Crosstalk (electronics)
Encyclopedia
In electronics
, crosstalk (XT) is any phenomenon by which a signal transmitted on one circuit or channel of a transmission system
creates an undesired effect in another circuit or channel. Crosstalk is usually caused by undesired capacitive
, inductive
, or conductive coupling
from one circuit
, part of a circuit, or channel
, to another.
, crosstalk can refer to electromagnetic interference
from one unshielded twisted pair
to another twisted pair, normally running in parallel.
Near End Crosstalk (NEXT): Interference between two pairs in a cable measured at the same end of the cable as the transmitter.
Far end crosstalk (FEXT): Interference between two pairs of a cable measured at the other end of the cable from the transmitter.
Alien crosstalk (AXT): Interference caused by other cables routed close to the cable of interest.
or telephony
, crosstalk is often distinguishable as pieces of speech or signaling tones leaking from other people's connections. If the connection is analog, twisted pair
cabling can often be used to reduce the effects of crosstalk. Alternatively, the signals can be converted to digital form, which is much less susceptible to crosstalk.
In wireless communication, crosstalk is often denoted co-channel interference
, and is related to adjacent-channel interference
.
In integrated circuit design
, crosstalk normally refers to a signal affecting another nearby signal. Usually the coupling is capacitive, and to the nearest neighbor, but other forms of coupling and effects on signal further away are sometimes important, especially in analog designs. See signal integrity
for tools used to measure and prevent this problem, and substrate coupling
for a discussion of crosstalk conveyed through the integrated circuit
substrate. There are a wide variety of possible fixes, with increased spacing, wire re-ordering, and shielding being the most common.
In a music recording
setting, the term "crosstalk" can refer to the leakage or "bleeding"
of sound from one instrument into a microphone placed in front of another musical instrument or singer. A common example is the leakage of the high-pitched, heavily-amplified sound of the lead guitar into the microphones for other instruments. Note that this is nearly always an acoustic effect, not electrical.
In stereo
audio reproduction crosstalk can refer to signal leaking across from one program channel to another. This is an electrical effect and can be quantified with a crosstalk measurement
.
In full-field optical coherence tomography
, "crosstalk" refers to the phenomenon that due to highly scattering objects, multiple scattered photons reach the image plane and generate coherent signal after traveling a pathlength that matchs that of the sample depth within a coherence length.
In Stereoscopic 3D Displays
, "crosstalk" refers to the incomplete isolation of the left and right image channels so that one leaks or bleeds into the other - like a double exposure. In this area, crosstalk and ghosting are often used interchangeably, however crosstalk is a physical entity and can be objectively measured, whereas ghosting is a subjective term and refers to the perception of crosstalk.
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...
, crosstalk (XT) is any phenomenon by which a signal transmitted on one circuit or channel of a transmission system
Transmission system
In telecommunications a transmission system is a system that transmits a signal from one place to another. The signal can be an electrical, optical or radio signal....
creates an undesired effect in another circuit or channel. Crosstalk is usually caused by undesired capacitive
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...
, inductive
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...
, or 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...
from one 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...
, part of a circuit, or 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...
, to another.
Crosstalk in cabling
In structured cablingStructured cabling
Structured cabling is building or campus telecommunications cabling infrastructure that consists of a number of standardized smaller elements called subsystems.Structured cabling falls into six subsystems:...
, crosstalk can refer to electromagnetic interference
Electromagnetic interference
Electromagnetic interference is disturbance that affects an electrical circuit due to either electromagnetic induction or electromagnetic radiation emitted from an external source. The disturbance may interrupt, obstruct, or otherwise degrade or limit the effective performance of the circuit...
from one unshielded 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...
to another twisted pair, normally running in parallel.
Near End Crosstalk (NEXT): Interference between two pairs in a cable measured at the same end of the cable as the transmitter.
Far end crosstalk (FEXT): Interference between two pairs of a cable measured at the other end of the cable from the transmitter.
Alien crosstalk (AXT): Interference caused by other cables routed close to the cable of interest.
Other examples
In telecommunicationTelecommunication
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...
or telephony
Telephony
In telecommunications, telephony encompasses the general use of equipment to provide communication over distances, specifically by connecting telephones to each other....
, crosstalk is often distinguishable as pieces of speech or signaling tones leaking from other people's connections. If the connection is analog, 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...
cabling can often be used to reduce the effects of crosstalk. Alternatively, the signals can be converted to digital form, which is much less susceptible to crosstalk.
In wireless communication, crosstalk is often denoted 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....
, and is related to 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...
.
In integrated circuit design
Integrated circuit design
Integrated circuit design, or IC design, is a subset of electrical engineering and computer engineering, encompassing the particular logic and circuit design techniques required to design integrated circuits, or ICs...
, crosstalk normally refers to a signal affecting another nearby signal. Usually the coupling is capacitive, and to the nearest neighbor, but other forms of coupling and effects on signal further away are sometimes important, especially in analog designs. See signal integrity
Signal integrity
Signal integrity or SI is a set of measures of the quality of an electrical signal. In digital electronics, a stream of binary values is represented by a voltage waveform. However, digital signals are fundamentally analog in nature, and all signals are subject to effects such as noise,...
for tools used to measure and prevent this problem, and substrate coupling
Substrate coupling
In an integrated circuit, a signal can couple from one node to another via the substrate. This phenomenon is referred to as substrate coupling or substrate noise coupling....
for a discussion of crosstalk conveyed through the 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...
substrate. There are a wide variety of possible fixes, with increased spacing, wire re-ordering, and shielding being the most common.
In a music recording
Sound recording and reproduction
Sound recording and reproduction is an electrical or mechanical inscription and re-creation of sound waves, such as spoken voice, singing, instrumental music, or sound effects. The two main classes of sound recording technology are analog recording and digital recording...
setting, the term "crosstalk" can refer to the leakage or "bleeding"
Spill (audio)
Spill is the occurrence in sound recording and live sound mixing whereby sound is picked up by a microphone from a source other than that which is intended. Spill is usually seen as a problem, and various steps are taken to avoid it or reduce it...
of sound from one instrument into a microphone placed in front of another musical instrument or singer. A common example is the leakage of the high-pitched, heavily-amplified sound of the lead guitar into the microphones for other instruments. Note that this is nearly always an acoustic effect, not electrical.
In stereo
STEREO
STEREO is a solar observation mission. Two nearly identical spacecraft were launched into orbits that cause them to respectively pull farther ahead of and fall gradually behind the Earth...
audio reproduction crosstalk can refer to signal leaking across from one program channel to another. This is an electrical effect and can be quantified with a crosstalk measurement
Crosstalk measurement
Crosstalk measurement is made on audio systems to determine the amount of signal leaking across from one channel to another.Interchannel crosstalk applies between the two channels of a stereo system, and is usually not very important on modern systems, though it was hard to keep below the desired...
.
In full-field optical coherence tomography
Tomography
Tomography refers to imaging by sections or sectioning, through the use of any kind of penetrating wave. A device used in tomography is called a tomograph, while the image produced is a tomogram. The method is used in radiology, archaeology, biology, geophysics, oceanography, materials science,...
, "crosstalk" refers to the phenomenon that due to highly scattering objects, multiple scattered photons reach the image plane and generate coherent signal after traveling a pathlength that matchs that of the sample depth within a coherence length.
In Stereoscopic 3D Displays
3D display
A 3D display is any display device capable of conveying a stereoscopic perception of 3-D depth to the viewer. The basic requirement is to present offset images that are displayed separately to the left and right eye. Both of these 2-D offset images are then combined in the brain to give the...
, "crosstalk" refers to the incomplete isolation of the left and right image channels so that one leaks or bleeds into the other - like a double exposure. In this area, crosstalk and ghosting are often used interchangeably, however crosstalk is a physical entity and can be objectively measured, whereas ghosting is a subjective term and refers to the perception of crosstalk.
See also
- Audio system measurementsAudio system measurementsAudio 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...
- Co-channel interferenceCo-channel interferenceCo-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....
(CCI) - Signal integritySignal integritySignal integrity or SI is a set of measures of the quality of an electrical signal. In digital electronics, a stream of binary values is represented by a voltage waveform. However, digital signals are fundamentally analog in nature, and all signals are subject to effects such as noise,...
- Substrate couplingSubstrate couplingIn an integrated circuit, a signal can couple from one node to another via the substrate. This phenomenon is referred to as substrate coupling or substrate noise coupling....
- Signal-to-interference ratioSignal-to-interference ratioThe signal-to-interference ratio , also known as the carrier-to-interference ratio , is the quotient between the average received modulated carrier power S or C and the average received co-channel interference power I, i.e...
(SIR or S/I), also known as carrier-to-interference ratio (CIR or C/I) - Unger modelUnger modelThe Unger Model is an empirical standard model for near end crosstalk power spectra as experienced by communication systems over unshielded twisted pair .Twisted pair cables are usually grouped together in a binder where they experience crosstalk...
- Attenuation-to-crosstalk ratio
- MIL-STD-188MIL-STD-188MIL-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...
- Federal Standard 1037CFederal Standard 1037CFederal 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....