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Amplitude calibration of a stepped-chirp signal for a synthetic aperture radar

  • US 10,107,895 B2
  • Filed: 09/19/2014
  • Issued: 10/23/2018
  • Est. Priority Date: 09/19/2014
  • Status: Active Grant
First Claim
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1. A Radar Calibration Processor (“

  • RCP”

    ) for calibrating the amplitude of a stepped-chirp signal utilized by a synthetic aperture radar (“

    SAR”

    ) to produce SAR display images, the RCP comprising;

    a periodic amplitude error (“

    PAE”

    ) calibrator;

    a first non-periodic amplitude error (“

    NPAE”

    ) calibrator; and

    a second NPAE calibrator,wherein the first NPAE calibrator is in signal communication with both the PAE calibrator;

    wherein the PAE calibrator is configured to receive video phase history (“

    VPH”

    ) data from the SAR and, in response, produces PAE calibrated data from the VPH data and wherein the VPH data includes a plurality of steps within a stepped-chirped waveform and a range frequency; and

    wherein the PAE calibrator is further configured to perform an azimuth compression on the VPH data to produce azimuth compressed input data, concatenate the azimuth compressed input data into concatenated data, define functional descriptions for optimization of the azimuth compressed input data, establish an error model based on the functional descriptions, search for optimum coefficients of one or more Legendre polynomials to determine a minimum image quality metric (“

    IQM”

    ) for the error model, determine an estimated PAE using the optimum coefficients of the error model, and apply the estimated PAE to the azimuth compressed input data.

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