Omega Navigation

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OMEGA NAVIGATION SYSTEM Operating Frequency: VLF 10 to 14 kHz

Transcript of Omega Navigation

Page 1: Omega Navigation

OMEGA NAVIGATION

SYSTEMOperating Frequency: VLF 10 to 14 kHz

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• the first truly global radio navigation system for aircraft.

• It enabled ships and aircraft to determine their position by receiving very low frequency (VLF) radio signals transmitted by a network of fixed terrestrial radio beacons, using a receiver unit.

• It became operational around 1971 and was shut down in 1997.

OMEGA

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OMEGA - History• John Alvin Pierce, the

"Father of Omega," first proposed the use of continuous wave modulation of VLF signals for navigation purposes in the 1940's.

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OMEGA - History• After experimenting with

various frequencies, he  settled on a phase stable, 10 kHz transmission in the 1950's. Thinking this frequency was the far end of the radio spectrum   Pierce dubbed the transmission "Omega," for the last letter of the Greek alphabet.

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OMEGA• There were eight Omega transmitting

stations, located in Norway, Liberia, Hawaii, La Réunion, Argentina, Australia, USA, and Japan.

• The very-low-frequency signals from the transmitters were detected by a ship's navigation receiver, and slight differences (phase differences) between the signals indicated the position of the receiver.

• The system was accurate to within 4 km/2.5 mi during the day and 7 km/4 mi at night.

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OMEGA• Omega was a Cold War inspired long range

navigation system which expanded the principles of Decca and Loran. It used synchronized, ultra-low frequency radio to create a globally intersecting grid of Lines of Position (LOP's) which could penetrate underwater.

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OMEGA - Operation Signal Characteristics

• Omega utilized CW (continuous wave) phase comparison of signal transmission from pairs of stations. The stations transmitted time-shared signals on four frequencies, in the following order: 10.2 kHz, 11.33 kHz, 13.6 kHz, and 11.05 kHz. 

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OMEGA- Operation• Each Omega station transmitted a very low

frequency signal which consisted of a pattern of three/four tones unique to the station that was repeated every ten seconds.

• If an Omega receiver picked up signals from three stations, it would compute a vessel's location by phase comparison. This means that the receiver determined what direction each signal from was coming from; the vessel was at the point where the bearing to Station A intersected the bearings to Stations B and C.

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OMEGA- Accuracy• Omega was very accurate for its time. In the late

1960s, when Omega began operation, navigation was generally the result of a comparison of a dead reckoning position (the computed position of the vessel) with the results of "shooting a star" with a preset sextant. Navigators had to compute the difference between the position preset from the dead reckoning position and the position obtained by observation. This method was accurate, with errors of not more than 1 nautical mile, but required about 20 minutes to take three "star shots" and do the math for each.

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OMEGA - Advantages• By comparison, the Omega signals penetrate not

only water but also sea ice to at least 15 meters, making the very risky business of surfacing completely unnecessary.

• The very low frequency (VLF)transmissions of Omega would be almost completely unaffected.

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OMEGA• 1.) Cable from the

antenna is coming in from left to right to the pulley at the base of the tower(Red Circle). From there it follows the white arrow to the top of the tower. The cable then goes down to the counter weight, through that pulley and back up to be secured at the top of the tower.2.) Ladder running to the top of the tower.3.) Counterweight rails. .

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Omega Tower Paynesville, Liberia

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OMEGA - Terminationo The Omega Navigation System website, operated by the

U.S. Naval Observatory, says it all: "As of September 30, 1997, 0300 UT, the OMEGA Navigation System terminated. All eight OMEGA stations, NORWAY (A), LIBERIA (B), HAWAII (C), NORTH DAKOTA (D), LA REUNION (E) ARGENTINA (F) AUSTRALIA (G) AND JAPAN (H)) around the world have permanently ceased to operate... OMEGA, the first world wide radio navigation system, operated for over twenty-six years. Users must no longer depend on OMEGA broadcasts for navigation of any kind."