Wavelet Thresholding Denoising of Crack Signals using Db12 Basis and SURE Algorithm

After comparing and analyzing the denoising effects of various wavelet thresholding parameters, the final selection is to use the Db12 wavelet basis function for a 3-level wavelet decomposition of the crack signal. The hard thresholding function is applied to filter the wavelet coefficients of the crack signal using the threshold calculated by the SURE algorithm. Finally, the denoised crack signal is obtained by reconstructing the thresholded wavelet coefficients. Taking crack signal 3 as an example, the denoising result using wavelet thresholding is shown in Figure 7.