Walter R. Fried

Peer Reviewed

Abstract: This paper traces the history of the development and applications of Doppler radar navigation systems from their inception in the mid-1940s to the present. The early design concepts, problems, tribulations, and obstacles are discussed. With only noncoherent pulse radar transmitters available at that time, a unique technique of self-coherence had to be invented and implemented in order to allow Doppler signal extraction. Similarly, the severe leakage problems of continuous wave (CW) radars had to be overcome. In spite of these problems, both pulse Doppler and CW Doppler radar navigation systems were successfully developed and produced. The next problem needing a solution was the measurement of negative velocity as required in helicopter operation. This lead to the development of coherent pulse and frequency modulated (FMKW Doppler radars and new frequency trackers, with wide application for navigation and hovering indication over land and water. The development and production of Doppler systems for the commercial airlines followed, and these systems were used for civil over-ocean navigation for many years. A Doppler radar was used for velocity measurement on the Surveyor and the Appollo Lunar Excursion Module for the achievement of soft landing on the moon. Most modem military helicopters and strategic aircraft, as well as many drones, are currently implemented with Doppler navigation radars, and this is likely to continue. In addition, the Doppler navigation radar concepts have been applied to the so-called precision velocity update (PVU) mode of conventional military airborne search and tracking radars.
Published in: NAVIGATION: Journal of the Institute of Navigation, Volume 40, Number 2
Pages: 121 - 136
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