Doppler tracker for a spaceborne ScanSAR system

This paper presents a methodology for tracking the Doppler parameters in long swaths of ScanSAR signals. The approach is entirely developed around the physical model of the Doppler effect, parameterized in terms of the spacecraft attitude angles. A new, combined algorithm is designed to estimate yaw and pitch and resolve the PRF (pulse repetition frequency) ambiguity using all available, current, and past, return samples. It is shown that the variance of the Doppler centroid (DC) estimates can be brought down to the low single-digit Hz level with computationally simple estimation algorithms.