Hardware-In-the-Loop Simulation of Real-Time Precise Orbit Determination for Differential InSAR Satellites Using BDS-3 B1C/B2a Measurements

The high precision orbit and relative baseline determination of Low Earth Orbit (LEO) and its formation satellites are important prerequisites for the differential Interferometric Synthetic Aperture Radar (InSAR) satellite system to complete scientific missions. Currently, the main method to obtain high-precision orbit and baseline products for differential InSAR satellite system is based on Space-Borne GNSS data. In this paper, the Real-Time Precise Orbit Determination (RTPOD) software named SATODS is developed using the method of GNSS-based reduced-dynamic orbit determination, and the software is transplanted into GNSS receivers. Then, the Hardware-In-the-Loop (HIL) simulation system of differential InSAR satellites is built based on a Spirent GSS9000 Multi-GNSS signal simulator and the BeiDou-3 receivers, and the RTPOD using the third-generation BeiDou navigation satellite System (BDS-3) B1C and B2a measurements is processed in the receivers. The HIL simulation results demonstrated that, compared with the simulation reference orbit, the absolute orbit determination accuracies of differential InSAR satellites are basically the same, and 3-Dimensional Root Mean Square error (3DRMS) are better than 0.5 m. The fixed and float solution results for 1 km short baseline are better than 2 mm and 1 cm (3DRMS), respectively. The float solution results for medium-long baseline 50 km and 200 km are better than 2 cm and 4 cm (3DRMS), respectively. The precision of RTPOD using BDS-3 is almost the same as GPS. Therefore, the application of BDS-3 B1C/B2a signals in RTPOD for differential InSAR satellite system is feasible.