Efficient Motion Compensation Approach with Modified Phase Correction for Airborne SAR

Airborne synthetic aperture radar (SAR) image quality considerably degrades because of motion errors. High precision motion compensation (MOCO) is necessary in an advanced SAR data processing scheme. Operation complexity and computation burden are both increased as development of ultra-high resolution SAR. There are two main disadvantages for conventional MOCO. Firstly, accurate envelope correction should be performed by complicated interpolation, expending a large number of computing resources. In addition, interpolation makes a separate process, which could not be integrated into imaging algorithms easily. Secondly, since the fixed processing flow of conventional MOCO, phase correction is seriously influenced by the accuracy of envelope correction. An efficient MOCO approach is presented in this paper. A novel calculation formula of line-of-sight (LOS) range displacement is introduced from another perspective. On this basis, modified phase correction turns to be performed before envelope correction, on the premise that the accuracy of signal phase should be guaranteed. Consequently, an approximate envelope correction without interpolation can be adopted using subswath, to improve the processing efficiency. Simulations with point targets and processing of real data are used to confirm the validity of the proposed approach.