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Range/azimuth ship imaging for ordnance control

  • US 4,546,354 A
  • Filed: 06/17/1982
  • Issued: 10/08/1985
  • Est. Priority Date: 06/17/1982
  • Status: Expired due to Fees
First Claim
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1. In conjunction with an airborne synthetic aperture radar system having an interferometer antenna and a range versus azimuth angle display, a method for forming with improved azimuth resolution a scaled range/azimuth image of a ship target under the influence of sea state conditions comprising the steps of:

  • (a) steering the pointing of the interferometer antenna boresight to provide radar illumination of the ship target;

    (b) controlling the range sampling timing so that corresponding samples from pulse-to-pulse over the coherent integration interval correspond to the same range increment of the ship target;

    (c) compensating for phase variations in the received signals due to the respective motions of the radar bearing aircraft and the ship;

    (d) measuring interferometrically the compensated received signals for each doppler filter in each range bin;

    (e) plotting as interferometer azimuth angle versus filter doppler frequency the measured data for each doppler filter in each range bin;

    (f) performing a weighted least squares linear regression straight line fit to the plotted data points of the azimuth angle/doppler distribution for each range bin;

    (g) determining the slope of the straight line fit to the azimuth angle/doppler distribution for each range bin;

    (h) averaging the slope values determined over all range bins; and

    (i) determining from the averaged slope value the values of predetermined system parameters including synthetic aperture radar integration time and doppler filter bandwidths and spacings to be used predictively in the succeeding coherent integration interval in forming the range/azimuth image.

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