Doppler Frequency Analysis of Radar.
Abstract:
A Doppler radar is adapted to respond only to walking human targets by providing means to detect the frequency modulation of the Doppler signals caused by the oscillatory body movements of such walking targets. A frequency locked loop frequency modulation detector is provided for efficient detection of this so-called step frequency modulation, and the detected step frequencies are split into several bands representing targets walking at different step rates. Circuitry is shown for adapting this technique to continuous wave radars or range gated radars. This so called step frequency is detected by mean of a specially selected frequency modulation detector and circuitry is provided for splitting the step frequency signals into several bands corresponding to targets stepping at different speeds, for example, the lowest steping frequency may correspond to a slow walking man and the highest to a running man. The invention can be utilized with radars with or without range measuring capability. Author