Synthetic aperture radar clutter reduction system
First Claim
1. A method for reducing clutter in synthetic aperture radar (SAR) images of the ocean surface, the method comprising the steps of:
- obtaining spotlight mode SAR images of a selected patch of the ocean surface;
computing an estimate of the ocean surface parameters of the patch of the ocean surface as it was at the time that the spotlight mode SAR images were obtained; and
modifying the spotlight mode SAR images, based on the ocean surface parameters, to remove distortion effects caused by movements in the ocean surface, and to produce clutter-reduced SAR images.
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Abstract
A method, and corresponding apparatus, for deriving clutter-reduced images of the ocean surface in synthetic aperture radar (SAR) systems. An estimate of ocean surface parameters is first made and subsequently updated iteratively, to provide a reliable model of a selected patch of the ocean as it existed when a series of conventional spotlight mode SAR images were obtained. Based on the estimated ocean model, and on models of ocean wave behavior, of radar scattering behavior, and of the SAR acquisition system, predicted SAR images can be generated, and compared with the measured SAR images, and clutter-reduced images can be produced as a result. In addition to the clutter-reduced images, the method and apparatus of the invention produce an accurate estimate of ocean surface data, and can be used in a reliable approach for detecting hard targets on the ocean.
81 Citations
16 Claims
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1. A method for reducing clutter in synthetic aperture radar (SAR) images of the ocean surface, the method comprising the steps of:
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obtaining spotlight mode SAR images of a selected patch of the ocean surface; computing an estimate of the ocean surface parameters of the patch of the ocean surface as it was at the time that the spotlight mode SAR images were obtained; and modifying the spotlight mode SAR images, based on the ocean surface parameters, to remove distortion effects caused by movements in the ocean surface, and to produce clutter-reduced SAR images. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. Apparatus for reducing clutter in synthetic aperture radar (SAR) images of the ocean surface, the apparatus comprising:
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a SAR system for obtaining spotlight mode SAR images of a selected patch of the ocean surface; and a clutter reduction processor, including an ocean model, based initially on a guessed set of ocean surface parameters, means for computing, based on the ocean model, an estimate of the ocean surface parameters in,the patch of the ocean surface as it was at the time that the SAR images were obtained, means for comparing the estimated ocean surface parameters with the actual SAR images, means for updating the ocean model if the comparison made by the means for comparing is not favorable, whereby .the ocean model is repeatedly updated until the comparison is favorable, and means for modifying the SAR images to diminish effects of clutter caused by the ocean surface. - View Dependent Claims (15, 16)
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Specification