太赫兹雷达目标探测关键技术研究

发布时间：2018-04-15 04:09

  本文选题：太赫兹 + 杂波特性　； 参考：《电子科技大学》2016年博士论文

【摘要】：太赫兹(Terahertz,THz)波在电磁波谱中位于微波频段向光学频段之间的过渡区域。相比于微波频段,太赫兹波具有较短的波长,易实现大时宽带宽积信号和极窄的天线波束;同时,多普勒效应在太赫兹频段更加明显,有利于对运动目标的检测与跟踪。与光学频段相比,太赫兹波对非极性材料具有良好的穿透能力,可以应用于隐蔽目标的探测与成像。以上这些优势使得太赫兹技术在目标探测领域成为研究热点之一,具有重要的研究意义与广阔的应用前景。由于太赫兹波在电磁波谱中的特殊位置,传统的电磁波理论和光学理论都无法准确描述该频段的电磁散射特性,这为利用太赫兹技术进行雷达目标探测带来了困难。相比于微波与光学雷达,关于太赫兹雷达的研究刚刚兴起,特别是由于太赫兹雷达系统关键器件的研制水平相对滞后,直至近几年来才有较为稳定的太赫兹雷达系统样机问世。正是由于上述原因,对太赫兹频段杂波和目标特性的研究一直缺乏实测数据进行分析与验证,这也使得利用太赫兹雷达进行目标检测遇到了一定的困难。本文针对上述问题,在对传统频段雷达杂波与目标特性、检测算法进行总结和分析的基础上,以太赫兹雷达实验为基础,对太赫兹频段目标探测的关键技术进行了一系列的研究。论文的主要工作和贡献包括以下几个方面:1.在总结太赫兹雷达系统进展、传统雷达杂波与目标特性、检测理论和方法的基础上,结合太赫兹雷达的特点,分析了利用太赫兹技术进行雷达目标探测时存在的问题。2.针对太赫兹雷达系统噪声与地杂波统计建模的问题,提出了基于MoLC的太赫兹雷达系统噪声与杂波统计建模方法。该方法结合传统雷达噪声与杂波分布模型,利用MoLC对太赫兹雷达系统噪声与地杂波的统计特性进行参数估计,并通过模型与实测结果之间的KL距离确定噪声与地杂波的统计模型。针对太赫兹频段非均匀地杂波的特点,对其时域与空域特性分别进行了统计建模,验证了太赫兹频段地杂波的统计模型,为太赫兹雷达的应用奠定了基础。3.针对太赫兹频段目标散射波动剧烈的问题,提出了一种基于小角度ISAR成像的太赫兹雷达目标散射特性测量方法。该方法利用太赫兹波长短、ISAR成像所需积累角度小的特点,利用小角度ISAR成像重建目标散射分布图,并从中提取目标各角度的散射特性。实验结果表明,该方法的测量结果可以准确的描述太赫兹频段复杂目标散射的起伏特性与统计特性,解决了传统方法中由于目标回波波动剧烈而导致的测量不准确的问题。4.根据太赫兹宽带雷达目标HRRP特性,提出了使用单一分布模型和混合分布模型对太赫兹宽带雷达目标回波中不同类型距离单元进行统计建模的方法。该方法根据太赫兹雷达目标回波距离单元中散射中心数量与强弱分布的不同对距离单元进行分类,并结合单一分布模型和混合分布模型对不同类型的距离单元回波统计特性进行建模,分别使用MoLC和DSEM对单一分布模型和混合分布模型进行参数估计。实验结果表明,该方法可以对不同分辨率下太赫兹宽带雷达目标的各类距离单元进行统计建模,并取得良好的结果。5.根据太赫兹雷达回波特性,提出了一种基于融合中心的分布式太赫兹雷达CFAR检测算法。该算法利用太赫兹易实现极窄天线波束的特点,设计了均匀分布于圆周上的分布式CFAR检测器,每个局部检测器通过具有极窄波束的天线对观测区域进行扫描,并形成局部二维检测结果,最终,通过融合中心将局部二维检测结果进行融合,得到全局二维检测结果。相比于单一传感器的CFAR检测算法,该算法不仅提高了检测性能,并且能够得到观测场景内各点目标的二维坐标。针对太赫兹高分辨率雷达目标检测的问题,结合太赫兹宽带雷达回波特性,提出了使用基于确定散射中心模型的广义似然比算法对太赫兹雷达距离扩展目标进行检测的思路,并利用实测数据对不同带宽下的检测性能进行了验证与分析,为太赫兹雷达的实际应用提供了技术支持。综上所述,本文围绕太赫兹雷达目标探测关键技术展开了一系列研究,为太赫兹技术的实际应用提供了一定的理论和技术支持。
[Abstract]:Terahertz (Terahertz, THz) wave in the electromagnetic spectrum in the microwave frequency band between the optical transition zone. Compared to the microwave frequency band, THz wave has shorter wavelength, easy implementation of large time bandwidth product signal and antenna beam is very narrow; at the same time, the Doppler effect is more obvious in the terahertz band, is conducive to the detection and the tracking of the moving object. Compared with the optical band, THz wave for non-polar material has good penetrating ability, can be applied to the detection and imaging of concealed targets. These advantages make the target detection in the field of terahertz technology has become a research hotspot, has important research significance and application prospect broad. Because of the special position THz wave in the electromagnetic spectrum, the traditional electromagnetic wave theory and optical theory cannot accurately describe the electromagnetic scattering characteristics of the band, this is for the use of Terahertz Technology Radar target detection difficult. Compared with microwave and optical radar, research on terahertz radar have emerged, especially due to the level of the development of key devices in terahertz radar system is lagging behind, until recent years before the advent of a terahertz radar system like machine more stable. It is because of these reasons, the research on clutter and the target of terahertz has been the lack of measured data was analyzed and verified, which also makes the target detection has encountered certain difficulties using terahertz radar. Aiming at the above problem, in the traditional band radar clutter and target characteristics, based on the analysis and summary of detection algorithm, THz radar experiment based on the key. Terahertz technology of target detection are studied. The main contributions of this thesis include the following aspects: 1. on the basis of Terahertz This progress in radar system, traditional radar clutter and target characteristics, detection theories and methods, combined with the characteristics of terahertz radar, analyzed by using terahertz technology of radar target detection problem when.2. noise in radar system and terahertz clutter statistical modeling, the terahertz radar system and noise MoLC clutter modeling method based on statistics. This method combines traditional radar noise and clutter distribution model, the statistical characteristics of the noise and clutter of the terahertz radar system by using the MoLC parameter estimation, and between the model and the measured results of the KL distance to determine noise and clutter statistical model for terahertz wave. Non uniform ground clutter the characteristics of waves on the temporal and spatial characteristics of statistical modeling, verified the clutter statistical model of THz wave, THz radar should be used for The foundation of.3. to solve the problem of terahertz scattering fluctuations, proposes a measurement method of radar target scattering characteristics of terahertz small angle based on ISAR imaging. The method using terahertz wave length, ISAR imaging features of accumulation of small angle, using small angle ISAR imaging reconstruction of target scattering distribution and extract scattering from the angle of the characteristics of the target. The experimental results show that the measurement results of this method can accurately describe the complex fluctuation characteristics of terahertz frequency and statistical characteristics of target scattering, solve the target to measure wave caused by the severe problem of inaccurate.4. based on terahertz broadband radar target HRRP characteristics due to the traditional method, is put forward methods using a single distribution model and mixed distribution model and statistical modeling of different types of terahertz range unit of wideband radar target echo in the. Method of scattering center based on terahertz radar target echo distance unit number and intensity distribution on different distance unit classification, combined with a single distribution model and mixed distribution model to model the statistical characteristics of different types of echo distance units, respectively using MoLC and DSEM on a single distribution model and mixed distribution model to estimate the parameters. The experimental results show that the this method can, various distance unit of radar target terahertz broadband different resolution for statistical modeling, and achieved good results of.5. according to the echo characteristics of terahertz radar, puts forward a kind of distributed radar CFAR detection algorithm based on terahertz fusion center. The algorithm is easy to realize by using terahertz narrow antenna beam, uniformly distributed CFAR detector distributed in the circumference of the design, each local detector has a very narrow beam through the day Line scanning of the observation area, and the formation of the 2D test results, finally, through the fusion center of local two-dimensional detection results are fused to obtain global two-dimensional detection. CFAR detection algorithm is compared to the single sensor, the algorithm not only improves the detection performance, and can obtain the two-dimensional coordinates of each point in the scene observation target. According to the high resolution radar target terahertz detection problem, combined with the characteristics of terahertz radar echo, and proposes to use the generalized likelihood to determine the scattering center model than the algorithm to detect the terahertz radar range extended target detection based on the idea of the performance of different bandwidth and the measured data were validated and analyzed, which provides technical support for the practical application terahertz radar. In summary, this paper focuses on the key technology of terahertz radar target detection has launched a series of research, It provides some theoretical and technical support for the practical application of terahertz technology.

【学位授予单位】：电子科技大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN957.51
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本文编号：1752444