Method for deblurring radar range-doppler images
AssigneeLockheed Martin Corporation
InventorsHarry Urkowitz, Jeff D. Cammerata
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Abstract
A method for displaying information relating to the range and Doppler of a remote target includes transmitting electromagnetic energy toward the target, and receiving reflected signals defining a two-dimensional (range-Doppler) radar image. The reflected signals are matched-filtered, which tends to blur the image. The image is deblurred while the features of thermal noise enhancement and irregularity of the deconvolved output are constrained to produce a single point deblurring output.
Claims24
A method for displaying at least one of range and Doppler of a moving remote target, said method comprising the steps of:
- generating return radar signals from at least one moving target;
- from said return radar signals, generating a two-dimensional image by matched linear filtering, which matched linear filtering is based upon maximization of the peak amplitude of combined set of pixels of the two-dimensional image, which undesirably spreads the resulting pixels of the image in both dimensions to produce a point spread function;
- performing a coherent deblurring of the image including its point spread function to produce a deblurred image, by filtering with coefficients derived from a least-squares criterion wherein phase information of the signals is preserved during the coherent deblurring;
- and
- displaying at least one of range and Doppler information from said deblurred image.
A method for displaying information relating to a target, said method comprising the steps of:
- transmitting radar signals toward said target;
- receiving reflected radar signals from said target;
- processing said reflected radar signals using a pulse-compression filter to produce a first two-dimensional radar image;
- establishing a noise limit for the signals of said image;
- establishing a maximum irregularity for deconvolved signals of said image;
- establishing a desired deconvolved image;
- processing the reflected radar signals and the desired deconvolved image through a least squares fit to provide a deblurred output image in which noise does not exceed the noise limit and the shape does not exceed the maximum irregularity;
- and
- displaying or otherwise using the deblurred output image.
A method for displaying information relating to a remote target, said method comprising the steps of:
- transmitting radar signals toward the target, to thereby generate return signals;
- applying the return signals to a compression filter, to thereby generate compressed return signals;
- generating I and Q signals from the compressed return signals to thereby generate an image with dimensions of range and Doppler, which image is subject to blurring attributable to the compression filter;
- imposing constraints on noise of a desired deblurred image;
- imposing constraints on roughness of the desired deblurred image;
- generating a transform of the desired deblurred image;
- taking a DFT of the transform of the desired deblurred image, to thereby generate the desired deblurred image;
- and
- displaying or otherwise using information relating to the deblurred image.
A method for deblurring a radar image of a target, the method comprising:
- matched filtering radar signals returned from the target to generate a two-dimensional image of the target;
- and
- coherent deblurring the two-dimensional image to produce a deblurred image, by filtering with coefficients derived from a least-squares criterion wherein phase information of the signals is preserved during the coherent deblurring.
A system for deblurring a radar image of a target, the system comprising:
- a matched filter for generating a two-dimensional image of the target from radar signals returned from the target;
- and
- a deblurring filter for performing a coherent deblurring of the two-dimensional image to produce a deblurred image, by filtering with coefficients derived from a least-squares criterion wherein phase information of the signals is preserved during the coherent deblurring.
Dependencies are inferred from the claim text.