Near-space slow SAR ground moving target detection and imaging

Near-space slow SAR (NSS-SAR) has several advantages such as robust survivability, persistence and flexible maneuvering performance. This paper proposes a NSS-SAR ground moving target detection and imaging method. Since the platform has a slow speed, it is beneficial to separate ground static clutter and ground moving target echo separation. First, Doppler filter is used to separate the spectrum of ground moving target echo from the spectrum of static clutter. After the echo of ground moving target is extracted, first-order Keystone transform and Doppler rate estimation method are combined to accomplish range walk correction and range curvature correction, though motion parameters of ground moving target are unknown. Thus, it provides an approach to solving the difficult problem of correcting range migration of moving target echo. Then, the estimated Doppler rate is used to design azimuth compression function to achieve azimuth focusing. The proposed method is not only suitable for ground slow-moving targets but also fast-moving targets. Computer simulations verify the effectiveness of this method.