Self-focusing method for high-resolution moving ship SAR imaging

Abstract

The invention discloses a self-focusing method for high-resolution moving ship SAR imaging. The method comprises the following steps: carrying out coarse compensation and range direction matched filtering processing on a baseband echo signal by adopting inertial navigation data; coarsely focusing the imaged original image; screening out a plurality of strong scattering regions from the original image, and respectively estimating a local phase error of each strong scattering region by using a weighted phase gradient self-focusing method; calculating a coefficient matrix of a second-order errorpolynomial; constructing coordinate vectors X and Y of the whole original image, and fitting a phase error of each pixel point at each slow moment by utilizing a coefficient matrix; and compensating the original image by adopting the phase error estimation matrix. According to the invention, the problem that a traditional self-focusing method cannot perform unified estimation compensation on space-variant phase errors caused by ship motion during moving ship imaging is solved, and accurate focusing of moving ship high-resolution imaging is achieved.

Description

technical field [0001] The invention relates to the technical field of synthetic aperture radar imaging, in particular to a self-focusing method for high-resolution moving ship SAR imaging. It can be used for self-focusing processing of moving ship imaging by airborne, missile-borne and other radar platforms. Background technique [0002] Synthetic Aperture Radar (SAR), as an active microwave active sensor, can obtain two-dimensional images of the observation scene all day, all day long and from a long distance, and has been widely used in various radar carriers. However, due to the movement of the ship within the beam irradiation time, the ship target in the SAR image will appear defocused; at the same time, with the improvement of the resolution, the pixel points occupied by the large ship target in the SAR image are getting smaller and smaller. However, the ups and downs of each part of the ship under the influence of wind and waves are different, which makes it difficul...

AI Technical Summary

Problems solved by technology

However, in the high-resolution SAR imaging of ship targets on the sea, due to the movement of the ship within the coherent processing time (CPI), unknown motion errors not only exist in the radar platform, but also in the ship target, so the traditional autofocus method cannot Meet the needs of high-resolution imaging of ships

At the same time, in recent years, most of the research on the self-focusing of moving ship imaging needs to calculate the phase error of pulse by pulse through one-dimensional search, and the phase error of each pulse needs to be iteratively estimated multiple times, the process is complicated and the calculation amount is large. There are certain limitations

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