Effective baseline estimation in dual-channel synthetic aperture radar for moving target imaging and relocation

In a dual-channel synthetic aperture radar (SAR) system with the phase centers being positioned along the track, the motion parameters can be obtained by the interferometric phase. When the phase centers of a dual-channel system misalign with the moving track, the interferometric phase depends on the effective baseline length, defined as the projection of the physical baseline on the moving track of the platform. Therefore, the accurate estimation of the effective baseline is crucial for the motion parameter estimation of moving targets in a dual-channel SAR system. This paper proposes a robust model for the estimation of the effective baseline, which considers the motion errors brought by the yaw and rolling of the platform. It also employs an average-median filter to improve the estimated accuracy of the effective baseline in range-compressed domain by considering the error of interferometric phase, such as Taylor approximate expansion, clutter pollution and noise influence. Furthermore, the approach for estimating the along-track and radial velocities of moving targets is presented in detail. The accuracy of the proposed method for effective baseline estimation will be analyzed by the root-mean-square-error (RMSE) compared with the Cramer-Rao bound (CRB). The results by applying the proposed method into a set of real SAR data are consistent with the analysis presented in this paper.