本文選題：探地雷達 + 脈沖合成�。� 參考：《浙江大學》2017年碩士論文

【摘要】：在地質研究領域,探地雷達的應用價值越來越高,例如在地質科研領域;在工程應用中,建筑工程人員利用探地雷達進行地下介質分布情況的探測等。正因為探地雷達應用場景之多,所以對于探地雷達的性能指標的要求也就更加多而復雜。探地雷達發(fā)射高壓脈沖信號,通過接收目標所反射的信號,再進一步對接收信號做分析處理進行二維成像。雷達脈沖能夠探測到的深度與脈沖頻率有關,不同頻段的雷達適應于不同深度的應用場景。而傳統(tǒng)的探地雷達發(fā)射信號頻段單一,無法適應多個應用場景,大大限制了探地雷達的應用價值。所以在考慮如何提高單一探地雷達設備的適應性時,提高探地雷達脈沖發(fā)生器的發(fā)射頻段可調(diào)節(jié)性是一個可行的方案;另一方面,傳統(tǒng)的探地雷達基于若干個反射信號的瞬時振幅生成雷達二維圖像,基于瞬時振幅的二維圖像分辨率低,不利于觀測,而由于電磁波信號在穿越電磁特性差異較大的兩種介質時相位發(fā)生突變,所以我們考慮通過提取雷達反射信號的瞬時相位信息,生成基于瞬時相位雷達二維圖像來解決或改善這一問題;本文首先介紹了探地雷達的發(fā)展歷史和現(xiàn)狀,傳統(tǒng)探地雷達設備應用場景及其優(yōu)缺點,討論了傳統(tǒng)雷達脈沖發(fā)生方法的原理及優(yōu)缺點。由于單個探地雷達裝置通常只能提供一個頻段的雷達脈沖信號,探地雷達可探測的深度與雷達脈沖頻段有關,這使得探地雷達的適應性受到限制,所以本文提出一種基于光誘導開關的通過脈沖合成生產(chǎn)高壓雷達脈沖的方法來設計雷達脈沖發(fā)生器。該方法通過將兩個方向相反的窄脈沖在時域上相加,通過控制兩個脈沖之間的相對時延來改變合成信號的中心頻段。文中詳細介紹了該方法的理論推導和硬件實現(xiàn)方案,并在之后的章節(jié)中進行了仿真進行驗證;探地雷達系統(tǒng)還包括二維圖像生成模塊,用于數(shù)據(jù)可視化以及探測結果顯示。本文介紹了基于瞬時振幅的傳統(tǒng)成像方法,由于該方法成像很多情況下并不能足夠清晰地觀察被探測物,因此本文引入了基于瞬時相位的成像方法。為了提取雷達信號中瞬時相位信息,本文介紹了經(jīng)驗模態(tài)分解及希爾伯特頻譜,介紹了算法原理并分析了其優(yōu)缺點,并提出EMD邊緣效應的優(yōu)化方案。最后進行了相關的仿真實驗驗證,并對實驗結果進行了詳細的分析,最后得出結論。
[Abstract]:In the field of geological research, the application value of ground penetrating radar (GPR) is more and more high, for example, in the field of geological scientific research, in engineering application, GPR is used by construction engineers to detect the distribution of underground media. Because there are many applications of GPR, the requirements of GPR performance are more and more complicated. Ground penetrating radar transmits high voltage pulse signal, and by receiving the signal reflected from target, the received signal is further analyzed and processed for two-dimensional imaging. The depth of radar pulse detection is related to the pulse frequency. However, the traditional ground penetrating radar (GPR) has a single frequency band and can not adapt to multiple application scenarios, which greatly limits the application value of GPR. Therefore, when considering how to improve the adaptability of single ground penetrating radar equipment, it is feasible to improve the tunability of transmitting frequency band of ground penetrating radar pulse generator; on the other hand, Traditional ground penetrating radar generates two-dimensional radar image based on the instantaneous amplitude of several reflected signals, and the resolution of two-dimensional image based on instantaneous amplitude is low, which is not conducive to observation. Because the phase of electromagnetic wave signal is abrupt when it passes through two kinds of medium with great difference in electromagnetic characteristics, we consider extracting the instantaneous phase information of radar reflection signal. This paper first introduces the development history and present situation of GPR, the application scene of traditional GPR equipment and its advantages and disadvantages. The principle, advantages and disadvantages of the traditional radar pulse generation method are discussed. Since a single GPR device usually provides only one band of radar pulse signal, the detectable depth of GPR is related to the radar pulse band, which limits the adaptability of GPR. So this paper presents a method of producing high voltage radar pulse by pulse synthesis based on light induced switch to design radar pulse generator. By adding two narrow pulses in the time domain and controlling the relative delay between the two pulses, the central frequency band of the synthesized signal is changed. In this paper, the theoretical derivation and hardware implementation of the method are introduced in detail, and the simulation results are verified in the following chapters. The GPR system also includes a two-dimensional image generation module for data visualization and the display of detection results. In this paper, the traditional imaging method based on instantaneous amplitude is introduced. Because the imaging method can not clearly observe the detected object in many cases, an imaging method based on instantaneous phase is introduced in this paper. In order to extract instantaneous phase information from radar signal, this paper introduces empirical mode decomposition and Hilbert spectrum, introduces the principle of the algorithm, analyzes its advantages and disadvantages, and puts forward an optimized scheme of EMD edge effect. Finally, the relevant simulation experiments are carried out, and the experimental results are analyzed in detail. Finally, the conclusion is drawn.
【學位授予單位】：浙江大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：P631.3

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