A Geometry and Synchronization Error Decoupling and Compensation Approach for Multistatic SAR Imaging

Increasing the synthetic aperture radar (SAR) imaging frame rate is vital for obtaining continuous SAR images and dynamic scene monitoring, which multistatic SAR can achieve. Multiple source synchronization errors in multistatic SAR enable the image to produce positional offset and target defocus, which deteriorate the image quality. In order to obtain highly precise multistatic SAR images, synchronization errors must be compensated for. However, geometry errors are unavoidable during platform movement, which introduce Doppler frequency errors and range cell migration just like synchronization errors. Therefore, these two errors will jointly affect the imaging quality when coupled together, which will increase the difficulty of compensation. Aiming to resolve the issue of obtaining imaging results when the two errors exist simultaneously, this article proposes a decoupled estimation and compensation method for geometry and synchronization error. At first, the coupling relationship between geometry error and synchronization error on echo delay and Doppler frequency is analyzed. Next, the decoupled estimation problem with geometry and synchronization error is transformed into a constrained optimization problem. Then, the differential evolutionary algorithm is employed to address the optimization problem. Finally, the estimated values are utilized to compensate for the echoes to obtain high-resolution imaging results, which are verified by the simulation results. The experimental results convincingly demonstrate the improvement of the proposed method in imaging frame rate and error decoupling ability.