A SAR Processing Algorithm With No Interpolation

Current SAR processing algorithms incorporate interpolators to perform key functions. It turns out that the interpolators are difficult to implement, and are one of the largest sources of error in the processing. In this paper, we introduce a new algorithm which eliminates the use of the interpolation operation, yet achieves accurate range migration correction over the full range swath. The algorithm can handle large apertures and large squints, and has noticeably better phase and geometry accuracy than current algorithms, even when the apertures and squints are high. The new algorithm is called the Differential Range Deramp - Frequency Domain (DRD-FD) Algorithm, because its key operation is to use the linear-FM property of the range chirp to differentially shift the range energy as a function of azimuth frequency, and then to do the remaining range cell migration correction in the two-dimensional frequency domain. In this paper, the new algorithm is described, and simulation results are given to demonstrate its focussing, phase and geometric performance with squinted SAR data. In addition, an image is shown made from SEASAT data.