GEO SAR Squint Imaging Based on Variable Receive Window Opening Time

Compared with geosynchronous synthetic aperture radar (GEO SAR) operating in broadside mode, GEO SAR squint mode can improve the response ability to emergency events. However, GEO SAR is faced with a lot of data redundancy and serious 2-D space variation when operating in squint mode. In this paper, an efficient echo acquisition method is proposed and range-Doppler azimuth chirp scaling (RD-ACS) algorithm is given to compensate 2-D spatial variation. By adjusting the opening time of the receive window reasonably, the range cell migration of the target is greatly reduced, and the coupling between range and azimuth is reduced. The edge of the scene is defocused when the 2-D spectrum of the center point of the scene is used as the reference function to complete the bulk phase compensation. The slant range model coefficient, which varies with the shortest distance, is selected and brought into the imaging process to complete the range spatial variation compensation. Then the higher order disturbance function is introduced to compensate the azimuth spatial variation, which will introduce additional errors, which need to be compensated in the RD domain. Finally, the correctness of the proposed algorithm is verified by experiments.