A Beam Rotation Error Compensation Method for TOPS SAR Data Imaging

Synthetic aperture radar (SAR) working at the terrain observation with progressive scan (TOPS) mode can obtain wide-coverage images. The improvement of image coverage makes further demands for higher radiation accuracy. However, traditional imaging algorithms do not take into account the effects of errors introduced by beam rotation, resulting in poor radiometric deterioration and distortion of image quality. This letter focuses on the specific manifestations of this phenomenon and the reasons for its formation. To improve the TOPS SAR image quality, a method based on the generalized cross correlation (GCC) of subsignals is presented to estimate the parameters of beam rotation in this letter. Experimental results with real spaceborne TOPS SAR data are provided to validate the analysis of this phenomenon and show that the proposed method improves the radiation accuracy for more than 0.2 dB.