A Novel PF-Based Method for Height Reconstruction in Distributed Geosynchronous Repeat-Pass InSAR.

With the advantages of high spatial resolution, short repeat-pass cycle, and large observation area in Ka-band distributed geosynchronous (GEO) synthetic aperture radar (SAR) systems, its interferometry (InSAR) measurement can fast retrieve high-resolution and high-accuracy digital elevation model (DEM). However, compared to low-orbit systems, it is more difficult and costly for distributed GEO SAR systems to perform tight formation flying at such a high orbit altitude, and, therefore, atmospheric effects, which bring nonstationary and non-Gaussian phase errors, should be taken into account in its repeat-pass InSAR. To address the problems earlier, a spatial-temporal joint particle filter-based method (ST-PF) for DEM generation by distributed GEO InSAR is proposed in this article. The proposed ST-PF method is validated under several stationary and nonstationary atmospheric conditions through simulation experiments, and high-accuracy and high-resolution DEMs are obtained. Moreover, the ST-PF method can withstand severe nonlinearity in interferometric phases, which results from a relatively small ambiguity height in the Ka-band. It is also tested that the mean square error (MSE) of the retrieved DEM is consistent with the posterior Cramer-Rao bound (pCRB) of the estimation problem, showing the validity and the accuracy of the proposed ST-PF method. With various processing parameters, errors, and scene types tested, the method shows good robustness in different conditions.