Abstract: A circuit for a pulse Doppler radar receiver in which a measuring signal for determining the mean frequency of disturbing low frequency received clutter signals is obtained from which there is determined a control signal for operating a circuit that precedes the clutter filter and serves to displace the clutter spectrum into the blocking ranges of the fixed clutter filter particularly for radar devices having a non-constantly scanning antenna and wherein the circuit for determining the mean change in the clutter phase is in parallel with a delay device which has a delay that extends over a number of radar periods and wherein the circuit for determining the mean change in the clutter phase is preceded by an adjustable phase shift device which is followed by an accumulator for the addition of phase change and wherein continuous adjustment of an adjustable phase shift device is accomplished with a return loop and in which a switch is provided between the circuit for determining the mean change in the clutter pha