地杂波环境中OFDM雷达目标检测方法研究

发布时间：2018-04-01 21:21

本文选题：OFDM雷达　切入点：目标检测　出处：《国防科学技术大学》2014年硕士论文

【摘要】：地杂波环境中的目标检测一直是雷达领域的研究难点,在实际战场环境中,雷达的检测性能还面临多径、干扰等多种因素的严重制约。作为新的雷达体制,OFDM(Orthogonal Frequency Division Multiplexing)雷达具备多载频、子载波之间相互正交、信号编码方式多样、易于进行波形设计等优势。然而,在不同环境下OFDM雷达目标检测、识别、跟踪等各项性能如何,仍有待深入研究。尤其在地杂波环境中,杂波的幅度分布特性与空间分布特性等,都对OFDM雷达的目标检测性能产生影响。本文立足于此,主要研究了基于似然比检验和基于空时滤波的OFDM雷达目标检测方法。全文主要分为四个部分:第一部分论述了课题的研究背景及意义,并从地杂波环境中雷达目标检测所采用的方法和技术、OFDM雷达关键技术与目标检测方法等方面,阐述了相关问题的研究现状。第二部分着重讨论了地杂波的幅度统计特性与空间分布特性。首先,分析了不同幅度分布的地杂波特性,并仿真产生了相应的杂波信号;然后分析了地杂波的空间分布特性,给出了基于散射单元划分的杂波回波模型及仿真结果。第三部分研究了基于似然比检验的OFDM雷达目标检测方法。首先分析了OFDM雷达信号的基本特性与优缺点;然后,建立了地杂波环境中基于似然比检验的目标检测模型,并采用波形设计方法,改善了雷达的检测性能;最后,仿真分析了OFDM信号峰均功率比约束对检测性能的影响。第四部分研究了基于空时滤波的OFDM雷达目标检测方法。首先分析了地杂波环境下雷达旁瓣对消的性能,发现地杂波的空间分布特性影响了旁瓣对消最优权值的求解,导致对消失效,影响目标检测。为解决此问题,针对OFDM雷达,在机载雷达背景下,建立了OFDM雷达空时自适应处理模型,利用杂波与干扰的空时特性差异实现目标检测。最后,提出了基于多目标优化的波形设计方法,在保证OFDM良好的模糊图特性的同时,提高了雷达空时自适应处理滤波输出,改善了目标检测性能。论文研究的地杂波中的目标检测方法丰富了OFDM雷达相关理论,提出的波形设计方法,有利于改善地杂波环境下OFDM雷达分辨能力与目标检测性能。
[Abstract]:Target detection in ground clutter environment is always the research difficulty in radar field. In the actual battlefield environment, radar detection performance also faces many factors such as multi-path, jamming and other serious constraints.As a new radar system, OFDM orthogonal Frequency Division Multiplexing (OFDM) radar has the advantages of multi-carrier frequency, orthogonal subcarriers, various coding methods and easy waveform design.However, the performance of OFDM radar target detection, recognition and tracking in different environments remains to be further studied.Especially in ground clutter environment, the amplitude distribution and spatial distribution of clutter affect the target detection performance of OFDM radar.Based on this, this paper mainly studies the method of OFDM radar target detection based on likelihood ratio test and space-time filtering.The full text is divided into four parts: the first part discusses the research background and significance of the subject, and from the ground clutter environment radar target detection methods and techniques adopted in OFDM radar key technology and target detection methods, etc.The current situation of research on related problems is described.In the second part, the amplitude statistics and spatial distribution of ground clutter are discussed.Firstly, the characteristics of ground clutter with different amplitude distributions are analyzed, and the corresponding clutter signals are generated by simulation, then the spatial distribution characteristics of ground clutter are analyzed, and the clutter echo model based on the division of scattering units and the simulation results are given.In the third part, the method of OFDM radar target detection based on likelihood ratio test is studied.Firstly, the basic characteristics, advantages and disadvantages of OFDM radar signal are analyzed. Then, the target detection model based on likelihood ratio test in ground clutter environment is established, and the waveform design method is used to improve the radar detection performance.The effect of the PAPR constraint on the detection performance of OFDM signal is simulated and analyzed.In the fourth part, the target detection method of OFDM radar based on space-time filtering is studied.In order to solve this problem, the space-time adaptive processing model of OFDM radar is established under the background of airborne radar, and the target detection is realized by using the difference of space-time characteristic of clutter and jamming.Finally, a waveform design method based on multi-objective optimization is proposed, which not only guarantees the good fuzzy graph characteristics of OFDM, but also improves the filtering output of radar space-time adaptive processing, and improves the performance of target detection.The method of target detection in ground clutter in this paper enriches the theory of OFDM radar. The proposed waveform design method is helpful to improve the resolution ability and target detection performance of OFDM radar in ground clutter environment.
【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】：TN957.51

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