A method to enhance SNR based on CEEMDAN and the interval thresholding in Φ_OTDR systems.

The present paper proposes a novel denoising method to suppress multi-source noise and enhance the signal-to-noise ratio (SNR) of the phase-sensitive optical-time-domain reflectometer (Ф-OTDR). The method is based on complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) and the interval thresholding. Firstly, the CEEMDAN is applied to the vibration signals to obtain a series of functions called the Intrinsic Mode Functions (IMFs). Secondly, the trip point is determined according to the fact that the product of energy density of the IMF and its corresponding averaged period is a constant. Then, the IMFs of noise dominant mode are treated with interval thresholding, and finally the IMFs and residual are reconstructed to obtain denoised signals. The results show that the SNR of disturbance location increases to 51.21 dB and 52.11 dB respectively, which represents a great improvement when compared with the other two methods. [ABSTRACT FROM AUTHOR]