Circuit arrangement for displacing the clutter spectrum in a radar receiver

Claim 1

A circuit arrangement for a receiver of a pulse-Doppler-radar with a fixed clutter filter and with a pre-connected device for the displacement of the clutter spectrum and with a circuit for the determination of the mean change of the phase to prevent interfering low frequency received clutter signals during consecutive radar periods for producing a control signal for displacement of the clutter spectrum, in particular for radar devices with a non-constantly scanning antenna, characterized in that the received clutter signals are supplied by way of two parallel circuit branches to a phase shifting device (PS1) at the output of the circuit arrangement, with one circuit branch containing the circuit for determining the mean change of the clutter phase (MCA) and which is part of a regulating loop and contains a memory (TPA) which is connected to the output of the regulating loop, and the other circuit branch contains a delay line (VE) which has a delay which extends over several (n) radar periods and the regulating loop of the first circuit branch includes in series an adjustable phase shifting device (PS2), the circuit for the determination of the mean change of the clutter phase (MCA), an accumulator (AKU) and a return loop (RFS) from the output of the accumulator (AKU) to the adjustable phase shifting device (PS2) and the circuit for the determination of the mean change of the clutter phase (MCA) and the accumulator (AKU) are connected through a switch (SA1), which is closed at the end of a radar period, and the accumulator (AKU) and the following memory (TPA) are connected through a further switch (SA2) which is closed after a number of several (n) radar periods corresponding to the delay in the delay device (VE).