A Nonparametric Paired Echo Suppression Method for Helicopter-Borne SAR Imaging

The helicopter-borne synthetic aperture radar (SAR) system suffers high-frequency vibrations caused by the rotor rotation. This micro-vibration induces phase modulation, which gives rise to paired echoes and seriously degrades the quality of SAR images due to the unexpected ghost phenomenon. In this letter, a nonparametric paired echo suppression method for helicopter-borne SAR imaging is proposed. By constructing a modified vibration error model and introducing the autofocus method for the vibration phase error estimation, it can suppress the paired echoes directly, which avoids the complex vibration parameter estimation in the traditional methods. The effectiveness of the proposed method is demonstrated via simulations and real data processing.