Iterative Phase Unwrapping for Phase-Interferometric Moving Target Detection in SAR

In an interferometric phase SAR image, all points on the ground nominally appear as a continuum of phase differences while the moving targets appear as discontinuities. The authors have previously shown that it is possible to detect moving targets in the SAR by detecting such phase anomalies. To detect the anomalies, one first fits a plane through the phase-difference image and then looks for substantial deviations from this plane. When the phase centers on the receiver are widely separated, the phase image has multiple foldovers and it is first necessary to unwrap the phase before a plane can be fitted. However, standard phase unwrapping schemes often fail because of the noisy nature of the phase differences. This paper describes an iterative scheme for unwrapping the phase image specifically developed for this application.