Abstract:

The jointly autofocus algorithm of range shift and phase error for motion compensation of a high resolution synthetic aperture radar (SAR) is proposed to solve the problematic motion error in airborne SAR imaging. The algorithm focuses on the estimation of motion errors, and it can not only estimate the high order motion error but also correct the range shift and phase error simultaneously. This paper utilizes the entropy of a 2-dimensional (2-D) SAR image as the objective function, and establish the optimization function with respect to the polynomials of the motion error. Meanwhile, a damped Newton algorithm is used to solve the function for the polynomials, and both errors are compensated. Additionally, the algorithm strategy with alternate autofocus is designed to achieve robust motion error compensation in an accurate way. Raw data experiments validate the proposed method.