Synthetic aperture radar processor to handle large squint with high phase and geometric accuracy
First Claim
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1. A digital signal processing method for focusing samples of two-dimensional signals reflected form targets in a synthetic aperture radar or analogous system, the samples representing azimuth lines (columns) and range lines (rows), the method comprising the steps of:
- (a) transforming the azimuth lines from the signal domain to the frequency domain;
(b) rotating the phase of each sample in the range-signal, azimuth-frequency domain to make the zero-range-frequency loci of each target congruent with each other target;
(c) transforming the range lines form the signal domain to the frequency domain;
(d) rotating the phase of each sample in the range-frequency, azimuth-frequency domain so that after step (e) the range energy is focused, and aligned in the azimuth direction;
(e) transforming the range lines from the frequency domain to the image domain;
(f) rotating the phase of each sample in the range-image, azimuth-frequency domain, so that after step (g) the azimuth energy is focused; and
(g) transforming the azimuth lines from the frequency domain to the image domain.
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Abstract
A digital signal processor for synthetic aperture radar (SAR) data comprising a method of implementing range cell migration correction without the use of an interpolator, and a method of applying phase corrections and memory management to accommodate large squint in the radar sensor. With this method, the image quality of the processed SAR image is improved, particularly in regard to phase and geometric registration.
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Citations
12 Claims
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1. A digital signal processing method for focusing samples of two-dimensional signals reflected form targets in a synthetic aperture radar or analogous system, the samples representing azimuth lines (columns) and range lines (rows), the method comprising the steps of:
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(a) transforming the azimuth lines from the signal domain to the frequency domain; (b) rotating the phase of each sample in the range-signal, azimuth-frequency domain to make the zero-range-frequency loci of each target congruent with each other target; (c) transforming the range lines form the signal domain to the frequency domain; (d) rotating the phase of each sample in the range-frequency, azimuth-frequency domain so that after step (e) the range energy is focused, and aligned in the azimuth direction; (e) transforming the range lines from the frequency domain to the image domain; (f) rotating the phase of each sample in the range-image, azimuth-frequency domain, so that after step (g) the azimuth energy is focused; and (g) transforming the azimuth lines from the frequency domain to the image domain. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification