Traffic monitoring system

A traffic monitoring system has a common housing for a Doppler radar transceiver, a video camera, and a digital computer for processing the Doppler signal. The system also includes a video cassette recorder, a high-speed photographic camera, and a laptop computer for downloading control settings and a program from a diskette or memory card to the digital computer. The digital computer performs an initial self-test by injecting a calibration signal in lieu of a Doppler signal into an electronic interface between the radar transceiver and the digital computer. The radar transceiver generates a Doppler signal having two channels, and the phase between the channels indicates whether a vehicle is approaching or receding from the radar transceiver. The two channels are recorded on the left and right audio channels of the video cassette. Recorded with the video signal is a push-down stack of speeds of vehicles detected on the system, in order to present a record of prevailing traffic conditions when prosecuting a speed violator. The recorded picture may also include a series of successive speed measurements for each vehicle. Although an operator could listen to the Doppler signal, it is preferred that the digital computer activates an audio annunciator to emit a click sound when the system detects a vehicle, and a warbly sound when a detected vehicle exceeds a specified speed limit.