| 摘要 |
<p>HARMONIC DETECTOR FOR TRAFFIC RADAR A traffic radar unit capable of operation from a moving patrol vehicle has a receiver provided with phase recognition circuitry that prevents the display of "ghost" readings. After initial processing of the incoming composite Doppler signal, the phase recognition circuitry receives logic conditioned, low and high frequency speed signals derived from the Doppler signal and produces an abort command to prevent the determined target speed from being displayed if the phase relationship between the two speed signals remains constant for a predetermined number of cycles of the low frequency speed signal. The latter signal corresponds to a low frequency component of the Doppler signal representing the speed of the patrol car, but the high frequency signal may be a harmonic that would produce an invalid reading. The circuitry employs a serial to parallel type shift register having a data input receiving the high frequency speed signal. The register is clocked by the low frequency speed signal. If all outputs of the shift register assume the same logic level, phase coherence(and hence a harmonic relationship) is recognized and the display is aborted to prevent ghost readings from stationary objects such as road signs; mixed outputs indicate a valid target (moving target vehicle) and the reading is displayed. (Docket 394)</p> |
