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PHOTOS OF EIGHT OMEGA NAVIGATION STATIONS - WORLD WIDE
"Auroral Chorus IV" is my largest online natural VLF radio-phenomena compendium album on Internet Archive (begun in 2010 and ongoing uploads to 2017).
More than half of the MP3 audio files on this page are field-recordings of Earth's "Natural VLF Radio" signals and are quite beautiful. //
search: 259 gorvgeious_whistlers_Fish_Rock_Rd_nCA_02Apr94_pt1 -- VLF including Omega audio
In 1971, the United States Navy launched the Omega navigational system for submarines and surface ships. The system used radio frequencies and phase difference calculations to determine global position. A network of eight (VLF) transmitter sites spread around the globe made up the system, which required the cooperation of six other nations.
Omega’s fix accuracy was somewhere between one and two nautical miles. Her eight transmitter stations were positioned around the Earth such that any single point on the planet could receive a usable signal from at least five stations. All of the transmitters were synchronized to a Cesium clock and emitted signals on a time-shared schedule.
LOP-thumbA ship’s receiving equipment performed navigation by comparing the phase difference between detected signals. This calculation was based around “lanes” that served to divvy up the distance between stations into equal divisions. A grid of these lanes formed by eight stations’ worth of overlapping signals provides intersecting lines of position (LOP) that give the sailor his fix.
In order for the lane numbers to have meaning, the sailor has to dial in his starting lane number in port based on the maps. He would then select the pair of stations nearest him, which were designated with the letters A to H. He would consult the skywave correction tables and make small adjustments for atmospheric conditions and other variances. Finally, he would set his lane number manually and set sail.
You timed your question well - in exactly a week we will have the 20th anniversary of the Omega system permanent shutdown.
Kritchlow said: ↑
What exactly is "Omega"? ...Is the signal transmitted from the ground?
Not is but was. We are taking past tense here. Yes, a number of countries participated to have this almost global aviation/oceanic global navigation system through system of ground antennas/transmitters. The best positional accuracy you could achieve was about 3-4 miles. VLF don't 'bounce', they hug the terrain, can go around mountain ranges, all that by the principle of diffraction. My atomic watch today is also getting 'synced' up using (similar) LF signal (antenna in Fort Collins, Co). Omega receiver was a small suitcase -like box and I bet you needed a trained operator. I think (I could be wrong) Omega was ultimately much more popular on water than in the air.
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.
When the eight station chain became operational, 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. 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, am Omega receiver could locate a position to within 4 nm using the principle of phase comparison of signals. In the Royal Canadian Navy, the OMEGA system was used in the AOR, 280 and Halifax class ships.
This web page is intended to review hyperbolic radionavigation systems of the past. The systems featured here are specific to my area of interest.