Electric beacon
From Wikipedia, the free encyclopedia
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.
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.[citation needed] See [1] and [2]
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[edit] Radio beacon
A radio beacon is non-directional transmitter that usually transmits a constant signal on a specified radio frequency.
Before the days of VOR, GPS, LORAN, beacons were used for map localization. In any case, they are nowadays used for robotic mapping, radio frequent identification (radio-frequency identification, RFID) and indoor guidance as with real time locating systems (RTLS).
[edit] Types of Radio Beacons
There are several different kinds of beacons.
In aviation there is a beacon called NDB or Non-directional Beacon. These are used to help find airports and conduct instrument approaches. These beacons will be decommissioned over the next few years as they have been replaced with newer better technologies.
There also in the past were marine beacons for use at sea (Appleyard 1988), but most cases these no longer are in service.
There are also amateur radio beacons that are used to test propagation of radio signals.
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.
Any AM, VHF, or UHF radio station can also be used as a beacon with direction finding equipment.
[edit] 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"[3] (the first 24 hours following a traumatic event) when the majority of survivors can still be saved.
[edit] Infrared beacon
[edit] Sonar beacon
[edit] See also
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[edit] References
- Martin Harrison, G3USF. G3USF's Worldwide List of HF Beacons. Retrieved on 2008-01-05.
- Martin Harrison, G3USF. G3USF's Worldwide List Of 50 MHz Beacons. Retrieved on 2008-01-05.
- Thomas M. Rösner, DL8AAM (2005). The DL8AAM QSL Collection: QSLs from Radio Beacons. Retrieved on 2008-01-05.
- Appleyard, S.F.; Linford, R.S. and Yarwood, P.J. (1988). Marine Electronic Navigation (2nd Edition). Routledge & Kegan Paul, 68-69. ISBN 0-7102-1271-2.
[edit] External links
- An Accurate and Cheap Navigation System for Robots, using sonar beacons.
- Minimum-resource distributed navigation and mapping, using IR beacon.
- International Beacon Project, the IARU worldwide network of HF propagation radio beacons, by NCDXC.de:Funkfeuer
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