【作者】 杨凤凤；

【导师】 梁甸农；

【作者基本信息】 国防科学技术大学 ， 信息与通信工程， 2007， 博士

【摘要】 利用星载雷达实现地面运动目标指示(GMTI)功能为地表大面积监视、侦察和目标跟踪、定位提供了可能,具有重要的军事应用价值。利用多通道雷达和分布式雷达的空域采样特征进行GMTI成为目前研究的热点。由于星载雷达GMTI系统是一个涉及领域宽、层次多、高度复杂的大系统,要实现它,在信号处理和系统设计上面临许多挑战,对它开展研究具有十分重要的意义。本文瞄准星载雷达GMTI这一前沿课题,针对GMTI信号建模与仿真、GMTI信号处理、星载分布式SAR-GMTI系统性能分析、星载分布式SAR-GMTI编队优化设计等四个关键技术问题进行了研究,主要工作安排如下:第二章研究了星载雷达GMTI信号建模与仿真。基于小面单元模型和粗糙地面的散射特性,建立了三维场景地杂波模型,推导了地杂波和运动目标的回波信号表达式,分析了动目标的星载合成孔径雷达(SAR)成像特性。给出了回波仿真和GMTI信号处理流程,建成了完整的星载分布式SAR-GMTI仿真系统,为深入研究各种GMTI处理算法和优化系统设计提供了支持。第三章研究了星载雷达GMTI信号处理问题。首先从一般性的收发分置几何关系入手,分析了多通道脉冲—多普勒(PD)体制雷达的地杂波特性,结合具体的双站形式、波束同步方式、地球自转偏航导引、以及天线方向图形式,给出了杂波秩预测实例。采用非平稳杂波抑制算法与固定结构降维算法级联的形式提高运算效率。然后针对多通道SAR体制雷达GMTI信号处理,研究了两种空时自适应处理(STAP)信号模型的本质区别,揭示了相关脉冲积累时间(CPI)的长度对杂波秩和目标功率谱的影响。最后针对星载分布式SAR-GMTI系统,对比研究了顺轨干涉(ATI)、图像域自适应滤波等算法,修正了ATI方法,分析了现有的两种图像域自适应滤波方法的本质,比较说明了各种算法的适用性。第四章分析了星载分布式SAR-GMTI系统检测性能。与以往只分析干涉相位误差的研究思路不同,本章通过揭示各因素与SAR图像相关系数的关系,从本质上分析了时间、频率同步误差以及热噪声、基线、图像配准误差等参数对星载分布式SAR-GMTI处理性能的影响,比较了分布式GMTI系统和分布式InSAR系统对各参数指标的要求,为星载分布式SAR-GMTI系统设计提供了理论指导。第五章研究星载分布式SAR-GMTI编队优化设计。在信号处理和检测性能分析的基础上,提出了一种测速比和时间效用比的联合指标,作为衡量编队系统整体GMTI能力的标准,比较了Cartwheel、Pendulum、SAR-Train等典型编队的GMTI性能。针对沿航向编队,提出基于信号正交原理优化基线配置的方法,性能较均匀线阵和最小冗余阵有一定程度提高。针对立体编队,抽象出了优化目标的数学模型,结合雷达信号检测要求和编队卫星轨道控制知识确定了搜索空间的范围,采用遗传算法搜索得到了一个3星优化编队。更多还原

【Abstract】 Ground Moving Target Indication(GMTI) using Spacebome Radar(SBR) gives the opportunity for large scale surveillance,spying,and target tracking,position.It is specially valuable for military application.Utilizing the space domain sampling character of multi-channel radar and distributed radar for GMTI is attractive to researchers.Since SBR GMTI system is a multilevel and complex large-scale system concerning broad technology,many challenges about signal processing and system design will be encountered.It is significant and valuable to study it.With the spaceborne GMTI radar as the background,this dissertation focuses on four crucial techniques:the GMTI signal modeling & simulation,GMTI signal processing,distributed SAR-GMTI system performance analysis,distributed SAR-GMTI optimum formation design.In the second chapter,SBR GMTI signal modeling & simulation are researched. Based on the small facet model and the scatter characteristic of the rough terrain,3-D ground scene clutter model is established.The received signal expression of clutter and moving target are formulated.The moving target imaging character is tested.The simulation method of receive signal and GMTI procession flow are discussed comprehensively,and an integrated distributed spaceborne SAR-GMTI simulation software is established.The software will be usefull for the deeper research in GMTI procession algorithms and optimum system design.In the third chapter,SBR GMTI signal processing algorithms for Short coherent pulses integrated(CPI) multi-channel Pulse Doppler(PD) mode,long CPI multichannel SAR imaging mode and distributed SAR-GMTI are researched separately.The ground clutter characteristic of bistatic spaceborne GMTI radar in PD mode is analyzed. The clutter rank is forecasted with considering the bistatic style,beam synchronization, earth rotation,and the directional array pattern.Several nonstationary clutter suppression algorithms dependent on range are researched,and cascade signal processing is used to enhance the efficiency and improve the performance.The natural difference of the STAP signal models for PD and SAR modes is analyzed,and the effects of CPI on clutter statistical character and power spectrum are discovered. Several distributed SAR-GMTI algorithms,such as ATI,two kinds of adaptive filters in image domain,are compared essentially.Proper modification is made to ATI.In the fourth chapter,the detection performance of the distributed spaceborne SAR-GMTI is analyzed.Instead of beginning the research from the phase errors models as the traditional way,we start the research from the more essential matter.A comprehensive expression of the correlation coefficient with time and frequency synchronization errors is given.The influence of synchronization error and some other system parameters are discussed.System parameters requirements for two kinds of interferometric systems,InSAR and GMTI,are compared.This will give powerful theoretical supports for distributed spaceborne SAR-GMTI system design.In the fifth chapter,optimal formation design for SAR-GMTI is studied.Based on the research of signal processing and detection performance analysis,the joint criterion, which combines the detectable velocity percent with the effective system cycle is presented.GMTI performances of some classical formations,such as the Cartwheel, Pendulum,SAR-Train and so on,are evaluated by it.For along-track formation,the optimum baseline configuration is obtained based on the orthogonal signal theory.It has some advantages than Uniform Linear Arrays and Minimum Redundancy Arrays.For 3-D formation,the mathematic model of the optimal object is drawn,and the searching range is established by the requirement for the radar signal detection and the knowledge of the orbit control.As a result,an optimum 3-D formation consisting of 3 small satellites is found through genetic algorithm.更多还原