太赫兹雷达微动目标参数估计与成像研究

发布时间：2018-01-06 09:20

本文关键词：太赫兹雷达微动目标参数估计与成像研究　出处：《国防科学技术大学》2014年硕士论文　论文类型：学位论文

【摘要】：太赫兹波通常指频率在0.1THz-10THz之间的电磁波,其频率介于毫米波与红外光之间,处于宏观电子学向微观光子学的过渡频段,在电磁波谱中占有很特殊的位置,具有与其它波段不同的特殊性质。近年来,随着太赫兹源、检测和相关器件的突破,太赫兹雷达技术发展迅速,国内外报道了很多太赫兹雷达系统,主要应用于高分辨成像研究。但是,太赫兹频段目前的研究对象主要是静止目标和转台目标,对太赫兹频段微动目标的研究还很少。而在太赫兹频段,微动表现出了不同于微波段的一些特性,使得微波领域的一些传统方法不再适用。本文深入分析了太赫兹频段微动目标的回波特性及规律,研究了太赫兹频段的微动参数提取算法,探索了太赫兹频段的微动目标识别和高分辨成像方法。第一章系统介绍了课题的背景及研究意义,归纳分析了微动目标微多普勒特征提取、微动目标成像以及太赫兹频段微动研究等方面的主要成果、所采取的技术途径以及目前存在的主要问题,介绍了本文的主要研究工作。第二章提出了一种基于时频拼接的太赫兹微动参数估计算法。首先研究分析了微动目标的雷达回波模型,得出了微动目标回波微多普勒受正弦调制的结论;然后针对太赫兹频段较为显著的微多普勒混叠现象,提出了一种基于时频拼接和逆Radon变换相结合的混叠微动参数估计算法并列出了详细的实现步骤;最后经过实验仿真验证了算法的有效性,分析了算法的估计精度和抗噪性能。第三章提出了一种基于模值Hough变换的太赫兹频段微动参数估计算法。首先分析了第二章算法的适用范围,分析了其在大进动角时不能很好适用的根源;然后提出了滑动散射中心模型,并分析了进动锥体散射中心滑动规律;然后根据这一规律提出了基于模值Hough变换进行参数搜索的算法并列出了详细的实现步骤;最后通过实验仿真验证了算法的有效性和优良性能。第四章研究了几种调频连续波体制的微动目标成像方法。分别分析了太赫兹频段调频连续波转台成像、平动补偿成像和微动角成像等三种传统方式的理论基础,并利用仿真实验和电磁计算数据进行验证,指出了各种算法的优劣及其适用范围。第五章提出了基于稀疏贝叶斯的方位俯仰微动目标成像算法。该算法将压缩感知理论应用于太赫兹频段微动目标高分辨成像,取得了较好的实验结果。首先详细介绍了压缩感知理论,并深入分析了方位俯仰成像的稀疏表示模型。然后通过实验仿真和电磁计算数据验证了算法的性能,得到了较好的微动目标二维像。最后对本文工作进行了整理归纳,总结了本文的主要内容和创新点,探讨了太赫兹频段微动目标研究领域的发展趋势和需要进一步研究的主要问题,明确了今后工作的方向和重点。
[Abstract]:Terahertz wave usually refers to the electromagnetic wave whose frequency is between 0.1THz-10THz, and its frequency is between millimeter wave and infrared light. It is in the transition frequency range from macro electronics to micro photonics. In recent years, with the breakthrough of terahertz source, detection and related devices, terahertz radar technology has developed rapidly. Many terahertz radar systems have been reported at home and abroad, which are mainly used in high-resolution imaging. There is little research on the fretting target in the terahertz band, but in the terahertz band, the fretting shows some characteristics different from the microwave band. Some traditional methods in the field of microwave are no longer applicable. In this paper, the echo characteristics and law of fretting target in terahertz band are deeply analyzed, and the algorithm of fretting parameter extraction in terahertz band is studied. Fretting target recognition and high-resolution imaging methods in terahertz band are explored. Chapter one systematically introduces the background and research significance of the subject and summarizes and analyzes micro-Doppler feature extraction of fretting target. The main achievements of fretting target imaging and the research of fretting in terahertz band, the technical approaches adopted and the main problems existing at present. In chapter 2, a THz fretting parameter estimation algorithm based on time-frequency splicing is proposed. Firstly, the radar echo model of fretting target is studied and analyzed. The conclusion that micro-Doppler echo of fretting target is modulated by sine is obtained. Then, aiming at the obvious phenomenon of micro-Doppler aliasing in terahertz band, an algorithm based on time-frequency splicing and inverse Radon transform is proposed to estimate the parameters of aliasing fretting, and the implementation steps are listed in detail. Finally, the effectiveness of the algorithm is verified by experimental simulation. The estimation accuracy and anti-noise performance of the algorithm are analyzed. In chapter 3, an algorithm for estimating the fretting parameters of terahertz band based on modular Hough transform is proposed. Firstly, the applicability of the algorithm in chapter 2 is analyzed. The root causes which can not be applied well in large precession angle are analyzed. Then the sliding scattering center model is proposed and the sliding law of precession cone scattering center is analyzed. Then, according to this rule, a parameter search algorithm based on modular Hough transform is proposed and the implementation steps are listed in detail. In chapter 4th, the fretting target imaging methods of several FM continuous-wave systems are studied, and the THz frequency-modulated continuous wave turntable imaging is analyzed respectively. The theoretical basis of the three traditional methods of translation compensation imaging and fretting angle imaging is verified by simulation experiment and electromagnetic calculation data. In chapter 5th, we propose an azimuth pitching target imaging algorithm based on sparse Bayesian, which applies the compression sensing theory to the high resolution of the fretting target in terahertz band. Like... Good experimental results are obtained. Firstly, the theory of compression sensing is introduced in detail, and the sparse representation model of azimuth pitch imaging is analyzed in depth. Then, the performance of the algorithm is verified by experimental simulation and electromagnetic calculation data. A better two-dimensional image of fretting target is obtained. Finally, the work of this paper is summarized, and the main contents and innovations of this paper are summarized. This paper discusses the development trend of the research field of THz fretting target and the main problems that need further research, and clarifies the direction and emphasis of the future work.
【学位授予单位】：国防科学技术大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN957.52

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