An Advanced Interferometric Baseline Estimation Method (IBEM) for Spaceborne Bistatic SAR

Abstract

Spaceborne bistatic SAR (BiSAR) employs singlepass Cross-Track Interferometry (XTI) to invert Digital Elevation Models (DEMs) of target areas. However, the accuracy of the inverted DEM is affected by various factors, especially interferometric baseline estimation. To this end, this paper proposes an advanced Interferometric Baseline Estimation Method (IBEM) for spaceborne BiSAR. First, the IBEM compensates for the time synchronization deviation of BiSAR systems using the pulse exchange phase synchronization method. Subsequently, the time, position, and velocity vectors of satellites are input into a highprecision orbit propagator to derive the state vectors at the imaging time. Leveraging these state vectors, the interferometric baseline is calculated with the main satellite that transmits radar signals as the origin of the coordinate system. Eventually, interferometric baseline estimation and DEM generation are performed based on two sets of data from the LuTan-1 (LT-1) BiSAR system, and the generated DEMs are compared with the external reference DEM to evaluate the performance of the IBEM and the LT-1 system. Results indicate that the proposed IBEM can accurately estimate the interferometric baseline and has extensive application prospects in future spaceborne multibaseline Interferometric SAR (InSAR) missions.