Amplitude calibration of a stepped-chirp signal for a synthetic aperture radar
First Claim
Patent Images
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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Abstract
A Radar Calibration Processor (“RCP”) for calibrating the amplitude of a stepped-chirp signal utilized by a synthetic aperture radar (“SAR”) is disclosed. The RCP includes a periodic amplitude error (“PAE”) calibrator, first non-periodic amplitude error (“NPAE”) calibrator in signal communication with the PAE calibrator, and a second NPAE calibrator in signal communication with the first NPAE calibrator.
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Citations
22 Claims
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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; anda 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; andwherein 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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
- RCP”
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11. A method for calibrating the amplitude of a stepped-chirp signal utilized by a synthetic aperture radar (“
- SAR”
) to produce SAR display images, the method comprising;estimating a periodic amplitude error (“
PAE”
);estimating a first non-periodic amplitude error (“
NPAE”
); andestimating for a second NPAE calibration after the first NPAE (“
NPAE-1”
) has been estimated; andwherein estimating the PAE includes receiving video phase history (“
VPH”
) data from the SAR andproducing a PAE calibrated data from the VPH data in response to receiving the VPH data and wherein the VPH data includes a plurality of steps within a stepped-chirped waveform and a range frequency. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
- SAR”
-
22. 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;means for estimating a periodic amplitude error (“
PAE”
);means for estimating a first non-periodic amplitude error (“
NPAE”
) after the estimating the PAE; andmeans for estimating a second NPAE after estimating the first NPAE, wherein the means for estimating first NPAE is in signal communication with both the means for estimating the PAE and the means for estimating the second NPAE.
- RCP”
Specification