Abstract: In a pulse doppler radar system which provides dynamic correction to variable radar echo return signals from clutter end targets using a block adaptive signal regulator (BASR) and a fast Fourier transform (FFT), a gain restoration circuit is used to optimize the gain corrected amplitudes over a plurality of time samples so that the tendancy of larger targets to obscure the return signals of smaller targets is minimized. The BASR conventionally evaluates the amplitude of echo returns in each time sample before it enters the FFT, by determining if they exceed the radar receiver's dynamic range, and dividing all samples by 2.sup.N when a sample exceeds the dynamic range (where N equals a shift number which signifies a shift by the BASR). The gain restoration circuit feeds information which indicates the number of BASR shifts to the output of the FFT as a function of range gate.

Abstract: In combination with an envelope detector in a radar system, a bias compensation circuit consisting of a programmable read-only memory and a binary adder produce an unbiased envelope detection signal. The bias compensation circuit adds one to the output of the detector based upon whether the minimum of the I and Q (inphase and quadrature) signals is odd and the maximum even. It is capable of compensating for both normal envelope detection and the multiple divide-by-two case. As a result the dynamic range of the radar can be increased without the necessity for extensive additional hardware.

Abstract: A doubly adapative constant false alarm rate (CFAR) apparatus utilizing a doubly adaptive detector which is based upon the use of an auxiliary parallel adaptive detector in addition to the conventional main adaptive detector. The auxiliary adaptive detector has a lower threshold setting. The threshold crossing rate of the auxiliary detector, which depends upon the clutter statistics, is used to adjust the base multiplier setting of the main detector.