Radio beacon: Difference between revisions

From Wikipedia, the free encyclopedia
Browse history interactively
← Previous editNext edit →
Content deleted Content added
VisualWikitext
→‎Further reading: Added Andrew Talbot's article on 5 MHz beacons
Line 19: Line 19:


===Radio propagation beacons===
===Radio propagation beacons===
[[Image:DRA5.jpg|thumb|QSL card from DRA5 radio propagation beacon]]

These are mostly [[amateur radio]] beacons that are used to study the [[radio propagation|propagation]] of radio signals. They can be found on HF, VHF, UHF and microwave frequencies. The microwave beacons are also used as signal sources to test antennas and receivers.
These are mostly [[amateur radio]] beacons that are used to study the [[radio propagation|propagation]] of radio signals. They can be found on HF, VHF, UHF and microwave frequencies. The microwave beacons are also used as signal sources to test antennas and receivers.


Revision as of 18:46, 19 February 2008

Telegraph Signal Tower at Cobb's Hill, near New Market, Virginia, 1864.

Electric beacons are a kind of beacon used with direction finding equipment to find ones relative bearing to a known location (the beacon).

The term electric beacon includes radio, infrared and sonar beacons.

Radio beacons

A radio beacon is non-directional transmitter at a known location, that usually transmits a constant signal on a specified radio frequency. In addition most beacons transmit some form of self-identification.

Radio beacons have many applications, including air and sea navigation, propagation research, robotic mapping, radio frequency identification (radio-frequency identification, RFID) and indoor guidance as with real time locating systems (RTLS). In some applications beacon functions are combined with telemetry transmission.

Radio navigation beacons

Main article: Non-directional beacon

A most basic aviation radio navigational aid is a the NDB 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 techonlogy and installed at coastal areas, for use by ships at sea (Appleyard 1988). Most of them are no longer in service, while some have been converted to telemetry transmitters for differential GPS.

In addition to dedicated radio beacons, any AM, VHF, or UHF radio station at a known location can also be used as a beacon with direction finding equipment.

Radio propagation beacons

File:DRA5.jpg
QSL card from DRA5 radio propagation beacon

These are mostly amateur radio beacons that are used to study the propagation of radio signals. They can be found on HF, VHF, UHF and microwave frequencies. The microwave beacons are also used as signal sources to test antennas and receivers.

Regularly updated lists of amateur radio beacons operating on HF and 50 MHz are maintained by Martin Harrison G3USF and Joost Schuitemaker, ZS5S (see references). A list of propagation beacons on 70 MHz is maintained at "The 4 metres website" [1]. There is no comprehensive and regularly updated directory for amateur radio beacons operating on 144 MHz and above, due to the local scope of their transmissions. A list for VHF/UHF beacons in Europe is maintained by Erwin Witt, DK5EW.[2]

The International Beacon Project, which is coordinated by the Northern California DX Foundation (NCDXF) and the International Amateur Radio Union (IARU), consists of 18 HF propagation beacons worldwide, which transmit in turns on 14100, 18110, 21150, 24930 and 28200 kHz [3].

As part of an International Telecommunications Union (ITU) funded project (Resolution ITU-R 27)[4], radio propagation beacons were installed at Sveio, Norway (callsign LN2A) and at Darwin, Australia (callsign VL8IPS). The beacons operated on frequencies 5471.5, 7871.5, 10408.5, 14396.5 and 20948.5 kHz [5]. Since 2002 there have been no reception reports for these beacons and the relevant ITU web pages have been removed, so they are classified as "non-operational".

Single letter HF beacons

Main article: Letter beacon

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 frequencies. There is no official information available about these transmitters. Some investigators suggest that some of these beacons (the so called "cluster beacons") are actually radio propagation beacons.

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, transmitting FSK telemetry on 2276.0 MHz[1]

Driftnet buoy radio beacons

Distress radiobeacons

Main Article: Distress radiobeacons

Distress radiobeacons, also collectively known as distress beacons, emergency beacons, or simply, beacons, are those tracking transmitters that operate as part of the international Cospas-Sarsat Search and Rescue satellite system. When activated, these beacons send out a distress signal that, when detected by non-geostationary satellites, can be located by triangulation. 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 into the signal (thus providing both instantaneous identification & position.) distress signals from the beacons are homed by Search and Rescue (SAR) aircraft and ground search parties who can in turn come to the aid of the concerned boat, aircraft, 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" [6] (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, the term beacon signifies a kind of wireless data which carries the SSID, the channel and security protocols such as WEP (Wired Equivalent Protection) or WPA (Wi-Fi Protected Access) along with it in a non-directional way. Beacons are simple radio frequency signals emitted by simple wireless devices, such as wireless SOHO routers which emit beacons ranging from 2.4 GHz to 5 GHz varying channel 1 to 11 but the channel 1, 6 and 11 are low interference channels. See [7] and [8]

Infrared beacon

Sonar beacon

See also

Template:Nautical portal

References

  1. ^ Jessop, G.R., G6JP (1983). VHF-UHF manual (4th Edition ed.). RSGB. p. 2.19. ISBN 0-900612-63-0. {{cite book}}: |edition= has extra text (help)CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link)

Further reading

  • Godfrey Manning (2007). "Sky High: ADF and NDBs". Radio User. 2 (12). PW Publishing Ltd: 25. ISSN 1748-8117. {{cite journal}}: Unknown parameter |month= ignored (help)
  • Godfrey Manning (2008). "Sky High: NDB/ADF". Radio User. 3 (1). PW Publishing Ltd: 24–25. ISSN 1748-8117. {{cite journal}}: Unknown parameter |month= ignored (help)
  • John Jaminet, W3HMS and Charlie Heisler, K3VDB (2007). "Bulding a beacon for 2401 MHz". CQ VHF. 10 (3). CQ Communications, Inc: 44–46. ISSN 1085-0708.{{cite journal}}: CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link)
Retrieved from "https://en.wikipedia.org/w/index.php?title=Radio_beacon&oldid=192609899"