Fast Back-Projection SAR Processing Using Non-Uniform FFTs

Abstract

The back-projection (BP) algorithm is a SAR processing approach that uses time-domain convolution of the SAR data in order to perform SAR focusing. Some benefits of this approach are exact inversion, ideal motion compensation including topography information and handling of general aperture geometries. However, it has the main drawback of a high computational burden. The fast back-projection (FBP) and the fast factorized back-projection (FFBP) algorithms circumvent this limitation without a significant performance loss by choosing a polar grid to perform the processing, which adapts better to the signal properties. In order to increase its efficiency, the non-uniform FFT (NUFFT) is used to perform the large amount of interpolations that need to be carried out. The modifications to process data acquired with a circular trajectory are also included. Results with real data acquired by DLR’s E-SAR system are shown to validate the proposed algorithms.