LAUSR

Abstract. Entropy-based parametric autofocus is commonly applied to correct the residual azimuth phase error (APE) that arises from the residual motion errors (RME) in synthetic aperture radar. However, the image’s entropy trends to a convex function only when a great number of range bins are selected according to the law of large numbers, which means that the average residual APE is finally obtained via this method for the space-variant characteristics of RME. A two-stage parametric autofocus algorithm is carried out to derive the exact residual APE with several range bins selected for iteration. To this end, a new objective function in the first stage is designed to reduce the number of local solutions and protect targets from energy leaking. In the second stage, the filled function is imported to jump out of the current solution to a more optimal one until no other optimal solution exists. In the final part, both simulated and real data experiments validate the performance of the proposed method.