Patent US 4,062,012

A radar signal processor employs digital circuits to provide two adaptive resholds which act to reject clutter and noise. A digital constant false alarm unit serves to set the first threshold level by comparing an expected false alarm number with a number of noise pulses occurring in a noise gate generated during the radar dead time. The second threshold is set by establishing a background average. The existence of a target in a particular range cell in relation to the second threshold is determined by comparing its hit count with the hit counts of two range cells proximately following it and the two range cells proximately preceding it. A target is automatically acquired in range and velocity by using a memory unit and constructing a velocity-range matrix which identifies range and velocity by pattern recognition techniques.