基于机会照射源的无源雷达动目标成像方法研究

发布时间：2018-03-11 06:12

  本文选题：无源雷达　切入点：机会照射源　出处：《南京航空航天大学》2014年硕士论文　论文类型：学位论文

【摘要】：无源雷达是一种自身不发射电磁信号的雷达,它利用各种外部辐射源实现对目标的无源检测与成像,因此具有良好的电子对抗特性。随着科技的不断发展,近些年可用外部机会照射源的数量日益增多,分布更加广泛,由于不仅可获得良好的电子对抗特性,还可节省系统成本和节约频带资源,基于机会照射源的无源雷达再次成为研究热点。另一方面,动目标是一类非常重要的雷达目标,针对动目标的探测与成像技术一直以来是雷达领域的重要研究内容。基于上述两方面,论文开展利用WiMAX、WiFi等外部机会照射源的无源雷达动目标成像方法研究。首先简要介绍无源雷达的概念及其成像技术,回顾国内外相关研究现状,并给出本文的研究背景、意义及主要内容。然后开展利用机会照射源的无源逆合成孔径雷达(ISAR)成像技术研究。ISAR是一种用于非合作运动目标成像的雷达,可获得动目标的高分辨图像,用于雷达目标识别。基于机会照射源的ISAR成像属于双基ISAR成像,论文首先阐述双基ISAR成像原理,以及必需的ISAR运动补偿和成像方法,然后以复杂海情下舰船目标成像为例,采用WiMAX信号,给出具体的无源舰船成像方法和成像处理流程,最后利用WiMAX信号对无源ISAR成像性能进行验证。目前大部分已有无源成像方法假定发射源信息已知或是通过辅助手段获取,然后经过最佳匹配接收处理,然而发射信号的信息通常很难获得,且会增加系统的硬件成本。论文给出一种无需发射源信息的无源成像方法。该方法基于广义似然比检验理论,且适用于合作与非合作运动目标成像。通过分析该成像方法的点目标扩展函数,对动目标成像分辨率进行分析,并在此基础上研究不同接收机和发射源配置对成像的影响。在自由空间的基础上,进一步研究多径环境下的无源动目标成像。以往处理中,大多数算法均是直接将多径信号抑制,未将其考虑到成像中。通过建立符合多径环境下的回波模型,将多径分量引入到成像中,研究其对成像可能存在的积极与消极作用。由于大部分机会照射源带宽窄,导致成像距离向分辨较差,针对这一现状,论文研究利用多通道合成技术以改善系统的距离向分辨。首先建立多通道信号模型,推导多通道带宽合成处理方法,然后以多通道DVB-T信号为例,给出模糊函数特性分析并进行仿真实验。结果表明成像的距离分辨率得到提高,验证了该处理技术的有效性。论文最后对全文所做工作进行总结,指出仍需进一步研究的问题。
[Abstract]:Passive radar is a kind of radar which does not transmit electromagnetic signal by itself. It uses various external emitter sources to realize passive detection and imaging of target, so it has good characteristics of electronic countermeasure. With the development of science and technology, In recent years, the number and distribution of sources of exposure to external opportunities available are increasing and more widely distributed, as a result of which good electronic countermeasures characteristics can be obtained, as well as system cost savings and frequency band resources savings, Passive radar based on opportunistic irradiating source has become a research hotspot again. On the other hand, moving target is a kind of very important radar target. Detection and imaging technology for moving targets has been an important research content in radar field. Based on the above two aspects, In this paper, the imaging method of passive radar moving target using external opportunity sources such as WiMAXY WiFi is studied. Firstly, the concept and imaging technology of passive radar are briefly introduced, and the research status at home and abroad is reviewed, and the research background of this paper is given. Research on passive inverse synthetic Aperture Radar (ISAR) Imaging using opportunistic irradiating sources. ISAR is a kind of radar used for imaging non-cooperative moving targets, which can obtain high resolution images of moving targets. For radar target recognition, ISAR imaging based on opportunity source is bistatic ISAR imaging. The principle of bistatic ISAR imaging, the necessary ISAR motion compensation and imaging methods are described in this paper, and then the ship target imaging under complex sea conditions is taken as an example. Using WiMAX signal, the specific imaging method and processing flow of passive ship are given. At last, the passive ISAR imaging performance is verified by WiMAX signal. At present, most of the existing passive imaging methods assume that the source information is known or obtained by auxiliary means, and then receive the best matching processing. However, the information of transmitted signals is usually difficult to obtain and increases the hardware cost of the system. In this paper, a passive imaging method without transmitting source information is presented. The method is based on the generalized likelihood ratio test theory. And it is suitable for cooperative and non-cooperative moving target imaging. The resolution of moving target imaging is analyzed by analyzing the point target expansion function of the imaging method. On this basis, the influence of different receiver and source configuration on imaging is studied. On the basis of free space, the passive target imaging in multipath environment is further studied. Most of the algorithms directly suppress the multipath signal and do not take it into account. By establishing the echo model in a multipath environment, the multipath component is introduced into the imaging system. To study its possible positive and negative effects on imaging. Because of the narrow width of the source band due to most opportunities, the range resolution of the imaging is poor, and in view of this situation, In this paper, the multi-channel synthesis technology is used to improve the range resolution of the system. Firstly, the multi-channel signal model is established, and the processing method of multi-channel bandwidth synthesis is derived, and then the multi-channel DVB-T signal is taken as an example. The characteristics of the ambiguity function are analyzed and simulated. The results show that the range resolution of the imaging is improved, and the effectiveness of the processing technique is verified. Finally, the paper summarizes the work done in this paper, and points out the problems that need further study.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN958.97
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本文编号：1596912