Denoising ultrasonic pulse-echo signal using two-dimensional analytic wavelet thresholding
Denoising ultrasonic pulse-echo signal using two-dimensional analytic wavelet thresholding
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DOI：
10.1016/j.measurement.2011.12.007
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发表时间：
2012-04
期刊：
影响因子：
5.6
通讯作者：
Mohammad R. Hoseini;M. Zuo;Xiaodong Wang
中科院分区：
文献类型：
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作者：
Mohammad R. Hoseini;M. Zuo;Xiaodong Wang
当使用超声波角度波束脉冲回波装置时，在接收信号中存在两种噪声：（1）楔形噪声，和（2）随机噪声。在这项研究中，我们提出了一种方法来消除随机和楔形噪声使用二维平稳小波变换（2D SWT）。为了提高二维SWT的性能，我们采用解析小波阈值。这需要计算2D信号的分析信号并提取信号的包络，但是分析信号到多维的规则概括是不可用的。本文证明了在一定条件下，通过引入参考向量，可以准确地提取B超包络。所提出的去噪方法的性能进行评估，使用模拟和实验数据。实验结果表明，我们提出的去噪方法是能够揭示从一个表面破裂裂纹小到0.1毫米的回波。
When an ultrasonic angle-beam pulse-echo setup is used, two kinds of noise are present in the received signal: (1) wedge noise, and (2) random noise. In this study, we propose a method for removing both random and wedge noises using a two-dimensional stationary wavelet transform (2D SWT). To improve the performance of the 2D SWT, we employ analytic wavelet thresholding. This requires calculating the analytic signal for a 2D signal and extracting the envelope of the signal, but no regular generalization of analytic signals to multi dimensions is available. We prove that under some certain conditions, the envelope of the ultrasonic B-scan can be extracted exactly by introducing a reference vector. The performance of the proposed denoising method is assessed using simulated and experimental data. The experimental results show that our proposed denoising method is able to reveal the echoes from a surface breaking crack as small as 0.1mm.