Electric beacon - AbsoluteAstronomy.com

Electric beacons are a kind of beacon

Beacon

A beacon is an intentionally conspicuous device designed to attract attention to a specific location.Beacons can also be combined with semaphoric or other indicators to provide important information, such as the status of an airport, by the colour and rotational pattern of its airport beacon, or of...

used with direction finding equipment to find ones relative bearing

Bearing (navigation)

In marine navigation, a bearing is the direction one object is from another object, usually, the direction of an object from one's own vessel. In aircraft navigation, a bearing is the actual compass direction of the forward course of the aircraft...

to a known location

Location (geography)

The terms location and place in geography are used to identify a point or an area on the Earth's surface or elsewhere. The term 'location' generally implies a higher degree of can certainty than "place" which often has an ambiguous boundary relying more on human/social attributes of place identity...

(the beacon

Beacon

).

The term electric beacon includes radio, 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...

and sonar

Sonar

Sonar is a technique that uses sound propagation to navigate, communicate with or detect other vessels...

beacons.

Radio beacons

A radio beacon is a 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...

at a known location, which transmits a continuous or periodic radio signal with limited information content (for example its identification or location), on a specified 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...

. Occasionally the beacon function is combined with some other transmission, like 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...

data or meteorological information.

Radio beacons have many applications, including air and sea navigation, propagation research, robotic mapping

Robotic mapping

Robotic mapping is related to cartography. The goal for an autonomous robot to be able to construct a map or floor plan and to localize itself in it...

, radio frequency identification (radio-frequency identification, RFID) and indoor guidance as with real time locating systems (RTLS) like Syledis

Syledis

Syledis was a terrestrial radio navigation and locating system. The system operated in the UHF segment of 420-450 MHz...

Radio navigation beacons

A most basic aviation radio navigational aid is the NDB

Non-directional beacon

A non-directional beacon is a radio transmitter at a known location, used as an aviation or marine navigational aid. As the name implies, the signal transmitted does not include inherent directional information, in contrast to other navigational aids such as low frequency radio range, VHF...

or Non-directional Beacon. These are simple low frequency and medium frequency transmitters and they are used to locate airways intersections, airports and to conduct instrument approaches, with the use of a radio direction finder located on the aircraft. The aviation NDBs, especially the ones marking airways intersections, are gradually decommissioned, as they are replaced with other navigational aids based on newer technologies. Due to relatively low purchase, maintenance and calibration cost, they are still used to mark locations of smaller aerodromes and important helicopter landing sites.

There are also marine beacons, based on the same technology and installed at coastal areas, for use by ships at sea. Most of them, especially in the western world, are no longer in service, while some have been converted to telemetry

Telemetry

transmitters for differential GPS

Differential GPS

Differential Global Positioning System is an enhancement to Global Positioning System that provides improved location accuracy, from the 15-meter nominal GPS accuracy to about 10 cm in case of the best implementations....

. Chains of radio navigation beacons for marine use are still active around the Russian and Ukrainian coastline.

In addition to dedicated radio beacons, any AM, VHF, or UHF 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...

at a known location can also be used as a beacon with direction finding

Direction finding

Direction finding refers to the establishment of the direction from which a received signal was transmitted. This can refer to radio or other forms of wireless communication...

equipment.

ILS marker beacons

A marker beacon

Marker beacon

A marker beacon is a particular type of VHF radio beacon used in aviation, usually in conjunction with an instrument landing system , to give pilots a means to determine position along an established route to a destination such as a runway...

is a specialized beacon used in aviation in conjunction with an instrument landing system

Instrument Landing System

An instrument landing system is a ground-based instrument approach system that provides precision guidance to an aircraft approaching and landing on a runway, using a combination of radio signals and, in many cases, high-intensity lighting arrays to enable a safe landing during instrument...

(ILS), to give pilots a means to determine distance to the runway. Marker beacons transmit on the dedicated frequency of 75 MHz. This type of beacon is slowly being phased-out and most new ILS installations have no marker beacons.

Radio propagation beacons

A radio propagation beacon

Radio propagation beacon

A radio propagation beacon is a radio beacon, whose purpose is the investigation of the propagation of radio signals. Most radio propagation beacons use amateur radio frequencies. They can be found on HF, VHF, UHF, and microwave frequencies...

is specifically used to study the propagation of radio signals. Nearly all of them are part of the 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...

service.

Single letter HF beacons

A group of radio beacons with single-letter identifiers ("C", "D", "M", "S", "P", etc.) transmitting in morse code have been regularly reported on various HF

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...

frequencies. There is no official information available about these transmitters and they are not registered with the ITU

Itu

Itu is an old and historic municipality in the state of São Paulo in Brazil. The population in 2009 was 157,384 and the area is 641.68 km². The elevation is 583 m. This place name comes from the Tupi language, meaning big waterfall. Itu is linked with the highway numbered the SP-75 and are flowed...

. Some investigators suggest that some of these beacons (the so called "cluster beacons") are actually radio propagation beacon

Radio propagation beacon

s for naval use.

Space and satellite radio beacons

Beacons are also used in both geostationary and inclined orbit satellites. Any satellite will emit one or more beacons (normally on a fixed frequency) whose purpose is twofold; as well as containing modulated station keeping information (telemetry), the beacon is also used to locate the satellite (determine its azimuth and elevation) in the sky.

A beacon was left on the moon by the last Apollo mission

Apollo 17

Apollo 17 was the eleventh and final manned mission in the American Apollo space program. Launched at 12:33 a.m. EST on December 7, 1972, with a three-member crew consisting of Commander Eugene Cernan, Command Module Pilot Ronald Evans, and Lunar Module Pilot Harrison Schmitt, Apollo 17 remains the...

, transmitting FSK telemetry on 2276.0 MHz

Driftnet buoy radio beacons

Driftnet radio buoys are extensively used by fishing boats operating in open seas and oceans. They are useful for collecting long fishing lines or fishing nets, with the assistance of a radio direction finder

Radio direction finder

A radio direction finder is a device for finding the direction to a radio source. Due to low frequency propagation characteristic to travel very long distances and "over the horizon", it makes a particularly good navigation system for ships, small boats, and aircraft that might be some distance...

. According to product information released by manufacturer Kato Electronics Co, Ltd., these buoys transmit on 1600–2850 kHz with a power of 4-15 W.

Some types of driftnet buoys, called "SelCall buoys", answer only when they are called by their own ships. Using this technique the buoy prevents nets and fishing gears from being carried away by other ships, while the battery power consumption remains low.

Distress radiobeacons

Distress radiobeacons, also collectively known as distress beacons, emergency beacons, or simply, beacons, are those tracking transmitter

Tracking transmitter

A Tracking transmitter broadcasts a radio signal which can be detected by a directional antenna By rotating the antenna one can determine the direction the signal lies in and of course whatever it may be attached to...

s that operate as part of the international Cospas-Sarsat

Cospas-Sarsat

Cospas-Sarsat is an international satellite-based search and rescue distress alert detection and information distribution system, established by Canada, France, the United States, and the former Soviet Union in 1979. It is best known as the system that detects and locates emergency beacons...

Search and Rescue

Search and rescue

Search and rescue is the search for and provision of aid to people who are in distress or imminent danger.The general field of search and rescue includes many specialty sub-fields, mostly based upon terrain considerations...

satellite

Satellite

In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavour. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon....

system. When activated, these beacons send out a distress signal

Distress signal

A distress signal is an internationally recognized means for obtaining help. Distress signals take the form of or are commonly made by using radio signals, displaying a visually detected item or illumination, or making an audible sound, from a distance....

that, when detected by non-geostationary satellites, can be located by triangulation

Triangulation

In trigonometry and geometry, triangulation is the process of determining the location of a point by measuring angles to it from known points at either end of a fixed baseline, rather than measuring distances to the point directly...

. In the case of 406 MHz beacons which transmit digital signals, the beacons can be uniquely identified almost instantly (via GEOSAR), and furthermore, a GPS position can be encoded

Encoder

An encoder is a device, circuit, transducer, software program, algorithm or person that converts information from one format or code to another, for the purposes of standardization, speed, secrecy, security, or saving space by shrinking size.-Media:...

into the signal (thus providing both instantaneous identification & position.) Distress signals from the beacons are homed by Search and Rescue (SAR)

Search and rescue

aircraft and ground search parties who can in turn come to the aid of the concerned boat

Boat

A boat is a watercraft of any size designed to float or plane, to provide passage across water. Usually this water will be inland or in protected coastal areas. However, boats such as the whaleboat were designed to be operated from a ship in an offshore environment. In naval terms, a boat is a...

, aircraft

Aircraft

An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...

, and/or persons.

There are three kinds of distress radiobeacons:

EPIRBs (Emergency Position Indicating Radio Beacons) signal maritime distress,
ELTs (Emergency Locator Transmitters) signal aircraft distress
PLBs (Personal Locator Beacons) are for personal use and are intended to indicate a person in distress who is away from normal emergency response capabilities (i.e. 911)

The basic purpose of distress radiobeacons is to get people rescued within the so-called "golden day" http://www1.va.gov/emshg/apps/kml/docs/CERT_Manual.pdf (the first 24 hours following a traumatic event) when the majority of survivors can still be saved.

IEEE 802.11 Wi-Fi beacons

In the field of Wi-Fi

Wi-Fi

Wi-Fi or Wifi, is a mechanism for wirelessly connecting electronic devices. A device enabled with Wi-Fi, such as a personal computer, video game console, smartphone, or digital audio player, can connect to the Internet via a wireless network access point. An access point has a range of about 20...

(wireless local area networks using the IEEE 802.11b and 802.11g specification), the term beacon signifies a specific data transmission from the 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...

(AP), which carries the SSID, the channel number and security protocols such as WEP

WEP

WEP may stand for:* Wired Equivalent Privacy, a deprecated wireless network security standard. Sometimes erroneously called "Wireless Encryption Protocol".* War emergency power, for fighter aircraft...

(Wired Equivalent Privacy) or WPA

Wi-Fi Protected Access

Wi-Fi Protected Access and Wi-Fi Protected Access II are two security protocols and security certification programs developed by the Wi-Fi Alliance to secure wireless computer networks...

(Wi-Fi Protected Access). This transmission does not contain the link layer address of another Wi-Fi device, therefore it can be received by any LAN client.

AX.25 packet radio beacons

Stations participating in packet radio networks based on the AX.25

AX.25

AX.25 is a data link layer protocol derived from the X.25 protocol suite and designed for use by amateur radio operators. It is used extensively on amateur packet radio networks....

link layer protocol also use beacon transmissions to identify themselves and broadcast brief information about operational status. The beacon transmissions use special UI or Unnumbered Information frames, which are not part of a connection and can be displayed by any station. Beacons in traditional AX.25 amateur packet radio networks contain free format information text, readable by human operators.

This mode of AX.25 operation, using a formal machine-readable beacon text specification developed by Bob Bruninga, WB4APR, became the basis of the APRS

Automatic Position Reporting System

Automatic Packet Reporting System is an amateur radio-based system for real time tactical digital communications of information of immediate value in the local area. In addition, all such data is ingested into the APRS Internet system and distributed globally for ubiquitous and immediate access...

networks.

Infrared beacon

An infrared beacon (IR beacon) transmits a modulated light beam in the infrared spectrum, which can be identified easily and positively. A line of sight clear of obstacles between the transmitter and the receiver is essential. IR beacons have a number of applications in robotics

Robotics

Robotics is the branch of technology that deals with the design, construction, operation, structural disposition, manufacture and application of robots...

and in Combat Identification (CID).

Infrared beacons are the key infrastructure for the Universal Traffic Management System (UTMS) in Japan. They perform two-way communication with travelling vehicles based on highly directional infrared communication technology and have a vehicle detecting capability to provide more accurate traffic information.

A contemporary military use of an Infrared beacon is reported in Operation Acid Gambit

Operation Acid Gambit

Operation Acid Gambit was a plan to retrieve Kurt Muse, an American civilian living in Panama and widely reported to be a CIA operative from the Carcel Modelo, a notorious prison in Panama City...