Phase Recovery for 3D SAR Range Focusing

The problem of calibrating Synthetic Aperture Radar (SAR) data for 3D image formation will be investigated here. A source of errors in modern radar systems is inaccurate range estimations, during the data collection. This is caused by two ambiguities in the platform location and the scene topography map. Such range estimation errors induce some asynchronization in the dechirping process, i.e. a shift in the range direction. When such an error is small, the final image will be blurred and possibly compensated using conventional autofocus techniques. In multipass SAR image formation, this error between the passes is large and we need a different machinery to correct it. We formulate the problem of SAR pulse compression with the range estimation error, in a general setting. The range estimation error appears as some structured phase error in the phase history. We then introduce a new phase recovery technique for compensating the phase error. Some simulation results show the capabilities of the introduced method.