SNR Enhancement Method for Φ-OTDR System Based on Sdr SampEn-BiPSO-SVD Algorithm

In order to solve the problem of low signal-to-noise ratio (SNR) of vibration positioning curve in the phase sensitive optical time domain reflectometer (Φ-OTDR), a denoising algorithm based on spatial dependence recurrence sample entropy (Sdr_SampEn) and singular value decomposition (SVD) optimized by improved Particle Swarm Optimization algorithm based on Beer Antennae search (BiPSO) algorithm (Sdr_SampEn-BiPSO-SVD) is proposed. Firstly, the Φ-OTDR system based on heterodyne coherent detection structure is built, and the vibration signal is obtained by I/Q quadrature demodulation algorithm, and the noise source of the vibration signal is analyzed. Secondly, The mathematical principle and denoising process of Sdr_SampEn-BiPSO-SVD algorithm are established. Finally, the noise suppression capability of Sdr_SampEn-BiPSO-SVD algorithm is tested by simulation experiments and Φ-OTDR system experiments, and compared with Wavelet, EMD-PCC, VMD. The experimental results show that the SNR of vibration positioning curves at 1 Hz, 100 Hz, 500 Hz, and 1 kHz improved to 21.28 dB, 29.08 dB, 16.55 dB, and 32.99 dB respectively, and demonstrate the ability to identify multi-point vibration and improve the quality of multi-point vibration positioning signals. And the feasibility and effectiveness of algorithm have been proven in practical application. This algorithm provides a new means for the application of Φ-OTDR system in the field of seismic exploration.