超宽带穿墙雷达模拟及目标探测方法研究

发布时间：2018-01-18 11:36

本文关键词：超宽带穿墙雷达模拟及目标探测方法研究　出处：《南京大学》2017年硕士论文　论文类型：学位论文

【摘要】：城市作战、反恐维稳和灾后救援等诸多方面都有着穿透障碍物探测目标的需求。相比其他的穿透探测技术,超宽带穿墙雷达系统具有显著的优势,其工作不受视觉条件、环境变化和天气变化等因素的影响。本文利用电磁仿真算法对超宽带穿墙雷达系统进行了模拟,然后进行了墙后目标探测研究。超宽带穿墙雷达系统的机制主要有冲击脉冲系统、步进频系统、线性调频系统之分,本文研究基于冲击脉冲机制的超宽带穿墙雷达系统。首先介绍了关于穿墙雷达成像的工作原理,建立了墙体数学模型,推导了墙体对于雷达信号的影响。采用窄脉冲超宽带发射信号,给出了雷达回波信号的表达式和回波信号中干扰信号的去除方法。采用时域有限差分法(FDTD)进行电磁仿真。FDTD是一种麦克斯韦方程组的近似解法。文中介绍了 FDTD算法的三个要点:麦克斯韦方程组的差分形式转化,解的稳定性条件,吸收边界条件。以FDTD算法为基础建立了超宽带穿墙雷达系统的电磁仿真模型,给出了仿真模型的相关参数设置方法和信号处理使用的相关软件说明。研究了三角定位和后向投影算法这两种穿墙雷达成像算法。分别研究和比较了雷达发射信号在自由空间、和墙体中的传输过程。根据墙体对算法的影响,在存在墙体的环境下对算法进行了修正。研究了单点和多点静止目标的探测,进行了 MATLAB仿真,给出了成像结果。研究了动目标的探测,进行了仿真,绘制了目标的运动轨迹。进行了超宽带穿墙雷达的生命探测的简单仿真,给出了仿真结果。上述两种成像算法都需要事先已知墙体参数(墙体厚度和墙体的相对介电常数),实际应用时墙体参数往往未知。对于墙体参数未知的情况,提出两种解决方法:一是分析墙体参数对目标位置的影响,根据不同参数下目标的位置的改变生成目标位置变化曲线,求不同配置天线下的曲线的交点;二是根据墙体两面反射信号幅度的变化估计墙体的参数。给出了上述两种方法的估计算法,进行了仿真研究。结果表明,上述两种方法均有效。最后,总结了全文的研究工作,并对下一步的改进和深入研究方向进行了展望。
[Abstract]:Urban operations, anti-terrorist stability, post-disaster rescue and many other aspects have the need to detect targets through obstacles. Compared with other penetration detection technology, UWB wall penetrating radar system has a significant advantage. Its work is not affected by the visual condition, environment change and weather change, etc. In this paper, the ultra-wideband wall-penetrating radar system is simulated by electromagnetic simulation algorithm. The main mechanisms of UWB wall-penetrating radar system are impulse system, step frequency system and linear frequency modulation system. In this paper, the ultra-wideband (UWB) penetrating wall radar system based on impulse mechanism is studied. Firstly, the working principle of penetrating wall radar imaging is introduced, and the wall mathematical model is established. The influence of wall on radar signal is deduced. The narrow-pulse ultra-wideband (UWB) transmission signal is adopted. The expression of radar echo signal and the method of removing interference signal from echo signal are given. Electromagnetic simulation. FDTD is an approximate solution to Maxwell equations. Three key points of FDTD algorithm are introduced: the difference transformation of Maxwell equations. Based on the FDTD algorithm, the electromagnetic simulation model of ultra-wideband wall-penetrating radar system is established. The related parameter setting method of simulation model and the software explanation of signal processing are given. Two imaging algorithms, triangulation and backward projection, are studied, and radar transmitting signals are studied and compared respectively. Sign is in free space. According to the influence of the wall on the algorithm, the algorithm is modified in the environment where the wall exists. The detection of single and multi-point static targets is studied, and the MATLAB simulation is carried out. The imaging results are given, the detection of moving target is studied, the simulation is carried out, the moving track of the target is drawn, and the simple simulation of life detection of UWB wall-penetrating radar is carried out. The simulation results are given. The above two imaging algorithms need to know the wall parameters (the wall thickness and the relative dielectric constant of the wall) in advance. In practical application, the wall parameters are often unknown. For the case where the wall parameters are unknown. Two solutions are proposed: one is to analyze the influence of wall parameters on the position of the target, according to the change of the position of the target under different parameters to generate the curve of the change of the position of the target, and to find the intersection of the curve under the different configuration of antenna; The second is to estimate the parameters of the wall according to the variation of the amplitude of the reflected signal on both sides of the wall. The estimation algorithm of the two methods mentioned above is given and the simulation research is carried out. The results show that the two methods are effective. Finally. The research work of this paper is summarized, and the future improvement and further research direction are prospected.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN958

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