Custom Threshold Denoising for Crack Signal Based on Wavelet Coefficients

The analysis of the cause of crack signal loss reveals that the threshold is too large, and the magnitude of wavelet coefficients varies across different levels. Therefore, it is necessary to design appropriate thresholds for each level of wavelet coefficients. In this section, the SURE algorithm is abandoned, and instead, custom thresholds for each level of wavelet coefficients are used for denoising the crack signal based on their actual magnitudes. The results are shown in Figure 8.