Other formats

    Adobe Portable Document Format file (facsimile images)   TEI XML file   ePub eBook file  


    mail icontwitter iconBlogspot iconrss icon

Salient. Victoria University of Wellington Students' Newspaper. Volume 31 Number 15, July 9, 1968

What Omega is — Tony Hurst (doing PhD in Physics)

What Omega is — Tony Hurst (doing PhD in Physics)

Omega is basically a navigation system. A craft receives signals from a pair of transmitting stations and by comparing the times at which the signals arrive, it is able to find the difference between the distances to the two stations from the craft.

By doing this with two pairs of stations, any craft can find its position to within one mile by day, or two miles by night. (These are the accuracies claimed by the U.S. Navy).

Several navigation systems of this type already exist, such as Loran, DECCA and the Transit satellite system. The satellite system, which is now operational, is more accurate than Omega. Fixes however are not available on demand, but only every hour or so when a satellite passes.

The unique advantage of the Omega system is that it is a Very Low Frequency (VLF) system, and VLF radio waves can penetrate 50-100 feet under water. This means that Polaris submarines can check their position by means of Omega without breaking the surface and being exposed to Radar. This is the reason for the concern over the establishment of an Omega base in New Zealand.

Government officials claim that Polaris submarines do not need Omega because they have inertial guidance systems which do not need to pick up any external signals. Commercially available inertial navigation systems are so poor that they could benefit from an Omega check every hour, and it is likely that military systems are so much better that they do not need a check every few days, but the actual accuracies are classified.

The Northrop Company, which has so far won the main Navy contracts for this system. is installing several million dollars worth of Omega equipment in Polaris submarines. as well as several hundred sets in the U.S Navy aircraft.

The accuracy obtainable with Omega depends largely on the cost of the receiving installation. The military installations, which contain multiple receivers linked to computers, can be more accurate than the 1 mile quoted, whereas the simple receivers in the several thousand dollar class are liable to be inaccurate by several miles, and what is more, they take several minutes to get a fix, during which time a commercial jet aircraft will fly 30 odd miles. (For any fix to be meaningful to one mile in a jet aircraft, it must be taken in a time of six seconds, the period the jet takes to go one mile.) The commercial use of the Omega system would thus appear to be limited.

Omega is a purely passive system as far as the craft finding its position is concerned. Therefore in theory anyone with reasonable technical competence can use it. However, if the need arises the US can alter the characteristics of the system so that those not in the know cannot use it. This can be done using the master control station of the system, the American Government station WWVL. in various subtle ways, such as changing sequencing of the station or the time lags between stations, which even the operators of the station are not likely to notice. The operators of the station do not actually control it. it is always automatically locked to received signals. Even the possibility of such changes would presumably deter any powers which the US regards as unfriendly from using the system militarily.

Overall, the Omega system appears to be a sophisticated system which at present is primarily military. To talk only of Polaris submarines could well be misleading however. NZ is not in a position that an Omega base here would be a threat to Russia, and even China is a long way away (rather further than the Chinaphobes seem to think).

The sort of use which our Omega base is likely to be put to in the immediate future. if it is established, is controlling the bombardment of Vietnam by American ships and planes.

page 10

Photo of students talking to a police officer

Photo of a man picking up rubbish from the ground

Photo of Keith Holyoake