TABLE OF CONTENTS The range Doppler algorithm (RDA) was developed in 1976 1978 for processing SEASAT SAR data [1 8]. The first digitally processed spaceborne SAR image was made with this algorithm in 1978 [9], and it is still in widespread use today. The algorithm is designed to achieve block processing efficiency, using frequency domain operations in both range and azimuth, while maintaining the simplicity of one-dimensional operations. It takes advantage of the approximate separability of processing in these two directions, allowed by the large difference in time scales of the range and azimuth data, and by the use of range cell migration correction (RCMC) between the two one-dimensional operations.
Block processing efficiency is also achieved for the RCMC operation because it is done in the range time and azimuth frequency domain. This domain is called the "range Doppler" domain, since azimuth frequency is synonymous with Doppler frequency. The algorithm is called the range Doppler algorithm, because the fact that RCMC is performed in this domain is the most distinguishing feature of the algorithm.
Energy from point targets, at the same range but separated in azimuth, is transformed to the same location in the azimuth frequency domain. Therefore, correction of one target trajectory in this domain effectively corrects a family of target trajectories that have the same slant range of closest approach. This is a key feature of the algorithm, which allows RCMC to be implemented efficiently in the range Doppler domain.
For implementation efficiency, all matched filter convolutions are performed as multiplies...
