H. Buell

Peer Reviewed

Abstract: Simple Doppler radar dead-reckoning navigation systems of medium accuracy (l-2%) have recently been developed for helicopters, and are now being applied extensively. Helicopters because of their low cost and large numbers, cannot afford the more sophisticated costly navigation systems used in larger fixed-wing aircraft. Doppler radar navigation systems have many design features that are of particular importance to helicopters. They are self-contained and require no external aids, so that they can operate in remote areas that have no such aids. They require no lengthy warm-up or initialization before take-off, or the use of special alignment tools, and thus meet the scramble requirements of military helicopters. Their navigation accuracy, at helicopter speeds, is comparable to currently available medium performance inertial systems costing two to three times more. Kearfott has developed for the U.S. Army a Lightweight Doppler Navigation System (LDNS) which has the nomenclature of AN/ASN-128. The LDNS weighs under 30 pounds and has a predicted MTBF of over 2000 hours. It has a navigation accuracy of 1.3% (CEP) when supplied with heading from the helicopter’s magnetic compass with an accuracy of one degree (one sigma). The AN/ASN-128 is now in production for the U.S. Army, and for military forces outside the United States. Some modifications have been made to the LDNS to meet specific requirements of these nations, including software and hardware; a typical version of the LDNS will be described in detail to illustrate the performance and flexibility of the basic LDNS design.
Published in: NAVIGATION, Journal of the Institute of Navigation, Volume 27, Number 2
Pages: 124 - 131
Cite this article: Buell, H., "DOPPLER RADAR SYSTEMS FOR HELICOPTERS", NAVIGATION, Journal of The Institute of Navigation, Vol. 27, No. 2, Summer 1980, pp. 124-131.
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