Influence of Orbit and System Parameters on Geosynchronous SAR Multiple-Aperture Interferometry Processing: Analysis and Validation

A geosynchronous synthetic aperture radar (GEO SAR) can achieve a shorter revisit time, a longer observation time, and a larger coverage area for the target scene compared with low earth orbit (LEO) SARs. Therefore, its combination with the multiple-aperture interferometry (MAI) technique can allow along-track deformation measurements with better performance. Nevertheless, because the orbit and system parameters determine the MAI measuring geometry, their influence on the accuracy of such deformation measurements should be extensively studied. In this paper, based on theoretical deductions and simulations, the performance of GEO SAR MAI processing in along-track deformation measurements is discussed considering the orbit and system parameters. The optimal along-track deformation accuracy (OADA) was introduced for quantitative performance evaluations. Finally, a repeat-track global navigation satellite system-based SAR MAI experiment, implemented with a transponder onboard displacement device on the ground and BeiDou-2 inclined geosynchronous orbit satellites, was conducted to verify the effectiveness of the proposed method and its validating analysis. The results suggested that the OADA could be improved by decreasing the azimuth antenna size or the ratio between the averaged velocities of beam footprint and satellite, mainly depending on the inclination, eccentricity, and look angle.