Use of Matched Airborne Omega Receivers For Rendezvous

Abstract

Automatic airborne Omega receivers are rapidly becoming available for military, civil, and general aviation aircraft. The transmitter network will offer worldwide cover in 1974/75. Consequently a universal reference environment will be available to facilitate rendezvous navigation, and production sensors will be already fitted in some aircraft, or economically obtainable. Differential Omega operation for terminal and rendezvous navigation has been discussed and studied for some time; the problems with its implementation have not been with the technical merit of the scheme, but rather with the methods of obtaining and disseminating the propagation correction information. For pure rendezvous navigation, both normal and differential corrections could be omitted, however, this approach would negate the operational advantages of the receivers for enroute navigation, and make ambiguity resolution on a 3- frequency system impossible. By using receivers with matched propagation corrections the conflict can be avoided, and rendezvous to the order of 200 yards obtained, retaining optimal enroute capability. The receivers need not be of the same make, model, or price class, provided a controlled match of propagation prediction characteristics is obtained. While present automatic receivers tend to use a variety of proprietary techniques for propagation correction, and the simpler receivers to use tables or preprogrammed values, the prediction data all basically comes from the same source: the NavOceano programme and conductivity map. It is therefore practical to make fully-automatic airborne Omega receivers, covering a wide price and performance range, with matched propagation models and thus near-ideal rendezvous performance, at no sacrifice in enroute performance. With the continuing improvement in prediction knowledge, and the common use of this knowledge by several manufacturers, an equally good match between receivers of different makes is considered a reasonable goal.