QQ客服 官方微博 反馈留言

题名	基于脉冲信号的群速、相速估计方法研究
作者	梅璐璐
学位类别	博士
答辩日期	2008-05-23
授予单位	中国科学院声学研究所
授予地点	声学研究所
关键词	瞬态脉冲信号 群延迟 群速度 相速度 简正波 窄带相关 小波变换
其他题名	Research on Group Velocity and Phase Velocity Extraction Based on Instantaneous Impulse Signal
学位专业	信号与信息处理
中文摘要	瞬态脉冲信号是一种很常见的信号，在水声学、超声学、地震学、光学、振动等学科领域中有着广泛的应用，工程上也常用这些信号完成对研究对象的测试，对于这种信号的处理方法一直是研究的热点。由于这种信号具有信息量大、持续时间短等特点，所以用常规的信号处理方法很难取得较好的分析效果。 本文首先对时频分析方法作了一个较为全面的回顾，分析了各种方法的异同，随后，用同一个非平稳信号作为分析对象，对比了几种时频分析方法的处理结果。然后，本文给出了基于线性时变滤波的时频域滤波方法，以及基于尺度的小波域滤波方法，给出了一组参数化高斯窗函数构成的滤波系统的参数选择方案，并给出了对一个多模态信号进行模式分量提取的仿真结果。 之后，本文介绍了海洋中声传播的理论，分析了声信号频散现象的原因，然后介绍了海洋中声信号的群延迟和群速度、相位延迟和相速度的相关理论；在此基础上，提出了以瞬态脉冲信号作为声源，用两个水听器的接收信号，提取海洋声信号群速度和相速度。 在对信号进行群速度提取时，需要首先计算群延迟，于是引出了群延迟与信号包络以及信号重心的关系问题，本文对此进行了研究并提出了一种估计群延迟的建议方法，并以此方法对海洋中脉冲声源激发的信号的群延迟和群速度进行计算，取得了较为精确的计算结果。 目前水声领域直接对信号相速度进行提取的方法很少见诸报道，本文提出了一种窄带相关的方法，用以计算海洋中声信号的相速度，随后的仿真计算也证明了该方法的有效性。 最后，通过对一次海洋声传播实验的数据进行处理，证明了本文提出的方法的可行性，并给出了群速度和相速度的提取结果。
英文摘要	Instantaneous impulses are encountered very often in many applications, such as underwater acoustics research, non-destructive testing, seismic analysis and vibration test. In applications, instantaneous broadband impulse is usually used as an active source. Receivers are used to capture the impulse that has traveled in the medium. The information on the circumstance is carried in the received impulse. Instantaneous broadband impulse analysis has been received a lot of attention during the past twenty years. Time-frequency analysis is the predominant tool to solve this problem. A comprehensive review on time-frequency analysis is presented at the beginning of the paper. In addition, different time-frequency analysis methods are applied on a non-stationary signal and the results are compared. Moreover, a linear time-varying filtering method and a wavelet-based filtering method are proposed. The way of choosing the parameters is discussed subsequently. A method to extract modes from a multi-mode signal based on continuous wavelet transform is presented and simulation results are also given. In chapter 3, acoustic propagation theory in shallow water acoustics is reviewed and the phenomena of dispersion are explained. Theories about group delay and group velocity, phase delay and phase speed of underwater acoustics are also reviewed. Methods for extracting the group velocity and phase velocity of the signal are proposed which take the pulse signal as sound source and based on only two hydrophones. When extracting group velocity of signals, the first step is to estimate the group delay, a question on how to decide accurately the relation of the group delay and the envelope of signal and the gravity of signal is educed. A method that uses the gravity center of the envelope for the estimation is proposed in this paper, it is shown with small error. This method is applied to estimate the group velocity in shallow water acoustic field, and the simulation shows that this method works well. By far, few literatures about phase velocity extraction in underwater acoustics field have been reported. This article presented a method based on correlation of narrow band to calculate the phase speed of sound propagating in ocean and the simulations prove its feasibility. Finally, experimental data got from a sea test are processed to testify the methods proposed and estimation results of group velocity and phase velocity are also given in the paper.
语种	中文
公开日期	2011-05-07
页码	132
内容类型	学位论文
源URL	[http://159.226.59.140/handle/311008/342]
专题	声学研究所_声学所博硕士学位论文_1981-2009博硕士学位论文
推荐引用方式 GB/T 7714	梅璐璐. 基于脉冲信号的群速、相速估计方法研究[D]. 声学研究所. 中国科学院声学研究所. 2008.

个性服务

查看访问统计

相关权益政策

暂无数据

收藏/分享

除非特别说明，本系统中所有内容都受版权保护，并保留所有权利。