小波分析在超声信号采集消噪中的应用

Application of wavelet analysis in de-noising of ultrasonic signal acquisition

在使用超声波探伤设备进行探伤过程中,为了抑制噪声信号对缺陷识别和判断带来的影响,采用小波分析的方法,利用Daubechies小波家族的db2做小波函数,借助于小波变换的时-频局部分析特性,对超声波回波信号进行了多分辨率分析.在每一阶设定不同噪声阈值,对输入信号进行噪声去除,并进行信号重建.实验证明,使用该方法能够有效地实现对超声波回波信号的噪声抑制,提高超声波的探伤精度.

Noise signal will affect the identification and discrimination of defects during inspection using ulotrasonic detection equipment.For constraining the influence of noise signal,wavelet transform approach was adopted.The db2,belonging to the Daubechies wavelet family,was employed as wavelet function.Using the time-frequency part analysis characteristic provided by wavelet transform,the multi-resolution analysis of ultrasonic echo signal was performed.The input signal was de-noised by setting different noise threshold in every order,and then the signal was rebuilt.The experiments prove that the noise in ultrasonic echo signal can be effectively restrained and the accuracy of ultrasonic inspection can be improved using the proposed method.