Abstract: Radar systems that operate in accordance with the crossfeed method require an exact balancing of the individual Doppler frequency evaluation channels in the receiver. According to the invention, a special method is used first to make the amplitude levels in the individual channels equal to one another and then to determine and balance the phase differences between the channels. A radar system using this method is also described.

Abstract: 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.

Abstract: A method of checking or testing the functionality of transmitter-receiver reversing switches of pulse Doppler-radar installations for protecting the microwave-receiver component, testing being accomplished by means of a microwave-test signal supplied to the microwave-receiver component between the antenna and the transmitter-receiver reversing switches. According to the invention, the Doppler angle error voltages brought about by such microwave-test signal is measured once with and once without the radar transmitter turned-on, there is formed the difference signal between both of the momentarily measured Doppler angle-error voltages, and when there occurs such a difference signal there is concluded that there is present a defective transmitter-receiver reversing switch.