Radar ranging system for use with sloping target

A signal processing system for use with a radar ranging system which transmits a radio frequency beam of finite angle to a sloping target of not greater than some known slope and creates from the return signal a beat frequency signal comprising various frequencies corresponding to the various distances from the ranging system to the target. The processing system includes a first tracking bandpass filter which is caused to seek and lock onto the lowest frequency FL in the beat frequency signal. Given frequency FL, the angle of the beam and the maximum slope of the target, a theoretical maximum frequency FX is computed. A second tracking bandpass filter tracks down from frequency FX to and locks onto frequency FH, the frequency component in the beat frequency signal associated with the maximum range to the target. From frequencies FL and FH and the beam angle, the average range to and/or slope of the target can be computed.