An Improved Imaging Algorithm for High Resolution Spaceborne Squinted Sliding Spotlight SAR

摘要

An improved imaging algorithm is proposed for processing high resolution spaceborne squinted sliding spotlight SAR data in this paper, which includes four steps, namely, azimuth preprocessing, coarse focusing, fine focusing and geometry correction. In the azimuth preprocessing, a linear range walk correction (LRWC) filter is used to mitigate the two-dimensional (2-D) spectral skew, and a modified subaperture method is performed to increase the size of the subaperture data, and obtain the 2-D spectral without aliasing. Then the modified ω-k kernel is used to realize coarse focusing. However, the equivalent velocities vary both in range and azimuth, caused by the earth rotation and LRWC, resulting in the targets unfocused except the target at the center position. Thus, the fine focusing step is applied to compensate the residual phase errors. Finally, the geometric correction is adopted to correct the geometrical distortion. The computer simulation results verify the validity of the proposed imaging algorithm.