基于小波奇异性检测技术的海底沉积物声速测量结果分析

Study on the Wavelet Singularity Detection Technique for Sound Velocity Measurement in Marine Sediments

海底沉积物声速是海洋物理学和水声学研究的一个重要物理量。声速测量的准确性取决于如何准确计量超声波在沉积物介质中的传播时间。针对传统的观察波形突变法存在不足,文中基于小波变换独特的时-频局部化特征,阐明了小波变换信号奇异性检测原理,分析讨论如何利用该原理来检测海底沉积物声速测量中的超声回波信号起跳点。用Matlab数值计算软件,把记录的波形数据文件导入工作空间,选用Db3小波进行5层小波分解,观测其模极大值点的位置;用Gauss小波进行连续小波变换,观测其模极大值线的位置。并用两个实例验证了小波变换检测超声回波起跳点可行性及优越性,可提高海底沉积物声速测量的准确性,为海底智能化检测仪器的研发提供技术基础。

The acoustic velocity in marine sediments is one of the most important physical quantities in marine physics and underwater acoustic research. The accuracy of sound velocity measurement depends on the way of accurately measuring the ultrasonic propagation time in sediment medium. In order to overcome the shortcomings of the traditional method for waveform mutation observation, this paper illuminates the principle of wavelet transformation signal singularity detection based on the unique wavelet transformation time-frequency localization characteristics, and analyzes and discusses the way of using this principle to detect the ultrasonic echo signal starting point in sound velocity measurement in marine sediments. The recorded waveform data file is imported into the workspace by using the numerical calculation software Matlab, before choosing Db3 wavelet to conduct 5 layers of wavelet decomposition to observe the position of the maximum point, as well as using Gauss wavelet to do continuous wavelet transformation to observe the location of the maximum line of modulus. With two instances, the feasibility and superiority of utilizing wavelet transformation to detect ultrasonic echo starting point is verified, which can improve the accuracy of sound velocity measurement in marine sediments. This method provides technical support for developing submarine intelligent detecting equipment.