临近空间慢速平台SAR地面动目标检测与成像

临近空间慢速平台SAR具有生存能力强、持续工作时间长、机动性能好等特点。该文提出了一种临近空间慢速平台SAR地面动目标检测与成像方法。由于平台运动速度较慢,地面静止杂波多普勒展宽较窄,有利于将地面杂波与动目标回波进行分离。首先利用多普勒滤波器实现地面动目标回波与静止杂波的分离,提取出动目标回波;然后将一阶Keystone变换与变分辨多普勒调频率估计方法相结合,在动目标速度未知的情况下完成距离走动校正和距离弯曲校正,解决了动目标回波距离徙动校正难的问题。利用估计出的多普勒调频率设计出方位压缩函数进行方位聚焦,从而完成动目标的检测与成像。该方法不仅适用于地面慢速运动目标,同时也适用于快速运动目标。计算机仿真验证了该方法的有效性。

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.