基于小波变换的水下声信号激光干涉探测研究

发布时间：2018-02-08 20:35

本文关键词： 激光干涉探测技术水下声信号小波变换小波脊瞬时频率　出处：《重庆大学》2016年硕士论文　论文类型：学位论文

【摘要】：世界上超过四分之三的国家领土与海洋接壤,同时随着陆地资源的不断开发与利用,很多资源濒临耗竭,因此海洋这个大宝库里丰富的各类资源是世界各国争夺的焦点。海洋无论是在经济上还是军事上都占有举足轻重的地位,人们对海洋的探索活动已经深入一万米以下的海底,因此传统的声呐技术很难满足水下目标探测的要求。如何快速精准的实现水下目标信息的提取是探测水下目标的关键问题。本文研究激光干涉探测技术的基本原理,利用小波变换工具对水表面激光干涉信号进行处理解调出水表面声波的频率和振幅等信息,并设计搭建了一套实验探测系统进行实验研究。相关的研究工作如下:(1)深入研究了水表面声波理论和激光干涉基本原理,推导出水表面质点的运动在理想情况下是一种正弦波运动,同时研究发现当水下产生声源信号时,水下声源的振动会引起水表面质点的振动,且水下声源信号的频率和它引起的水表面微振动波的振动频率是一致的,即水表面散射光和参考光携带了水下声波信息,因此利用此原理提出了水下声信号激光干涉探测的方法,并通过大量的仿真实验验证了该探测方法的正确性。(2)研究提出了一种基于小波变换的水下声信号频率估算方法。介绍了小波变换的基本理论,通过分析光电干涉信号的时频分布特征,发现了小波脊点的分布规律,并根据此规律应用Morlet小波对水下声信号的频率进行估算。设计了利用Mach-Zehnder干涉仪的水表面声波干涉信号解调方法。(3)基于激光干涉原理,搭建实验平台,简要介绍了水下声信号探测系统的水下声信号产生单元、光路设计单元和数据采集单元,通过对水下声信号中低频段和高频段分别进行实验,整个频段实验结果误差都小于0.25%,表明依据小波脊点分布特征的估算水下声信号瞬时频率的方法是行之有效的。综上所述,本文依据水下声信号的小波脊特征,提出水声源信号频率瞬时频率估算的方法,利用该方法进行了探测实验。
[Abstract]:More than 3/4 countries in the world are bordering on the sea, and with the continuous development and utilization of land resources, many resources are on the verge of depletion. Therefore, the rich resources in the great treasure house of the sea are the focus of the world. The ocean occupies a pivotal position both economically and militarily, and people's exploration of the ocean has reached a depth of 10,000 meters below the sea floor. Therefore, the traditional sonar technology is difficult to meet the requirements of underwater target detection. How to extract underwater target information quickly and accurately is the key problem of underwater target detection. The basic principle of laser interference detection technology is studied in this paper. The wavelet transform tool is used to process and demodulate the frequency and amplitude of the surface acoustic wave on the water surface. A set of experimental detection system is designed and built for experimental research. The related research work is as follows: (1) the theory of water surface acoustic wave and the basic principle of laser interference are deeply studied. It is deduced that the motion of water surface particle is a kind of sine wave movement under ideal condition. At the same time, it is found that the vibration of underwater sound source will cause the vibration of water surface particle when underwater sound source signal is produced. And the frequency of underwater sound source signal is consistent with the vibration frequency of water surface micro-vibration wave, that is, water surface scattering light and reference light carry underwater acoustic wave information. Therefore, the method of laser interference detection of underwater acoustic signal is proposed by using this principle. The correctness of the detection method is verified by a large number of simulation experiments. A method of underwater acoustic signal frequency estimation based on wavelet transform is proposed, and the basic theory of wavelet transform is introduced. By analyzing the time-frequency distribution characteristics of photoelectric interference signals, the distribution law of wavelet ridges is found. According to this rule, the frequency of underwater acoustic signal is estimated by using Morlet wavelet. Based on the principle of laser interferometry, an experimental platform is designed based on the demodulation method of water surface acoustic interference signal using Mach-Zehnder interferometer. The underwater acoustic signal generation unit, optical circuit design unit and data acquisition unit of underwater acoustic signal detection system are briefly introduced. The experimental error of the whole frequency band is less than 0.25, which shows that the method of estimating the instantaneous frequency of underwater acoustic signal based on wavelet ridge distribution is effective. In summary, according to the wavelet ridge feature of underwater acoustic signal, A method for estimating the instantaneous frequency of underwater sound source signal is presented and the detection experiment is carried out.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TB56

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