Nonhomogeneous clutter suppression based on terrain elevation interferometric phase compensation in multi-satellite formation systems

Abstract

In multi-satellite formation synthetic aperture radar (SAR) systems, the nonhomogeneous clutter problem arising due to the terrain elevation interferometric phase is a crucial factor that degrades clutter suppression performance. We propose a clutter suppression method based on terrain interferometric phase compensation (TIPC) that can overcome this problem. The method can be summarised as a rough-and-refined two-step phase compensation framework. In the rough-compensation stage, the terrain interferometric phase is estimated using similar phase samples in a local area. To ensure that more candidate samples are considered, a novel sample-selection window is designed based on fringe direction and density; its shape and size can be adjusted adaptively based on the fringe morphology. For refined topographic phase compensation, an error feedback weighting correction structure is designed to compensate for the fringe detail loss. The weighting coefficient is constructed based on coherence, phase residual distribution, and fringe structure features, which can be adapted to adjust the contribution of the phase estimation error. Moreover, to improve the topographic phase compensation performance, the proposed method can be applied iteratively. Finally, clutter suppression was performed after the TIPC processing. The experimental results demonstrate that the proposed method can obtain higher topographic phase compensation precision and better clutter suppression performance than conventional methods.