Apparatus for radar

A radar apparatus operative to selectively filter ambiguous echoes, comprising:

• a transmitter operative to transmit electromagnetic pulses in varying pulse repetition intervals;
• range gates operative to receive energy impulses reflected by at least one object;
• a Doppler filter operative to work with an impulse function response having a length that is significantly shorter than a predetermined number of periods and thereby to produce for a received impulse a number of outgoing impulses, wherein upon the appearance in the radar of a representative single impulse for a plurality of echoes, the Doppler filter emits an output impulse that is significantly shorter than the output impulse signal caused by a first of the echoes;
• and
• at least one threshold device that, irrespective of the amplitudes of the representative single impulses, generates fewer incidences of threshold exceeding than a corresponding first-time-around impulse, thus producing output impulses for a plurality of pulse intervals, with the radar being operative to ascertain the differences between the incidences of threshold exceeding and to use these as the basis for the filtering.