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超声信号的采集与传输过程中,不可避免会受到大量噪声信号(包括电子噪声和声学噪声)的干扰,对信号进行去噪,提取出原始信号是一个重要的课题因此需要研究比较各种超声信号去噪处理的方法。本文在药柱探伤超声检测信号的去噪方面,对比几种传统去噪方法的优缺点,然后从小波变换的定义和信号与噪声的不同特性出发,分析了小波变换中四种不同的阈值去噪方法。通过理论分析、仿真以及实验研究得出,对于超声回波选取sym8小波基,采用软阈值法,分解层数为3层时,可以有效地去除噪声干扰,突出缺陷信号,去噪性能优于传统去噪方法
During the process of ultrasonic signal acquisition and transmission, it is inevitable that it will be disturbed by a large number of noise signals (including electronic and acoustic noise). It is an important issue to extract the original signal from the signal, so it is necessary to study and compare various ultrasonic signals Denoising method. In this paper, we compare the advantages and disadvantages of several traditional denoising methods in the denoising of the ultrasonic testing signal of the column inspection, and then, based on the definition of wavelet transform and the different characteristics of signal and noise, we analyze four different thresholds in wavelet transform Noise method. Through theoretical analysis, simulation and experimental research, it is concluded that the sym8 wavelet base is selected for ultrasonic echo, and when the decomposition level is 3 layers, the noise threshold can be effectively removed and the defect signal is outstanding. Denoising method