Efficient motion compensation of SAR imagery by refocusing approach

Current motion compensation algorithms for a moving object on synthetic aperture radar (SAR) imagery by refocusing are accurate, but they suffer from a severe computational efficiency problem. If the step size of an assumed target velocity is too large, one could miss the true target velocity, whereas too small a step size would lead to a considerable computation load. To address this issue, the way motion error affects a compressed signal should be understood. In this paper, we briefly mentioned the concept of velocity correlation function (VCF) to describe the sensitivity of a SAR compressed signal to motion error, and derived its analytical model. After conducting a sensitivity study based on the model, the VCF was generalized to a velocity correlation map, which visualizes a sensitivity of the SAR system parameters to target motion in both the range and the azimuth directions simultaneously. In addition, a sensitivity study of the VCF of some real SAR sensors including ALOS-2 was also conducted.