Mid-orbit SAR high squint imaging method based on time-frequency joint resampling

Abstract

The invention discloses a mid-orbit SAR high squint imaging method based on time-frequency joint resampling. The method comprises the steps: the target echo data are collected; azimuth time domain resampling is performed on the target echo data so as to obtain the echo data with the same range migration in azimuth direction; range migration correction is performed on the echo data with the same range migration in azimuth direction so as to obtain the range-Doppler domain echo data; Right; azimuth frequency domain resampling is performed on the range-Doppler domain echo data so as to obtain echo data after space variation correction; azimuth Fourier transform is performed on the echo data after space variation correction so as to obtain the time domain echo data; and geometric correction isperformed on the time domain echo data so as to obtain the final mid-orbit SAR image. The azimuth frequency domain interpolation method is applied to correct the third-order and high-order space variation, and certain approximations in the SAR image process can be reduced and the SAR imaging accuracy can be enhanced in comparison with the existing mid-orbit SAR high squint imaging method.

Description

technical field [0001] The invention belongs to the technical field of radar signal processing, and in particular relates to a mid-orbit SAR high squint imaging method based on time-frequency joint resampling. Background technique [0002] For a long time, low-orbit SAR has played an important role in the observation of the earth, but the ability to continuously observe the earth is poor. High-orbit SAR is a good supplement to the existing space-borne observation platform, but the launch of high-orbit The cost of satellites is high, and limited by the spatial resolution, it is difficult to use them on a large scale. In contrast, the performance of medium-orbit SAR is relatively balanced, and it has good continuous observation capabilities and moderate resolution. In order to observe a larger and wider area, the working mode of the existing medium-orbit SAR is usually in the squint mode. However, so far, there are few domestic studies on medium-orbit SAR high-squint imaging....

AI Technical Summary

Problems solved by technology

[0004] Although the above mid-orbit SAR imaging methods can achieve mid-orbit SAR high-squint imaging, these methods have grating lobes in the imaging results of block processing, or there are many approximations in the process of time-frequency transformation and scale change, which leads to the accuracy of mid-orbit SAR imaging. Low

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