HOS based algorithm for autofocusing of spotlight SAR images

The authors propose a novel SAR (synthetic aperture radar) image autofocusing technique based on higher order statistics (HOS) analysis. The SAR imaging system has been modelled as a bandlimited complex linear time invariant (LTI) filter, so the autofocusing problem is equivalent to the problem of reconstructing the phase of a bandlimited complex LTI system. The complex transfer function of the imaging system is recovered from the estimated bispectrum of the received data by means of an ad-hoc algorithm.