A SAR image near-coast surface clutter and its azimuth blur suppression method

Abstract

A SAR image near-coast surface clutter and its azimuth ambiguity suppression method, the SAR image acquisition of the same scene area is carried out by radar at different times, and n pieces of SAR images with different time dimensions are obtained, and the obtained n pieces of different time dimensions are obtained Fourier transform of the SAR images along the time dimension to obtain n SAR images in the spatial frequency domain. The stationary targets and their range and azimuth fuzzy energy in the n spatial frequency domain SAR images are all accumulated in the spatial frequency domain Zero-frequency position, remove the zero-frequency position in the spatial frequency domain, and perform incoherent superposition on the remaining SAR images along the spatial frequency domain axis to obtain a pure oceanic SAR image after removing stationary clutter and azimuth blur. The present invention completes static ground object clutter filtering through multi-temporal SAR images, can suppress azimuth ambiguity without loss of azimuth resolution, and can completely remove stationary ground clutter and its azimuth ambiguity without losing ocean moving target information Energy, to prevent leakage alarm phenomenon.

Description

technical field [0001] The invention relates to the field of synthetic aperture radar signal processing, in particular to a multi-temporal SAR image-based clutter of near-shore objects and a method for suppressing azimuth ambiguity. Background technique [0002] Synthetic aperture radar technology has the characteristics of all-weather and all-weather, and it is a widely used remote sensing technology for ground observation. Azimuth ambiguity is a major problem faced by synthetic aperture imaging radar, which is an inherent defect of SAR system. [0003] At present, there are a large number of research methods at home and abroad to remove azimuth ambiguity from SAR data. The traditional method is to suppress the sidelobe energy by using an azimuth filter to achieve azimuth ambiguity suppression. The relevant patents that can be found include "A method for azimuth ambiguity suppression for synthetic aperture radar" (application number: CN201711449591.0 ), "A SAR orientation...

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Problems solved by technology

The relevant patents that can be found are "A Method for Suppressing Spaceborne Synthetic Aperture Radar Strip Mode Azimuth Ambiguity" (application number: CN201310428893.5), but this method also loses some existing information when performing azimuth filtering

With the introduction of the concept of SAR over-navigation, Leng Xiangguang et al. proposed a method for removing near-shore azimuth blurring based on multi-temporal SAR images. Azimuth Blur Removal Method" (Application No.: CN201810033162.3), this method finds out the blurred area through the strong correlation of the ground-based source and target of two SAR images according to the autocorrelation difference between the ground clutter and its azimuth blur and the moving sea surface, Then the blurred position is removed by the binarization method, and the blurred area is restored by the image patching algorithm. Although this method can remove the azimuth blur caused by the clutter near the coast to some extent, when the blurred area covers When there is useful information on the sea surface, this method also removes this useful information at the same time, which undoubtedly produces a false alarm phenomenon when detecting near the coast

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