Crack Signal Denoising: Balancing Noise Reduction and Waveform Preservation

Figure 7(c) provides a visual comparison between the reconstructed signal after thresholding and the original crack signal. The blue waveform represents crack signal 3, while the red waveform depicts the denoised signal. A clear observation from comparing the waveforms before and after denoising is the complete removal of the noise signal. However, the denoising process, while effective, results in a partial loss of the original crack waveform. This loss can be attributed to the threshold value of 0.599 calculated by the SURE algorithm. While this threshold effectively filters out all noise coefficients, it is significantly larger than the crack coefficients in the high-frequency range, leading to the observed waveform loss.