Patent US 4,058,809

An airborne early warning moving target indicator radar in which targets in the main beam having reflective characteristics sufficient to override side lobe attenuation are tracked relative to the side lobes and the residual doppler frequency for such targets resulting from side lobe detection calculated. Based on this calculation, the appropriate ones of a bank of doppler filters are inhibited at the appropriate range bin to prevent a false target indication without inhibiting the display of moving targets in the main beam at the same range but having different doppler frequencies. In addition to side lobe blanking, an automatic gain control circuit is provided in which the interpulse period is divided into a large number of equal time intervals on the order of 0.4 microseconds each to thereby separate the return signal from each radar pulse into a large number of range bins. The gain of a wide band return signal amplifier is separately adjusted for each range bin on the basis of the sampled amplitude of the return signal from the preceding radar pulse in the corresponding range bin to thereby provide optimum gain without saturating the return signal processor. A novel amplifier and method of digitally controlling the gain thereof is disclosed as is the superimposition of the gain adjustment transients of each stage of the amplifier.