Digital motion compensation system for radar platforms

Claim 1

A digital motion compensation system for providing error correction signals for radar platforms comprising an I detector receiving a reference signal and radar echo signals, a phase shifter shifting said reference signal 90*, a Q detector receiving said radar echo signals and said 90* phase shifted reference signal, a digital MTI filter receiving the output from said I detector, an analog to digital converter receiving an output signal from said Q detector, a polarity circuit simultaneously receiving signals from said digital MTI filter and said analog to digital converter, said polarity circuit producing a positive output whenever its two inputs are identical, a divide circuit receiving simultaneously signals from said polarity circuit and said analog to digital converter, a pair of unipolar detectors, one receiving a signal from said I detecTor and the other a signal from said Q detector, an AND circuit, means to determine whether the I signal from said pair of unipolar detectors is greater than the Q signal, the output therefrom being a first signal to said AND circuit, means to determine whether the Q signal is less than a preselected threshold signal, the output therefrom being a second signal to said AND circuit, means to accumulate a preselected number of echo signals to thereupon provide an actuating output signal being a third signal to said AND circuit, means to provide a signal representative of a preselected minimum radar range being a fourth signal to said AND circuit, said AND circuit upon receipt of said first, second, third, and fourth signals providing an output signal; a gate circuit receiving the output signals from said divide circuit and said AND circuit, summing means receiving the output from said gate circuit, a digital to analog converter receiving the output from said gate circuit, and a voltage controlled oscillator receiving a signal from said digital to analog converter to provide said error correction signals.