基于北斗GEO卫星和IGSO卫星的地基双站SAR关键算法研究

The bistatic SAR, which uses the satellites of the Global Navigation Satellite System as transmitters, is a novel tool for the earth observation. With this new configuration, the multi-perspective scattering information of the target can be acquired. Furthermore, the electromagnetic stealth also can be achieved when this system is used for reconnoitering the enemy area. Hence, it can be widely applied in the military and civil fields. In this program, the key algorithms of the ground-based bistatic SAR using the GEO and IGSO satellites of the Beidou navigation satellite system as transmitters is studied. More attention will be paid to the following theoretical contents: the influence of the time and phase synchronization error, the signal sidelobe, and the system interfering signals on the imaging results will be analyzed; the accurate approximation made to the range and Doppler phase histories and the achievement of expressions of the two-dimension frequency spectrum for the point target will be studied; the influence of the residual RCM and the residual phase produced in the azimuth compression on the imaging quality will be analyzed. In addition, the real experiments will be conducted with the existing experimental instruments, and the practical application effect of the proposed algorithms and the imaging performance of the proposed systems will be investigated. With the success implementation of this program, potential of the Beidou navigation satellite system for being applied in the passive bistatic SAR will be further tapped, and the application area of the Beidou navigation satellite system can be expanded. Moreover, a very good tool for permanent monitoring of the important targets will be provided.

基于全球导航卫星系统卫星的双站SAR作为一种全新的对地观测手段，能获取目标多视角散射信息和实现对敌侦察时的电磁隐蔽性，在军事和民用领域中有着广阔的应用前景。本课题开展以北斗GEO卫星和IGSO卫星作为发射源的地基双站SAR关键算法研究。着重分析时间和相位同步误差、信号旁瓣和系统干扰对成像结果的影响，研究距离历程和多普勒相位历程的准确近似、点目标二维频谱表达式的获取，分析残留距离徙动和方位压缩中的残留相位对成像效果的影响。同时，利用已有实验平台开展实际观测实验，分析算法的实际应用效果和考察系统的实际成像性能。本课题的实施将进一步挖掘北斗卫星在无源双站SAR中的应用潜力，有利于拓展北斗的应用范围，而且也可为连续监测关键目标提供一种很好的手段，具有重要的科学意义和现实意义。

基于全球导航卫星系统卫星的BiSAR作为一种全新的对地观测手段，能获取目标多视角散射信息和实现对敌侦察时的电磁隐蔽性，在军事和民用领域中有着广阔的应用前景。本项目分析了北斗卫星各频段信号特性、卫星运动轨迹和可视时间；针对接收天线由移动载体搭载和接收天线固定于地面这两种情况，给出了BiSAR选择北斗卫星作为发射源时所能获得的SNR和空间分辨率，并且与其它导航卫星作为发射源时的系统性能进行了对比分析，从理论上充分论证了以北斗卫星作为发射源的BiSAR能获得的性能参数。这些研究成果可为以导航卫星作为发射源的其它无源雷达性能参数分析提供理论借鉴；依据以北斗GEO卫星和IGSO卫星作为发射源的地基BiSAR系统几何结构，建立了信号旁瓣抑制方法以及系统中存在的各种干扰信号的抑制算法。同时提出了基于照射卫星直射信号实现系统时间频率同步的方法，为系统建立了合适的预处理算法；建立了系统回波信号的精确表达式和点目标二维频谱表达式的获取方法，并为以北斗GEO卫星或IGSO卫星作为发射源而且接收天线由移动载体搭载的地基BiSAR建立了改进型距离–多普勒成像算法，为以北斗IGSO卫星作为发射源而且接收天线固定于地面的长合成孔径时间地基BiSAR建立了后向–投影成像算法；研制了一套更适合于开展基于北斗GEO卫星和IGSO卫星的地基BiSAR成像实验的多通道接收设备，并通过实际实验验证了所建立的信号处理算法的有效性，完成了基于北斗GEO卫星和IGSO卫星的地基BiSAR对地物目标进行实际成像的性能评估。这些研究成果有望为连续监测随时间快速变化的目标和军事敏感目标提供一种很好的手段，而且可充分挖掘北斗卫星在无源BiSAR中的应用潜力，有利于拓展我国北斗卫星的应用范围。此外，研究成果也可为其它类型BiSAR成像算法的研究积累技术。项目组忠实执行了研究计划，完成了规定的研究内容，发表学术论文5篇，参加国际国内会议5人次，申请发明专利2项，培养博士后2名，博士硕士研究生5名，达到了预定的研究目标。