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 of America in cooperation with six partner nations.
The OMEGA radionavigation system, developed by the United States Navy for military aviation users, was approved for full implementation in 1968 and promised a true worldwide oceanic coverage capability 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]
When 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, France, Japan and Australia. Coast Guard personnel operated two U.S. stations - one in LaMoure, North Dakota and the other in Haiku, Hawaii.
There were eight Omega stations: Bratland, Norway (A), Paynesville, Liberia (B), Kaneohe, Hawaii (C), LaMoure, North Dakota (D), Chabrier, Réunion (E), Trelew, Argentina (F),Woodside, Australia (G) and Shushi-Wan, Japan (H). The station in Australia was originally intended for New Zealand but was moved to Australia after protests from anti-war protestors.
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 nm using the principle of phase comparison of signals.[2]
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 an extremely low frequency station for submarine communications.
Antennas
Image:Reunion Omega antenna site 20.975S 55.2873E.png 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.
See also
Alpha, the Russian counterpart of Omega Navigation System, still in use.