Analysis of Target-Speed Determination with Doppler Radar

The response of the Doppler radar speed meter was analyzed when there were two or more targets in a radar beam. When there are two targets of equal size and equal speed there is a fading condition and under a special condition, the radar becomes inoperative. When many targets with various speeds and sizes appear in a radar beam, the speed-meter output will fluctuate and the output represents either the speed of one of the targets or the average speed of all of them or something else. The speed meter is not likely to register the speed of the target with the highest speed as commonly believed. There is no theoretical assurance that the speed meter is registering the wanted target´s speed. The fading condition, the fading period, the speed-meter fluctuation frequency, and the speed-meter response to the actual target speeds were theoretically analyzed. Traffic-police radar was mainly used for examples.