“…Wang et al used a Savitzky-Golay smoothing filter to remove the random noise higher than 15 Hz and enhanced the pulse waveform [31]. Combining with the method of empirical mode decomposition, Xu et al proposed an adaptive wavelet threshold denoising method and showed that when the SNR was low, the denoising performance of this method was better than the traditional wavelet threshold denoising method [32]. Wang et al proposed a method based on adaptive cascade thresholding to remove the disturbance intervals and showed that an adaptive cascade threshold method could be used to obtain a stable pulse wave [33].…”