Autofocusing of SAR images based on RELAX

An autofocus algorithm based on RELAX is presented. Assuming that there exist multiple dominant scatterers in each range bin, the algorithm performs the phase error correction and the parameter estimation of the dominant scatterers alternatively by adopting an iterative procedure. The proposed algorithm does not require that the clutter and noise in each range bin to be of certain distribution model, and it can be used to estimate all kinds of phase errors. Thus the proposed algorithm is robust for most kinds of scene content. The results obtained in autofocusing experiments on real SAR/ISAR data show that the algorithm is very efficacious.