OMEGA
Omega was developed by the U.S. Navy in 1957 to be used as a long-range worldwide continuous radionavigation system. Operating at a very low 10.2 kHz to 13.6 kHz, there are 8 stations in the system labeled A through H. The system utilizes a 10-second broadcast format with each station broadcasting sequentially for approximately 1 second. Like Decca, it establishes its hyperbolic pattern through the use of phase comparison. Each hyperbolic line borders an Omega lane with an approximate distance of 8 miles at the baseline. The radio signals can indicate very accurately where you are within the lane (percent oflane), it is the receiver that must keep track of which lane you are in. This is the major disadvantage of the system.
To utilize the Omega system, you must first begin by synchronizing the receiver with the incoming signal at the origin of the voyage. As the vessel gets underway on its path of travel, the receiver counts the lanes it passes through. As long as the signals are strong and nothing interrupts the functioning of the receiver, the lane count is reasonably accurate. Should something interfere with signal reception, the receiver can lose count of the lanes. Omega navigational receivers were developed with a tracking graph that provided the user with a visual indication that the system was working continually.
The system was difficult to use, and became less commercially viable after Transit satnav was introduced. Because the system operates long range, it was also extensively dependent upon skywaves and readings needed to be corrected from Omega propagation tables. The system still has the primary advantage of being continually available almost anywhere on the face of the earth with an effective working range of not less than 600 miles to a station nor more than 7,000 miles from a station. Application of readings is the same as in Loran and Decca on special overprinted charts. Information concerning the system's operation can be obtained from listening to radio station WWV or WWVH, the same stations that broadcast time information.
