An improved motion compensation method for high resolution UAV SAR imaging

The polynomial and sinusoidal motion errors always exist in the unmanned aero vehicle (UAV) SAR due to the small size and low velocity of the platform, causing serious spectrum compressing/stretching and significant spectral replicas of the azimuth signal. The motion errors induce serious blurring of the SAR image and "ghost targets", and can hardly be precisely estimated by the conventional motion compensation (MOCO) method. In this paper, an improved MOCO method is proposed to estimate and eliminate the motion errors in the high resolution UAV SAR without high precision inertial navigation system (INS) data. The time domain range walk correction (RWC) operation in the coarse phase error estimation process of the proposed MOCO method is the key operation that ensures the estimation accuracy of the whole MOCO method. Finally, the validity of the improved MOCO method is verified by computer simulations and real UAV SAR data processing.