【作者】 聂丹；

【导师】 郭桂蓉；

【作者基本信息】 国防科学技术大学 ， 信息与通信工程， 2008， 硕士

【摘要】 脉冲合成高分辨体制雷达以其距离分辨力高、系统复杂性低、成本低、易于工程实现等优点而受到人们的广泛关注。本论文研究了以频率步进信号为工作波形的脉冲频率步进雷达的速度估计与距离像抽取问题,全文工作概括如下:第一章介绍了论文的研究背景和意义,概括了国内外关于速度估计和距离像抽取相关问题的研究历史与现状,并简要说明了论文的组织结构与章节安排。第二章首先介绍了脉冲频率步进信号及其改进信号的波形和数学表达式,这类信号的共同优点是在实现距离高分辨的同时,降低了处理机的接收带宽和实现难度;通过对静止点目标和静止扩展目标成像原理的推导,进一步讨论了过采样条件下的目标成像,指出了在过采样条件下要解决的信息冗余和速度估计问题;最后简要叙述了频域细化等方法对频率步进信号的处理。第三章研究了运动扩展目标的速度估计算法。首先分析了速度对高分辨距离像产生的影响——距离像移位和峰值发散;其次简要总结了现有的速度估计方法,提出了利用频率插值与FFT相结合估计目标速度的新算法,并对现有的正负调频法进行了改进;最后针对扩展目标过采样条件下IFFT后的回波数据矩阵,提出了两种速度估计方法——粗分辨速度估计法和高分辨速度估计法,并对两种方法进行了计算机仿真对比。第四章主要讨论了距离像抽取算法。首先对频率步进雷达系统参数进行了分析,指出在过采样条件下必须采用距离像抽取算法才能获取正确的一维距离像,并讨论了参数的宽紧约束条件对距离像抽取算法的要求;其次,针对静止目标,总结和分析了现有的几种距离像抽取算法的具体实现和抽取性能;最后,针对运动目标,分析了速度对距离像抽取算法产生的影响——假峰问题与散射点遗漏问题。速度的影响可以通过对抽取算法的改进得到解决,本章最后讨论了两种距离像抽取的改进算法。第五章对速度估计问题和距离像抽取问题进行了综合研究。首先简要叙述了频率步进雷达的信号处理流程及其主要信号处理部件。其次提出了两种高分辨距离像的获取方案:第一种为先进行速度补偿后进行距离像抽取的方案;第二种是先进行距离像抽取后进行速度补偿的方案。对两种方案的实现过程分别进行了详细讨论和计算机仿真,并对比分析了两种方案的性能及适用性。两种方案的提出使速度估计问题与距离像抽取问题得到了较好的统一。文末对全文进行了总结,并指出了下一步需要进行的工作和尚待解决的问题。更多还原

【Abstract】 The synthetic high-range-resolution radar has drawn attentions due to its high-range-resolution, low system complexity, low cost and easy implementation. The work of this dissertation is focused on researches of stepped frequency radar including its velocity estimation and profile extraction problems. The main content of this dissertation is summarized as follows:Chapter 1 introduces the research background and the motivation of this dissertation and reviews the previous work including related research history and current status of velocity estimation and profile extraction. The arrangement of this dissertation is briefly introduced at last.Chapter 2 first introduces the waveforms and math expressions of the stepped frequency signal including its improving forms which can reduce bandwidth of the receiver and system complexity. Then, the imaging theories of the stepped frequency radar about both stationary point target and stationary extended target are deduced. Furthermore, the imaging theories in the condition of over-sampling are discussed. At last, some other signal processing methods for stepped frequency signal are introduced.The work of Chapter 3 is focused on the velocity estimation methods for moving targets. Firstly, effect of velocity on the high-range-resolution profile is discussed. Secondly, this chapter summarizes some velocity estimation methods and provokes a new velocity estimation method by using accurate frequency estimation and FFT. Furthermore, improves an already existing velocity estimation method. At last, two velocity abstraction methods are explored by aiming at the extended target.In Chapter 4, the profile extraction methods are analyzed. The system parameters and their effect on profile extraction methods are firstly discussed. By summarizing and contrasting some typical profile extraction methods, the effect of velocity on the extraction methods is revealed. In order to get rid of the effect, the traditional methods need to be improved. Then, two methods are discussed to revise the traditional methods.Chapter 5 mainly works on how to combine the velocity estimation methods and profile extraction methods together in order to get best high-range-resolution profiles. First of all, the signal processing flow and the main parts of the stepped frequency radar are analyzed. Then, two implementations are introduced to combine velocity estimation and profile extraction problems. Finally, the performance of the two implementations are discussed and contrasted.At last, a conclusion of this dissertation is made and some related problems to be solved and some works to be done are pointed out.更多还原