OMEGA Navigation System
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OMEGA is the name for the first truly global radio navigation system for aircraft, operated by the United States in cooperation with six partner nations.
OMEGA was originally developed by the United States Navy for military aviation users. It was approved for development in 1968 and promised a true worldwide oceanic coverage capability with only eight transmitters and the ability to achieve a four mile accuracy when fixing a position. Initially, the system was to be used for navigating nuclear bombers across the North Pole to Russia. Later, it was found useful for submarines.[1]
Each Omega station transmitted a very low frequency signal which consisted of a pattern of four tones unique to the station that was repeated every ten seconds. Because of this and radionavigation principles, an accurate fix of the receiver's position could be calculated. OMEGA employed hyperbolic radionavigation techniques and the chain operated in the VLF portion of the spectrum between 10 to 14 kHz. Near its end, it evolved into a system used primarily by the civil community. By receiving signals from three stations, an Omega receiver could locate a position to within 4 nautical miles using the principle of phase comparison of signals.[2]
Omega stations used very extensive antennas in order to transmit their extremely low frequencies. Specifically, they used grounded or insulated guyed masts with umbrella antennas, or wire-spans across fjords. Some Omega antennas were the tallest constructions on the continent where they stood or still stand.
When six of the eight station chain became operational in 1971, day to day operations were managed by the United States Coast Guard in partnership with Argentina, Norway, Liberia, and France. The Japanese and Australian stations became operational several years later. Coast Guard personnel operated two US stations; one in LaMoure, North Dakota and the other in Haiku, Hawaii. Due to the success of the Global Positioning System the use of Omega declined during the 1990s, to a point where the cost of operating Omega could no longer be justified. Omega was permanently terminated on September 30, 1997 and all stations ceased operation.
The LaMoure station is now used by the United States Navy as a very low frequency station for submarine communications.
[edit] OMEGA stations
There were eight Omega stations in total:
- Bratland, Norway (station A ; ), fjord-span antenna
- Omega transmitter Trinidad (station B until 1976, replaced by station in Paynesville, Liberia) )
- Paynesville, Liberia (station B ; ): It was inaugaurated in 1976 and used as radio antenna an umbrella aerial mounted on a 417 metre high guyed mast of lattice steel, which was the tallest structure ever built in Africa. The station was directed to the government of Liberia after the termination of the Omega Navigation System on September 30, 1997. As of February, 2006, the Omega Tower near Paynesville is still standing, although it is unused. Access to the tower is not restricted, and it is possible to climb it.
- Kaneohe, Hawaii (station C ; ): One of two stations operated by the USCG.
- La Moure, North Dakota (station D ; ): The other station operated by the USCG. It used a 365.25 metre tall guyed mast as an antenna. Since the shutdown of the Omega Navigation System, it is used for VLF transmissions to submarines.
- Chabrier, Réunion (station E ; ): used a 428 metre tall guyed mast.
- Trelew, Argentina (station F ; ): a 366 metre high guyed steel mast situated at Golfo Nuevo, 40 km outside Trelew. It was the tallest construction of South America. On June 23 1998 it was demolished after the OMEGA service was shut down.
- Woodside, Australia (station G, now known as VLF transmitter Woodside ; ): The station in Australia was originally intended for New Zealand but was moved to Australia after protests from anti-war protestors. An umbrella aerial is used, which is carried by a 432 metre high steel framework guyed mast. This mast is the highest construction in the southern hemisphere, which may change if a proposed Solar updraft tower in Buronga near Mildura is built. Since the shutdown of OMEGA it is used as a transmitter for orders to submarines at 13 kHz.
- Shushi-Wan, Japan (station H ; ): located on Tsushima Island: a 389 metre tall mast, the highest construction in Japan.
[edit] See also
- Alpha, the Russian counterpart of Omega Navigation System, still in use as of 2006.
- LORAN, low frequency terrestrial radio navigation system, still in use.
- CHAYKA, the Russian counterpart of LORAN.
