come into prominence since the invention of the laser and have now found a variety of...

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Spectral width

Spectral width

In telecommunications, spectral width is the wavelength interval over which the magnitude of all spectral components is equal to or greater than a specified fraction of the magnitude of the component having the maximum value....

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Spectrum

Spectrum (disambiguation)

A spectrum is a condition or value that is not limited to a specific set of values but can vary infinitely within a continuum.Spectrum may also refer to:-Physical science:* Electromagnetic spectrum...

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Spectrum analyzer

Spectrum analyzer

A spectrum analyzer measures the magnitude of an input signal versus frequency within the full frequency range of the instrument. The primary use is to measure the power of the spectrum of known and unknown signals...

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Speed of light

Speed of light

The speed of light in vacuum, usually denoted by c, is a physical constant important in many areas of physics. Its value is 299,792,458 metres per second, a figure that is exact since the length of the metre is defined from this constant and the international standard for time...

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Speed of service

Speed of service

In telecommunication, the term speed of service has the following meanings:#The time between release of a message by the originator to receipt of the message by the addressee, as perceived by the end user...

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SPICE

SPICE

SPICE is a general-purpose, open source analog electronic circuit simulator.It is a powerful program that is used in integrated circuit and board-level design to check the integrity of circuit designs and to predict circuit behavior.- Introduction :Unlike board-level designs composed of discrete...

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Spill-forward feature

Spill-forward feature

In telecommunication, a spill-forward feature is a service feature, in the operation of an intermediate office, that, acting on incoming trunk service treatment indications, assumes routing control of the call from the originating office. This increases the chances of completion by offering the...

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Spillover –
Spin glass

Spin glass

A spin glass is a magnet with frustrated interactions, augmented by stochastic disorder, where usually ferromagnetic and antiferromagnetic bonds are randomly distributed...

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Spot beam

Spot beam

A spot beam, in telecommunications parlance, is a satellite signal that is specially concentrated in power A spot beam, in telecommunications parlance, is a satellite signal that is specially concentrated in power A spot beam, in telecommunications parlance, is a satellite signal that is specially...

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Spread spectrum

Spread spectrum

Spread-spectrum techniques are methods by which a signal generated in a particular bandwidth is deliberately spread in the frequency domain, resulting in a signal with a wider bandwidth...

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Spurious emission

Spurious emission

A spurious emission is any radio frequency not deliberately created or transmitted, especially in a device which normally does create other frequencies...

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Squelch

Squelch

In telecommunications, squelch is a circuit function that acts to suppress the audio output of a receiver in the absence of a sufficiently strong desired input signal.-Carrier squelch:...

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Standard telegraph level

Standard telegraph level

In telecommunication, standard telegraph level is the power per individual telegraph channel required to yield the standard composite data level....

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Standard test signal

Standard test signal

In telecommunication, a standard test signal is a single-frequency signal with standardized level used for testing the peak power transmission capability and for measuring the total harmonic distortion of circuits or parts of an electric circuit....

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Standard test tone

Standard test tone

In telecommunication, a standard test tone is a single-frequency signal with a standardized level generally used for level alignment of single links and of links in tandem....

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Standing wave ratio

Standing wave ratio

In telecommunications, standing wave ratio is the ratio of the amplitude of a partial standing wave at an antinode to the amplitude at an adjacent node , in an electrical transmission line....

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Standing wave

Standing wave

In physics, a standing wave – also known as a stationary wave – is a wave that remains in a constant position.This phenomenon can occur because the medium is moving in the opposite direction to the wave, or it can arise in a stationary medium as a result of interference between two waves traveling...

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Starpath Supercharger

Starpath Supercharger

The Starpath Supercharger was an add-on module created by Starpath to expand the game capabilities of the Atari 2600 video game console. The device resembled a long game cartridge with a handle on one end. The Supercharger interface multiplied the Atari 2600's RAM 49-fold, from its meager built-in...

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Start signal

Start signal

In telecommunication, the term start signal:# A signal that prepares a device to receive data or to perform a function. Contrast with A-condition....

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Start-stop transmission –
Static electricity

Static electricity

Static electricity refers to the build-up of electric charge on the surface of objects. The static charges remain on an object until they either bleed off to ground or are quickly neutralized by a discharge. Static electricity can be contrasted with current electricity, which can be delivered...

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Steady-state condition

Steady-state condition

In telecommunication, the term steady-state condition has the following meanings:*In a communications circuit, a condition in which some specified characteristic of a condition, such as a value, rate, periodicity, or amplitude, exhibits only negligible change over an arbitrarily long period.*In an...

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Step-index profile

Step-index profile

For an optical fiber, a step-index profile is a refractive index profile characterized by a uniform refractive index within the core and a sharp decrease in refractive index at the core-cladding interface so that the cladding is of a lower refractive index. The step-index profile corresponds to a...

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Stoletov's law

Stoletov's law

Stoletov's law for photoelectric effect establishes the direct proportionality between the intensity of electromagnetic radiation acting on a metallic surface and the photocurrent induced by this radiation. The law was discovered by Aleksandr Stoletov in 1888....

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Stop signal

Stop signal

In telecommunication, the term stop signal has the following meanings:1. In asynchronous serial communication, a signal at the end of a character that prepares the receiving device for the reception of a subsequent character...

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Stopband

Stopband

A stopband is a band of frequencies, between specified limits, through which a circuit, such as a filter or telephone circuit, does not allow signals to pass, or the attenuation is above the required stopband attenuation level...

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Store-and-forward switching center

Store-and-forward switching center

In telecommunication, a store-and-forward switching center is a message switching center in which a message is accepted from the originating user, i.e., sender, when it is offered, held in a physical storage, and forwarded to the destination user, i.e., receiver, in accordance with the priority...

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Stressed environment

Stressed environment

Stressed environment: In radio communications, an environment that is under the influence of extrinsic factors that degrade communications integrity, such as when the benign communications medium is disturbed by natural or man-made events , the received signal is degraded by natural or man-made...

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Strobe light

Strobe light

A strobe light or stroboscopic lamp, commonly called a strobe, is a device used to produce regular flashes of light. It is one of a number of devices that can be used as a stroboscope...

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Stroke speed –
Subcarrier

Subcarrier

A subcarrier is a separate analog or digital signal carried on a main radio transmission, which carries extra information such as voice or data. More technically, it is an already-modulated signal, which is then modulated into another signal of higher frequency and bandwidth...

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Subtractive synthesis

Subtractive synthesis

Subtractive synthesis is a method of sound synthesis in which partials of an audio signal are attenuated by a filter to alter the timbre of the sound...

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Sudden ionospheric disturbance

Sudden Ionospheric Disturbance

A sudden ionospheric disturbance is an abnormally high ionization/plasma density in the D region of the ionosphere caused by a solar flare...

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Supercomputer

Supercomputer

A supercomputer is a computer at the frontline of current processing capacity, particularly speed of calculation.Supercomputers are used for highly calculation-intensive tasks such as problems including quantum physics, weather forecasting, climate research, molecular modeling A supercomputer is a...

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Superconductivity

Superconductivity

Superconductivity is a phenomenon of exactly zero electrical resistance occurring in certain materials below a characteristic temperature. It was discovered by Heike Kamerlingh Onnes on April 8, 1911 in Leiden. Like ferromagnetism and atomic spectral lines, superconductivity is a quantum...

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Superheterodyne receiver

Superheterodyne receiver

In electronics, a superheterodyne receiver uses frequency mixing or heterodyning to convert a received signal to a fixed intermediate frequency, which can be more conveniently processed than the original radio carrier frequency...

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Superparamagnetism

Superparamagnetism

Superparamagnetism is a form of magnetism, which appears in small ferromagnetic or ferrimagnetic nanoparticles. In sufficiently small nanoparticles, magnetization can randomly flip direction under the influence of temperature. The typical time between two flips is called the Néel relaxation time...

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Superposition theorem

Superposition theorem

The superposition theorem for electrical circuits states that the response in any branch of a bilateral linear circuit having more than one independent source equals the algebraic sum of the responses caused by each independent source acting alone, while all other independent sources are replaced...

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Supervisory program

Supervisory program

A supervisory program or supervisor is a computer program, usually part of an operating system, that controls the execution of other routines and regulates work scheduling, input/output operations, error actions, and similar functions and regulates the flow of work in a data processing system.It...

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Suppressed carrier transmission –
Surface wave

Surface wave

In physics, a surface wave is a mechanical wave that propagates along the interface between differing media, usually two fluids with different densities. A surface wave can also be an electromagnetic wave guided by a refractive index gradient...

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Surface-mount technology

Surface-mount technology

Surface mount technology is a method for constructing electronic circuits in which the components are mounted directly onto the surface of printed circuit boards . An electronic device so made is called a surface mount device...

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Surveillance

Surveillance

Surveillance is the monitoring of the behavior, activities, or other changing information, usually of people. It is sometimes done in a surreptitious manner...

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Survivability

Survivability

Survivability is the ability to remain alive or continue to exist. The term has more specific meaning in certain contexts.-Engineering:In engineering, survivability is the quantified ability of a system, subsystem, equipment, process, or procedure to continue to function during and after a natural...

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S-Video

S-Video

Separate Video, more commonly known as S-Video and Y/C, is often referred to by JVC as both an S-VHS connector and as Super Video. It is an analog video transmission scheme, in which video information is encoded on two channels: luma and chroma...

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Switch

Switch

In electronics, a switch is an electrical component that can break an electrical circuit, interrupting the current or diverting it from one conductor to another....

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Switched-mode power supply

Switched-mode power supply

A switched-mode power supply is an electronic power supply that incorporates a switching regulator in order to be highly efficient in the conversion of electrical power...

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Synchronism –
Synchronization

Synchronization

Synchronization is timekeeping which requires the coordination of events to operate a system in unison. The familiar conductor of an orchestra serves to keep the orchestra in time....

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Synchronizing

Synchronizing

In telecommunication, the term synchronizing has the following meanings:# Achieving and maintaining synchronism.# In fax, achieving and maintaining predetermined speed relations between the scanning spot and the recording spot within each scanning line....

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Synchronous network

Synchronous network

In telecommunications, a synchronous network is a network in which clocks are controlled to run, ideally, at identical rates, or at the same mean rate with a fixed relative phase displacement, within a specified limited range....

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Synchronous optical networking

Synchronous optical networking

Synchronous Optical Networking and Synchronous Digital Hierarchy are standardized multiplexing protocols that transfer multiple digital bit streams over optical fiber using lasers or highly coherent light from light-emitting diodes . At low transmission rates data can also be transferred via an...

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Synthesizer

Synthesizer

A synthesizer is an electronic instrument capable of producing sounds by generating electrical signals of different frequencies. These electrical signals are played through a loudspeaker or set of headphones...

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System integrity

System integrity

In telecommunications, the term system integrity has the following meanings:# That condition of a system wherein its mandated operational and technical parameters are within the prescribed limits....

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Systems control

Systems control

Systems control, in a communications system, is the control and implementation of a set of functions that:# prevent or eliminate degradation of any part of the system,# initiate immediate response to demands that are placed on the system,...

T

Table of standard electrode potentials –
Tactical communications system

Tactical communications system

In telecommunication, a tactical communications system is a communications system that is used within, or in direct support of, tactical forces, is designed to meet the requirements of changing tactical situations and varying environmental conditions, provides securable communications, such as...

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Tactical communications

Tactical communications

Tactical communications are communications in which information of any kind, especially orders and decisions, are conveyed from one command, person, or place to another within tactical forces. In modern times, this is usually done by electronic means....

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Tactical data information link--A

Tactical data information link--A

In telecommunication, a tactical data information link—A is a netted link in which one unit acts as a net control station and interrogates each unit by roll call. Once interrogated, that unit transmits its data to the net. This means that each unit receives all the information transmitted. This is...

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Tantalum

Tantalum

Tantalum is a chemical element with the symbol Ta and atomic number 73. Previously known as tantalium, the name comes from Tantalus, a character in Greek mythology. Tantalum is a rare, hard, blue-gray, lustrous transition metal that is highly corrosion resistant. It is part of the refractory...

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Tape relay

Tape relay

A tape relay is a method of retransmitting teletypewriter traffic from one channel to another, in which messages arriving on an incoming channel are recorded in the form of perforated tape, this punched tape then being either fed directly and automatically into an outgoing channel, or manually...

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T-carrier

T-carrier

In telecommunications, T-carrier, sometimes abbreviated as T-CXR, is the generic designator for any of several digitally multiplexed telecommunications carrier systems originally developed by Bell Labs and used in North America, Japan, and South Korea....

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Technical control facility

Technical control facility

In telecommunication, a technical control facility is a physical plant, or a designated and specially configured part thereof, that contains the equipment necessary for ensuring fast, reliable, and secure exchange of information, typically includes distribution frames and associated panels,...

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Telecommunication

Telecommunication

Telecommunication is the transmission of information over significant distances to communicate. In earlier times, telecommunications involved the use of visual signals, such as beacons, smoke signals, semaphore telegraphs, signal flags, and optical heliographs, or audio messages via coded...

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Communications

Telecommunication

Telecommunication is the transmission of information over significant distances to communicate. In earlier times, telecommunications involved the use of visual signals, such as beacons, smoke signals, semaphore telegraphs, signal flags, and optical heliographs, or audio messages via coded...

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Telecommunications service

Telecommunications service

In telecommunication, the term telecommunications service has the following meanings:1. Any service provided by a telecommunication provider....

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Teleconference

Teleconference

A teleconference or teleseminar is the live exchange and mass articulation of information among several persons and machines remote from one another but linked by a telecommunications system...

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Telegrapher's equations –
Telegraphy

Telegraphy

Telegraphy is the long-distance transmission of messages via some form of signalling technology. Telegraphy requires messages to be converted to a code which is known to both sender and receiver...

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Telemetry

Telemetry

Telemetry is a technology that allows measurements to be made at a distance, usually via radio wave transmission and reception of the information. The word is derived from Greek roots: tele = remote, and metron = measure...

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Telephone tapping

Telephone tapping

Telephone tapping is the monitoring of telephone and Internet conversations by a third party, often by covert means. The wire tap received its name because, historically, the monitoring connection was an actual electrical tap on the telephone line...

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Teletext

Teletext

Teletext is a television information retrieval service developed in the United Kingdom in the early 1970s. It offers a range of text-based information, typically including national, international and sporting news, weather and TV schedules...

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Teletraining

Teletraining

Teletraining is training that# usually conveys live instruction via telecommunications facilities,# may be accomplished on a point-to-point basis or on a point-to-multipoint basis, and...

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Television

Television

Television is a telecommunication medium for transmitting and receiving moving images that can be monochrome or colored, with accompanying sound...

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Television reception –
TEMPEST

TEMPEST

TEMPEST is a codename referring to investigations and studies of compromising emission . Compromising emanations are defined as unintentional intelligence-bearing signals which, if intercepted and analyzed, may disclose the information transmitted, received, handled, or otherwise processed by any...

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Tensor

Tensor

Tensors are geometric objects that describe linear relations between vectors, scalars, and other tensors. Elementary examples include the dot product, the cross product, and linear maps. Vectors and scalars themselves are also tensors. A tensor can be represented as a multi-dimensional array of...

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Tesla coil

Tesla coil

A Tesla coil is a type of resonant transformer circuit invented by Nikola Tesla around 1891. It is used to produce high voltage, low current, high frequency alternating current electricity. Tesla coils produce higher current than the other source of high voltage discharges, electrostatic machines...

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Tesla patents –
Test antenna –
Tether propulsion –
Thermal noise –
Thermistor

Thermistor

A thermistor is a type of resistor whose resistance varies significantly with temperature, more so than in standard resistors. The word is a portmanteau of thermal and resistor...

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Thévenin's theorem

Thévenin's theorem

In circuit theory, Thévenin's theorem for linear electrical networks states that any combination of voltage sources, current sources, and resistors with two terminals is electrically equivalent to a single voltage source V and a single series resistor R. For single frequency AC systems the theorem...

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Third-order intercept point

Third-order intercept point

In telecommunications, a third-order intercept point is a measure for weakly nonlinear systems and devices, for example receivers, linear amplifiers and mixers. It is based on the idea that the device nonlinearity can be modeled using a low-order polynomial, derived by means of Taylor series...

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TNC connector

Threaded Neill-Concelman connector

The TNC connector is a threaded version of the BNC connector. The connector has a 50 Ω impedance and operates best in the 0–11 GHz frequency spectrum. It has better performance than the BNC connector at microwave frequencies...

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Three phase –
Time-assignment speech interpolation

Time-assignment speech interpolation

In telecommunication, a time-assignment speech interpolation was an analog technique used on certain long transmission links to increase voice-transmission capacity....

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Time-division multiple access –
Time-division multiplexing

Time-division multiplexing

Time-division multiplexing is a type of digital multiplexing in which two or more bit streams or signals are transferred apparently simultaneously as sub-channels in one communication channel, but are physically taking turns on the channel. The time domain is divided into several recurrent...

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Time-domain reflectometer

Time-domain reflectometer

A time-domain reflectometer is an electronic instrument used to characterize and locate faults in metallic cables . It can also be used to locate discontinuities in a connector, printed circuit board, or any other electrical path...

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Time-out –
Tinfoil hat –
Toll switching trunk

Toll switching trunk

In telecommunication, a toll switching trunk or toll connecting trunk is a trunk connecting one or more end offices to a toll center as the first stage of concentration for intertoll or long distance traffic....

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Total harmonic distortion

Total harmonic distortion

The total harmonic distortion, or THD, of a signal is a measurement of the harmonic distortion present and is defined as the ratio of the sum of the powers of all harmonic components to the power of the fundamental frequency...

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Total internal reflection

Total internal reflection

Total internal reflection is an optical phenomenon that happens when a ray of light strikes a medium boundary at an angle larger than a particular critical angle with respect to the normal to the surface. If the refractive index is lower on the other side of the boundary and the incident angle is...

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Traffic intensity

Traffic intensity

In telecommunication networks, traffic intensity is a measure of the average occupancy of a server or resource during a specified period of time, normally a busy hour.It is measured in traffic units and defined as the ratio of the time during which a facility is cumulatively occupied to the time...

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Traffic shaping

Traffic shaping

Traffic shaping is the control of computer network traffic in order to optimize or guarantee performance, improve latency, and/or increase usable bandwidth for some kinds of packets by delaying other kinds of packets that meet certain criteria...

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Transceiver

Transceiver

A transceiver is a device comprising both a transmitter and a receiver which are combined and share common circuitry or a single housing. When no circuitry is common between transmit and receive functions, the device is a transmitter-receiver. The term originated in the early 1920s...

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Transcoding –
Transducer

Transducer

A transducer is a device that converts one type of energy to another. Energy types include electrical, mechanical, electromagnetic , chemical, acoustic or thermal energy. While the term transducer commonly implies the use of a sensor/detector, any device which converts energy can be considered a...

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Transformer

Transformer

A transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductors—the transformer's coils. A varying current in the first or primary winding creates a varying magnetic flux in the transformer's core and thus a varying magnetic field...

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Transient electromagnetic device –
Transimpedance amplifier –
Transistor radio

Transistor radio

A transistor radio is a small portable radio receiver using transistor-based circuitry. Following their development in 1954 they became the most popular electronic communication device in history, with billions manufactured during the 1960s and 1970s...

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Transistor

Transistor

A transistor is a semiconductor device used to amplify and switch electronic signals and power. It is composed of a semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current...

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Transistor-transistor logic

Transistor-transistor logic

Transistor–transistor logic is a class of digital circuits built from bipolar junction transistors and resistors. It is called transistor–transistor logic because both the logic gating function and the amplifying function are performed by transistors .TTL is notable for being a widespread...

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TTL

Transistor-transistor logic

Transistor–transistor logic is a class of digital circuits built from bipolar junction transistors and resistors. It is called transistor–transistor logic because both the logic gating function and the amplifying function are performed by transistors .TTL is notable for being a widespread...

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Transition metal

Transition metal

The term transition metal has two possible meanings:*The IUPAC definition states that a transition metal is "an element whose atom has an incomplete d sub-shell, or which can give rise to cations with an incomplete d sub-shell." Group 12 elements are not transition metals in this definition.*Some...

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Transmission coefficient

Transmission coefficient

The transmission coefficient is used in physics and electrical engineering when wave propagation in a medium containing discontinuities is considered...

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Transmission level point

Transmission level point

In a telecommunications system, a transmission level point is a test point or interface, i.e. a physical point in an electronic circuit where a test signal may be inserted or measured, and for which the nominal power of the test signal is specified....

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Transmission line

Transmission line

In communications and electronic engineering, a transmission line is a specialized cable designed to carry alternating current of radio frequency, that is, currents with a frequency high enough that its wave nature must be taken into account...

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Transmission medium

Transmission medium

A transmission medium is a material substance that can propagate energy waves...

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Medium

Transmission medium

A transmission medium is a material substance that can propagate energy waves...

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Transmit-after-receive time delay

Transmit-after-receive time delay

In telecommunication, transmit-after-receive time delay is the time interval from removal of RF energy at the local receiver input until the local transmitter is automatically keyed on and the transmitted rf signal amplitude has increased to 90% of its steady-state value...

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Transmitter attack-time delay

Transmitter attack-time delay

In telecommunication, transmitter attack-time delay is the interval from the instant a transmitter is keyed-on to the instant the transmitted radio frequency signal amplitude has increased to a specified level, usually 90% of its key-on steady-state value....

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Transmitter

Transmitter

In electronics and telecommunications a transmitter or radio transmitter is an electronic device which, with the aid of an antenna, produces radio waves. The transmitter itself generates a radio frequency alternating current, which is applied to the antenna. When excited by this alternating...

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Transmitter-studio link –
Transparent latch –
Transponder

Transponder

In telecommunication, the term transponder has the following meanings:...

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Transverse redundancy check

Transverse redundancy check

In telecommunications, a transverse redundancy check or vertical redundancy check is a redundancy check for synchronized parallel bits applied once per bit time, across the bit streams...

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Traveling-wave tube –
TRF

TRF (band)

TRF is a Japanese pop/dance group. Its members are rapper DJ Koo, lead vocalist Yu-ki, and dancers Chiharu, Etsu, and Sam.-History:...

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Triangle wave

Triangle wave

A triangle wave is a non-sinusoidal waveform named for its triangular shape.Like a square wave, the triangle wave contains only odd harmonics...

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Trimline telephone

Trimline telephone

The Western Electric Trimline telephone is a variety of telephone set designed by Donald Genaro of Henry Dreyfuss Associates for the Bell System . It was built by the Bell System's manufacturing arm, Western Electric. The idea behind the Trimline telephone was to create an alternative telephone...

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Troposphere

Troposphere

The troposphere is the lowest portion of Earth's atmosphere. It contains approximately 80% of the atmosphere's mass and 99% of its water vapor and aerosols....

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Tropospheric ducting –
Tropospheric wave

Tropospheric wave

In telecommunication, a tropospheric wave is a radio wave that is propagated by reflection from a place of abrupt change in the dielectric constant, or its gradient, in the troposphere. In some cases, a ground wave may be so altered that new components appear to arise from reflection in regions of...

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TRS connector

TRS connector

A TRS connector is a common family of connector typically used for analog signals including audio. It is cylindrical in shape, typically with three contacts, although sometimes with two or four . It is also called an audio jack, phone jack, phone plug, and jack plug...

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Tuner –
Twisted pair

Twisted pair

Twisted pair cabling is a type of wiring in which two conductors are twisted together for the purposes of canceling out electromagnetic interference from external sources; for instance, electromagnetic radiation from unshielded twisted pair cables, and crosstalk between neighboring pairs...

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TX

Transmission (telecommunications)

Transmission, in telecommunications, is the process of sending, propagating and receiving an analogue or digital information signal over a physical point-to-point or point-to-multipoint transmission medium, either wired, optical fiber or wireless...

U

Ultra high frequency

Ultra high frequency

Ultra-High Frequency designates the ITU Radio frequency range of electromagnetic waves between 300 MHz and 3 GHz , also known as the decimetre band or decimetre wave as the wavelengths range from one to ten decimetres...

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Ultra Wideband –
Ultraviolet

Ultraviolet

Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...

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Unavailability

Unavailability

Unavailability can be defined as the probability that an item will not operate correctly at a given time and under specified conditions. It opposes availability....

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Uncertainty principle

Uncertainty principle

In quantum mechanics, the Heisenberg uncertainty principle states a fundamental limit on the accuracy with which certain pairs of physical properties of a particle, such as position and momentum, can be simultaneously known...

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Uniform linear array –
Unijunction transistor

Unijunction transistor

A unijunction transistor is an electronic semiconductor device that has only one junction. The UJT has three terminals: an emitter and two bases . The base is formed by lightly doped n-type bar of silicon. Two ohmic contacts B1 and B2 are attached at its ends. The emitter is of p-type and it is...

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Unintentional radiator

Unintentional radiator

An unintentional radiator or Incidental radiator is any device which creates radio frequency energy within itself, which is then unintentionally radiated from the device...

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Uplink

Uplink

A telecommunications link is generally one of several types of information transmission paths such as those provided by communication satellites to connect two points on earth.-Uplink:...

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Upright position (electronics) –
User (telecommunications)

User (telecommunications)

In telecommunications, a user is a person, organization, or other entity that employs the services provided by a telecommunication system, or by an information processing system, for transfer of information....

V

VAC –
Vačkář oscillator

Vackár oscillator

A Vackář oscillator is a variation of the split-capacitance oscillator model. It is similar to a Colpitts oscillator or a Clapp oscillator in this respect. It differs in that the output level is relatively stable over frequency, and has a wider bandwidth when compared to a Clapp design.In 1949,...

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Vacuum tube

Vacuum tube

In electronics, a vacuum tube, electron tube , or thermionic valve , reduced to simply "tube" or "valve" in everyday parlance, is a device that relies on the flow of electric current through a vacuum...

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Valence band

Valence band

In solids, the valence band is the highest range of electron energies in which electrons are normally present at absolute zero temperature....

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Variable length buffer

Variable length buffer

In telecommunication, a variable length buffer is a buffer into which data may be entered at one rate and removed at another rate without changing the data sequence....

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Varicap

Varicap

In electronics, a varicap diode, varactor diode, variable capacitance diode, variable reactance diode or tuning diode is a type of diode which has a variable capacitance that is a function of the voltage impressed on its terminals....

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Varistor

Varistor

A varistor is an electronic component with a "diode-like" nonlinear current–voltage characteristic. The name is a portmanteau of variable resistor...

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VDC

Volt

The volt is the SI derived unit for electric potential, electric potential difference, and electromotive force. The volt is named in honor of the Italian physicist Alessandro Volta , who invented the voltaic pile, possibly the first chemical battery.- Definition :A single volt is defined as the...

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Vector field

Vector field

In vector calculus, a vector field is an assignmentof a vector to each point in a subset of Euclidean space. A vector field in the plane for instance can be visualized as an arrow, with a given magnitude and direction, attached to each point in the plane...

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Veroboard –
Very high frequency

Very high frequency

Very high frequency is the radio frequency range from 30 MHz to 300 MHz. Frequencies immediately below VHF are denoted High frequency , and the next higher frequencies are known as Ultra high frequency...

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Very-large-scale integration

Very-large-scale integration

Very-large-scale integration is the process of creating integrated circuits by combining thousands of transistors into a single chip. VLSI began in the 1970s when complex semiconductor and communication technologies were being developed. The microprocessor is a VLSI device.The first semiconductor...

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VHSIC hardware description language

VHSIC Hardware Description Language

VHDL is a hardware description language used in electronic design automation to describe digital and mixed-signal systems such as field-programmable gate arrays and integrated circuits.- History :...

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Video cassette recorder –
Video Game Console

Video game console

A video game console is an interactive entertainment computer or customized computer system that produces a video display signal which can be used with a display device to display a video game...

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Video teleconference –
Video teleconferencing unit

Video teleconferencing unit

A video teleconferencing unit is a piece of electrical equipment that performs videoconferencing functions, such as the coding and decoding of audio and video signals and multiplexing of video, audio, data, and control signals, and that usually does not include Input/Output devices, cryptographic...

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Video

Video

Video is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion.- History :...

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Vintage amateur radio

Vintage amateur radio

Vintage amateur radio is a subset of the amateur radio hobby, considered a form of nostalgia much like antique car collecting, where enthusiasts collect, restore, preserve, build, and operate amateur radio equipment from bygone years, most notably those using vacuum tube technology.Popular modes of...

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Virtual circuit capability –
Virtual circuit

Virtual circuit

In telecommunications and computer networks, a virtual circuit , synonymous with virtual connection and virtual channel, is a connection oriented communication service that is delivered by means of packet mode communication...

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Virtual ground

Virtual ground

Virtual ground is a node of the circuit that is maintained at a steady reference potential, without being connected directly to the reference potential...

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Voice frequency primary patch bay

Voice frequency primary patch bay

In telecommunication, a voice frequency primary patch bay is a patching facility that provides the first appearance of local-user VF circuits in the technical control facility ....

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Voice frequency

Voice frequency

A voice frequency or voice band is one of the frequencies, within part of the audio range, that is used for the transmission of speech.In telephony, the usable voice frequency band ranges from approximately 300 Hz to 3400 Hz...

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Volt

Volt

The volt is the SI derived unit for electric potential, electric potential difference, and electromotive force. The volt is named in honor of the Italian physicist Alessandro Volta , who invented the voltaic pile, possibly the first chemical battery.- Definition :A single volt is defined as the...

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Voltage bias –
Voltage-to-current converter –
Voltmeter

Voltmeter

A voltmeter is an instrument used for measuring electrical potential difference between two points in an electric circuit. Analog voltmeters move a pointer across a scale in proportion to the voltage of the circuit; digital voltmeters give a numerical display of voltage by use of an analog to...

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Vox

W

Wardenclyffe Tower

Wardenclyffe Tower

Wardenclyffe Tower also known as the Tesla Tower, was an early wireless telecommunications tower designed by Nikola Tesla and intended for commercial trans-Atlantic wireless telephony, broadcasting, and to demonstrate the transmission of power without interconnecting wires...

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Warner exemption

Warner exemption

In telecommunication, a Warner exemption is a statutory exemption pertaining to the acquisition of telecommunications systems that meet the exclusionary criteria of the Warner Amendment, Public Law 97-86, 1 December 1981, which is also known as the Brooks Bill....

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Watt

Watt

The watt is a derived unit of power in the International System of Units , named after the Scottish engineer James Watt . The unit, defined as one joule per second, measures the rate of energy conversion.-Definition:...

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Wave impedance

Wave impedance

The wave impedance of an electromagnetic wave is the ratio of the transverse components of the electric and magnetic fields . For a transverse-electric-magnetic plane wave traveling through a homogeneous medium, the wave impedance is everywhere equal to the intrinsic impedance of the medium...

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Wave propagation

Wave propagation

Wave propagation is any of the ways in which waves travel.With respect to the direction of the oscillation relative to the propagation direction, we can distinguish between longitudinal wave and transverse waves....

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Wave

Wave

In physics, a wave is a disturbance that travels through space and time, accompanied by the transfer of energy.Waves travel and the wave motion transfers energy from one point to another, often with no permanent displacement of the particles of the medium—that is, with little or no associated mass...

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Waveform

Waveform

Waveform means the shape and form of a signal such as a wave moving in a physical medium or an abstract representation.In many cases the medium in which the wave is being propagated does not permit a direct visual image of the form. In these cases, the term 'waveform' refers to the shape of a graph...

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Waveguide antenna –
Waveguide

Waveguide

A waveguide is a structure which guides waves, such as electromagnetic waves or sound waves. There are different types of waveguides for each type of wave...

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Wavelength division multiplexing –
Wavelength

Wavelength

In physics, the wavelength of a sinusoidal wave is the spatial period of the wave—the distance over which the wave's shape repeats.It is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings, and is a...

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Wheatstone bridge

Wheatstone bridge

A Wheatstone bridge is an electrical circuit used to measure an unknown electrical resistance by balancing two legs of a bridge circuit, one leg of which includes the unknown component. Its operation is similar to the original potentiometer. It was invented by Samuel Hunter Christie in 1833 and...

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Whip antenna

Whip antenna

A whip antenna is an antenna consisting of a single straight flexible wire or rod, often mounted above some type of conducting surface called a ground plane. The bottom end of the whip is connected to the radio receiver or transmitter. They are designed to be flexible so that they won't break...

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White facsimile transmission

White facsimile transmission

In telecommunication, the term white facsimile transmission has the following meanings:# In an amplitude-modulated facsimile system, transmission in which the maximum transmitted power corresponds to the minimum density, i.e., the white area, of the object.# In a frequency-modulated facsimile...

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Wideband modem

Wideband modem

In telecommunication, the term wideband modem has the following meanings:#A modem whose modulated output signal can have an essential frequency spectrum that is broader than that which can be wholly contained within, and faithfully transmitted through, a voice channel with a nominal 4 kHz...

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Williams tube

Williams tube

The Williams tube or the Williams-Kilburn tube , developed in about 1946 or 1947, was a cathode ray tube used to electronically store binary data....

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Wink pulsing

Wink pulsing

Wink is used both in connection with DC signaling on a trunk, and with indicator lamps on a key telephone.In telephone switching systems, wink pulsing is recurring pulsing in which the off-condition is relatively short compared to the on-condition. In Wink start trunks, the exchange at the...

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Wire wrap

Wire wrap

Wire wrap is a technology used to assemble electronics. It is a method to construct circuit boards without having to make a printed circuit board. Wires can be wrapped by hand or by machine, and can be hand-modified afterwards. It was popular for large-scale manufacturing in the 60s and early 70s,...

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Wire

Wire

A wire is a single, usually cylindrical, flexible strand or rod of metal. Wires are used to bear mechanical loads and to carry electricity and telecommunications signals. Wire is commonly formed by drawing the metal through a hole in a die or draw plate. Standard sizes are determined by various...

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Wireless access point

Wireless access point

In computer networking, a wireless access point is a device that allows wireless devices to connect to a wired network using Wi-Fi, Bluetooth or related standards...

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Wireless community network

Wireless community network

Wireless community networks or wireless community projects are the organizations that attempt to take a grassroots approach to providing a viable alternative to municipal wireless networks for consumers....

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Wireless network

Wireless network

Wireless network refers to any type of computer network that is not connected by cables of any kind. It is a method by which homes, telecommunications networks and enterprise installations avoid the costly process of introducing cables into a building, or as a connection between various equipment...

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Wireless personal area network –
Wireless

Wireless

Wireless telecommunications is the transfer of information between two or more points that are not physically connected. Distances can be short, such as a few meters for television remote control, or as far as thousands or even millions of kilometers for deep-space radio communications...

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X-dimension of recorded spot

X-dimension of recorded spot

X-dimension of recorded spot: In facsimile systems, the effective recorded spot dimension measured in the direction of the recorded line. By "effective recorded spot dimension" is meant the largest center-to-center spacing between recorded spots, which gives minimum peak-to-peak variation of...

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XLR connector

XLR connector

The XLR connector is a style of electrical connector, primarily found on professional audio, video, and stage lighting equipment. The connectors are circular in design and have between 3 and 7 pins...

Z

Zener diode

Zener diode

A Zener diode is a special kind of diode which allows current to flow in the forward direction in the same manner as an ideal diode, but will also permit it to flow in the reverse direction when the voltage is above a certain value known as the breakdown voltage, "Zener knee voltage" or "Zener...

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Zero dBm transmission level point –
Zero insertion force (ZIF) -
Zero-dispersion wavelength

Zero-dispersion wavelength

In a single-mode optical fiber, the zero-dispersion wavelength is the wavelength or wavelengths at which material dispersion and waveguide dispersion cancel one another. In all silica-based optical fibers, minimum material dispersion occurs naturally at a wavelength of approximately 1300nm...

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ZigBee

ZigBee

ZigBee is a specification for a suite of high level communication protocols using small, low-power digital radios based on an IEEE 802 standard for personal area networks. Applications include wireless light switches, electrical meters with in-home-displays, and other consumer and industrial...

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Zig-zag in-line package

Zig-zag in-line package

The zig-zag in-line package or ZIP was a short-lived packaging technology for integrated circuits, particularly dynamic RAM chips. It was intended as a replacement for dual in-line packaging . A ZIP is an integrated circuit encapsulated in a slab of plastic, measuring about 3 mm x 30 mm...

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Zobel network

Zobel network

Zobel networks are a type of filter section based on the image impedance design principle. They are named after Otto Zobel of Bell Labs who published a much referenced paper on image filters in 1923. The distinguishing feature of Zobel networks is that the input impedance is fixed in the design...

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Zone melting

Zone melting

Zone melting is a group of similar methods of purifying crystals, in which a narrow region of a crystal is molten, and this molten zone is moved along the crystal...

Z-transform

Z-transform

In mathematics and signal processing, the Z-transform converts a discrete time-domain signal, which is a sequence of real or complex numbers, into a complex frequency-domain representation....

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