Denoising algorithm of Φ_OTDR signal based on clear iterative EMD interval-thresholding

Aiming at the problem of low SNR of the phase-sensitive optical-time-domain reflectometer (Φ-OTDR), a novel signal denoising method based on clear iterative EMD interval-thresholding (EMD-CIIT) is proposed. Firstly, the Pearson correlation coefficient (PCC) between intrinsic mode functions (IMFs) and measured signal are calculated so that can determine the trip point between noise dominant mode and signal dominant mode in IMFs. Then, the IMFs with PCC value greater than 0.1 are denoised based on the EMD-CIIT algorithm. Finally, the IMFs and residual are reconstructed to obtain denoised signals. As seen from the knocking and crushing test results, it proves the Signal Noise Ratio (SNR) of signal for the proposed method has been obviously enhanced compared with the wavelet threshold, Wiener filter and spectral subtraction denoising method, which can be raised up to 30.9 dB and 32.82 dB respectively.