超声导波管道缺陷检测的小波阈值去噪法

在超声导波管道缺陷无损检测中，回波信号在接收和处理过程中不可避免地会受到噪声的干扰，另外，超声导波在管道中传播时还存在频散现象，这会给管道缺陷的识别与特征提取带来不利影响。在有限元数值模拟条件下，采用小波分析的方法，利用Daubechies小波家族中的coif3作为小波函数，运用启发式阈值选取方法，对加有噪声的超声导波回波信号进行去噪，实验分析结果表明此方法提高了重构信号的信噪比，有效地抑制了超声导波回波信号中的噪声，在管道缺陷超声导波检测中，可为管道缺陷的识别与特征提取等提供方便。

Ultrasonic guided wave pipeline defect detection using wavelet threshold selection method analysis

In the course of ultrasonic guided wave pipeline non-destructive testing, the echo signal at the receiving and processing will be inevitably affected by noise, in addition, there are dispersion phenomena in existence when ultrasonic guided waves propagate in the pipeline, it would have adverse impact on the pipeline defect＇s identification and feature ex- traction. Under the finite element simulation conditions wavelet analysis method was used, the coif3, belonging to the Daubechies wavelet family, was employed as wavelet function, heuristic threshold selection method was selected, and using above method the ultrasonic guided wave echo signal mixed with noise was denoised, the results show that this method could enhahee the signal to noise ratio（SNR）, the noise in ultrasonic guided wave echo signal could be effectively restrained, in the pipeline ultrasonic guided wave testing, it can provide convenience for pipeline defect＇s identification and feature extraction.