冲激脉冲探地雷达数字采样接收机系统的设计

发布时间：2019-02-14 08:24

【摘要】：探地雷达(Ground Penetrating Radar)是利用高频电磁波来探测目标介质内部物质分布规律的一种地球物理方法。探地雷达具有高效、无损、实时成像等优点,在工程、环境、水文地质调查、考古、军事、生物医疗等领域有广泛的应用。随着探地雷达应用领域的不断拓展,人们对探地雷达技术的要求也越来越高。因此对探地雷达技术的研究具有重要的意义。本文首先对探地雷达的发展历史以及国内外的研究进展情况作了详细的介绍。其次,介绍了探地雷达的基本原理以及现有体制分类,着重介绍了脉冲体制探地雷达的应用与优缺点。再次,介绍了冲激脉冲探地雷达接收机的实现原理以及关键技术。最后,本论文详细介绍了接收机的整体规划设计方案,并对涉及到的电路模块进行了具体的分析与设计,然后对实际电路进行了调试并将实验测得的结果作了介绍。本文主要研究冲激脉冲探地雷达接收机系统的设计。探地雷达接收机是整个系统的核心部件,接收机的性能指标直接影响到整个系统的总体性能。本文设计的接收机由可变增益放大电路、采样保持电路、高精度延时电路、A/D转换电路、FPGA系统控制电路组成。接收机的指标为:工作带宽在0.1 GHz-1 GHz;灵敏度为-76dBm;等效采样率2GS/s;噪声系数小于2dB;采样时窗可达120ns,能够实现对1-5m的地下介质进行探测;目标分辨率在0.2m。为了实现接收机系统的设计要求,本文首先研究了可变增益放大电路的实现,实现了0dB、20dB、40dB的增益可调变化。其次,着重研究了基于等效时间采样原理的采样电路的实现,该部分包含采样保持电路、高精度延时电路、基于SRD的取样脉冲电路的设计等。最后研究了基于FPGA的系统控制电路以及控制程序的实现,完成了利用Altera公司的Cyclone III系列的FPGA芯片实现了对接收机系统的整体控制以及对数字信号的传输处理。最后,对设计的冲激脉冲探地雷达接收机进行的加工调试。然后将整个冲激脉冲探地雷达系统进行了整体测试,特别对设计的探地雷达接收机各部分电路进行了实际测试。从测试的结果可以看出,该接收机能够实现对回波信号的有效采集,整个接收系统工作稳定,设计参数满足指标。
[Abstract]:Ground penetrating radar (Ground Penetrating Radar) is a geophysical method which uses high frequency electromagnetic waves to detect the distribution of matter in target media. Ground penetrating radar (GPR) has been widely used in engineering, environment, hydrogeological survey, archaeology, military, biomedicine and so on because of its advantages of high efficiency, nondestructive and real-time imaging. With the development of ground penetrating radar (GPR) applications, the requirements of GPR technology are becoming higher and higher. Therefore, the study of GPR technology is of great significance. In this paper, the history of GPR and the research progress at home and abroad are introduced in detail. Secondly, the basic principle of GPR and the classification of existing systems are introduced, and the application, advantages and disadvantages of GPR with pulse system are emphatically introduced. Thirdly, the realization principle and key technology of impulse pulse ground penetrating radar receiver are introduced. Finally, this paper introduces the overall planning and design scheme of the receiver in detail, analyzes and designs the circuit modules involved, and then debugs the actual circuit and introduces the experimental results. This paper mainly studies the design of impulse ground penetrating radar receiver system. GPR receiver is the core part of the whole system. The performance of the receiver directly affects the overall performance of the whole system. The receiver is composed of variable gain amplifier circuit, sampling and holding circuit, high precision delay circuit, A / D conversion circuit and FPGA system control circuit. The parameters of the receiver are as follows: the sensitivity of the receiver is -76dBm at 0.1 GHz-1 GHz;, the equivalent sampling rate is 2GS / s, the noise coefficient is less than 2dB, and the sampling window can reach 120ns, which can detect the underground media with 1-5m. The target resolution is 0.2 m. In order to meet the design requirements of the receiver system, this paper first studies the realization of the variable gain amplifier circuit, and realizes the adjustable gain variation of the 0dBU 20dBU 40dB. Secondly, the realization of sampling circuit based on equivalent time sampling principle is studied, which includes sampling and holding circuit, high precision delay circuit, sampling pulse circuit based on SRD and so on. Finally, the system control circuit based on FPGA and the realization of the control program are studied. The whole control of the receiver system and the transmission and processing of the digital signal are realized by using the FPGA chip of Cyclone III series of Altera company. Finally, the design of impulse pulse ground penetrating radar receiver processing debugging. Then the whole impulse pulse ground penetrating radar system is tested, especially the circuit of the designed receiver is tested. From the test results, it can be seen that the receiver can realize the effective acquisition of echo signal, the whole receiving system works stably, and the design parameters meet the requirements.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN957.5

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