摘要
穿墙探测雷达(Through-the-Wall detecting Radar, TWDR)通过发射超宽带(UWB)电磁波来穿透墙壁、隔板等障碍物,并分析接收到的目标回波信号,对隐藏在障碍物后的目标进行检测与定位。
由于墙体的影响,穿墙雷达的动目标检测与定位和常规雷达存在较大差别,针对此问题,本文主要做了以下工作:
1.分析了电磁波对非金属介质墙壁的穿透特性,给出了其对墙体穿透过程中透射系数和反射系数计算方法,建立了穿墙雷达的回波模型并分析了穿墙雷达的步进变频体制;
2.通过分析直达波特性和现有直达波抑制方法的适用性,给出了一种基于极值点定位的步进变频穿墙雷达直达波抑制方法,从而效地抑制了直达波,改方法只能针对步进变频体制;
3.研究了回波信号的时延估计的基本方法,通过分析穿墙雷达回波信号的特点,给出了一种基于小波变换的时延估计方法,可以对回波时延进行有效估计;
4.通过分析电磁波在传播过程中的折射偏移现象以及由此带来的定位误差,给出了基于折射定理的墙体补偿算法和基于不同假定参数的墙体补偿算法,用以校正电磁波折射现象在三圆定位方法中引入的定位误差;
通过仿真与实验结果验证了上述方法的有效性。
By transmiting ultra- wide -band electromagnetic wave which can penetrate the obstacles just like wall, clpboard and so on, Through-the-wall Detecting Radar (TWDR) receives the echo from the targets and analyzes that, then it can detect and locate the objects behind the obstruction.
Because of the obstruction, Through-the-wall Detecting Radar has some differences with general radar in detecting and locating the moving targets, to the problem, the primary researching work of this paper:
1. The characteristic of electromagnetic wave penetrating the medium which is no metal is analyzed and the means to calculate the reflecting and refraction coefficient is given, the model of echo for TWDR is established and the system of TWDR is analyzed;
2. By analyzing the characteristic of the echo arriving straightly and the applicability of the means to reduce it in existence.Given a approach of it’s reduction, it is extremum point localization based on characteristic of step frequency TWDR to reduce the echo effectively;
3. Researching the basic methods of estimating the time delay of echo, an approach based on Wavelet Transform is given by analyzing the characteristic of the echo of TWDR to estimate the time delay of echo availably;
4. By analyzing the refraction phenomena of electromagnetic wave and the error of localization is resulted in this phenomena, an approach based on the refraction theorem and another approach based on different assumed parameters are given to proofread the error in the trilateration scheme by the refraction phenomena;
Using simulation and experimental data we validate the validity of the methods.
引文
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