AN ADVANCED DSS-SAR INSAR TERRAIN HEIGHT ESTIMATION APPROACH BASED ON BASELINE DECOUPLING

Abstract

In the distributed small satellites synthetic aperture radar (DSS-SAR), baseline is usually coupled, that is, along-track baseline and across-track baseline exist simultaneously. However, coupling baseline makes it di-cult to distinguish phase difierences caused by terrain height and Doppler frequency difierence. In SAR interferometry (InSAR) geometric model, across-baseline is necessary to bring interferometric phase to estimate terrain height. Oppositely, along-track baseline will bring extra phase difierence and dramatically decrease the accuracy of terrain height estimation. Considering the aforementioned problem, this paper focuses on the study of baseline decoupling of DSS-SAR. We flrstly analyze the efiect of coupling baseline on terrain height estimation, and then propose the method of baseline decoupling through space projection theory. In order to realize baseline decoupling, equivalent slave satellite, equivalent baseline, and equivalent slant range are deflned through projecting slave satellite on range-height plane of master satellite. Furthermore, based on our baseline decoupling, an advanced approach of estimating terrain height is presented, which is more efiective than traditional InSAR geometric model. Simulation results illuminate that the baseline decoupling can eliminate along-track baseline efiect on terrain height estimation efiectively and conflrm the validity and e-ciency of terrain height estimation approach proposed in this paper.