Circuit for speed measurement of vehicles according to the Doppler-radar principle

摘要

A circuit for speed measurement of vehicles according to the Doppler- radar principle wherein a Doppler-useful signal is evaluated in a computer to which such signal is infed by means of a threshold value switch. A single sideband modulator is provided, at the input side of which there is supplied the Doppler-useful signal and also a high- frequency signal produced by a high-frequency oscillator. The output side of the single-sideband modulator is connected with the input of a phase- locked loop, the output signal of which is converted into the original frequency band of the Doppler signal by means of a demodulator connected at its output side with the input of the threshold value switch.