A high squint imaging method for mid-orbit SAR based on joint time-frequency resampling

Abstract

The invention discloses a mid-orbit SAR high squint imaging method based on time-frequency joint resampling. The echo data with the same movement in the azimuth direction; the range migration correction processing is performed on the echo data with the same distance migration of the target in the azimuth direction to obtain the echo data in the range-Doppler domain; the azimuth is performed on the echo data in the range-Doppler domain Frequency-domain re-sampling processing to obtain echo data after space-variation correction; azimuth Fourier inverse transform is performed on echo data after space-variation correction to obtain time-domain echo data; geometric correction is performed on time-domain echo data, Get the final mid-orbit SAR image. The present invention corrects the third-order and high-order spatial variations through the azimuth-frequency domain interpolation method. Compared with the existing mid-orbit SAR high squint imaging method, the present invention can reduce some approximations in the SAR imaging process and improve the accuracy of SAR imaging .

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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