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Method and system for moving target elimination and indication using smoothing filters

  • US 4,168,500 A
  • Filed: 03/10/1972
  • Issued: 09/18/1979
  • Est. Priority Date: 03/10/1972
  • Status: Expired due to Term
First Claim
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1. In a monopulse radar system, a null command generator fed by the in-phase and quadrature sum and difference signals derived from target reflections received at monopulse antennas comprising:

  • a. a first subtracting circuit fed by the in-phase sum and difference signals;

    b. a second subtracting circuit fed by the quadarature sum and difference signals;

    c. a first summing circuit fed by the in-phase sum and difference signals;

    d. a second summing circuit fed by the quadrature sum and difference signals;

    e. a third summing circuit fed by the first and second subtracting circuits;

    f. a fourth summing circuit fed by the first and second summing circuits;

    g. means for delaying the output of the third summing circuit by a time value τ

    d, where τ

    d is a value equal to the distance between the antenna phase center divided by the product of 4 times the product of the aircraft velocity and the target azimuth;

    h. means for advancing the output of the fourth summing circuit by τ

    d ;

    i. a first bank of narrow band filters fed by the delaying means;

    j. a second bank of narrow band filters identical to that of the first bank fed by the advancing means;

    k. means for phase differencing corresponding filters of the first and second banks of narrow band filters;

    l. a plurality of means for smoothing the outputs of the phase differencing means; and

    m. means for averaging the outputs of the smoothing means.

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