Signal-to-noise ratio enhancement of Φ-OTDR based on Block-matching and 3D filtering

Aiming at successful vibration extraction of Φ-OTDR under the condition of low signal-to-noise ratio (SNR), a differential intensity image denoising scheme based on Block-matching and 3D filtering (BM3D) is proposed. The correlation of data in time domain and space domain was utilized for denoising, which reduces noise significantly while retaining rich details. Distributed vibration sensing with a spatial resolution of 20 m over a 50 km distance was realized in the experiment. The SNR at the end of the optical fiber was increased from close to 0 dB to 37.2 dB.