SEARCH AND RESCUE USING NAVAID RETRANSMISSION

Retransmission of radionavigation signals can be used to determine the position of a party needing rescue, in somewhat the same manner as it is used to track weather ballons and drifting ocean buoys. Such a concept equips the rescue radio/beacon transmitter with the "front end" of a radionavigation receiver, and locates the computer and display portion of the radionavigation receiver with the receiver of the rescue signals. The selection of a particular navaid depends on the particular application. Aspects to be considered include waiting time, coverage, accuracy, and cost, as well as ambiguities, preprocessing, and the relay link. This paper discusses the use of seven major signal sources: Omega, Loran-C, Russian Omega, VLF communications, sferics, and the NAVSTAR GPS.