Motion Compensation For Airborne SAR Interferometry

Subject to unstable disturbances, such as atmospheric turbulence, an airborne SAR interferometry (InSAR) platform may deviate from a nominal, straight-line track with its attitude variance. The unstable movements of an airborne InSAR platform lead to defocused radar images and degraded Digital Elevation Model (DEM) accuracy. Therefore, it is necessary to compensate the motion errors. The focus of this dissertation is on analyzing the motion compensation of airborne InSAR using simulation and practical data.In this dissertation, the effects of position and attitude errors on the SAR image quality and DEM accuracy are first analyzed, and then two strategies based on the accurate POS data and the echo data are investigated to compensate the motion errors.For the method based on the POS data, the location and attitude variations are equivalent to the position deviation of the antenna phase centre (APC) from the ideal straight-line track, and then the envelope and the phase are compensated to the ideal reference track, taking account of the effects of the topography, azimuth and range dependence.In practical case, considering the limitation of POS accuracy, the compensation based on the echo data is investigated. The motion parameters can be estimated from the received echo data by using the Doppler parameter estimation techniques, and the motion compensation is then carried out. For the interferometric phase errors caused by the time-varying baseline, two methods based on the registration error and the spectral diversity are investigated to compensate the InSAR motion compensation.