Feature Extraction Based Acoustic Signal Detection in a Cost Effective Φ-OTDR System

The paper presents an experimental demonstration of acoustic signal detection in a phase-optical time domain reflectometer (Φ-OTDR) system based on feature extraction. A commercially available off-the-shelf distributed feedback (DFB) laser is used as a light source with a minimum of 25kHz of linewidth. Also, a low sampling rate (60MS/s) data acquisition (DAQ) system is used to collect the backscattered traces. Using the digital signal processing (DSP) technique, the noisy signal from the Φ-OTDR system is processed to extract the different features of the signal. The location of the acoustic signal source is identified based on variance along the fiber length. Besides, power spectral density at that perturbed location is estimated to determine the acoustic signals frequencies. Using this low cost experimental set-up, the location of the acoustic signal source having 100Hz, 125Hz, and 150Hz frequencies were successfully detected over a 1 km of fiber length.