A Novel Sagnac Distributed Optical Fiber Vibration Sensor Based On Time Delay Estimation Algorithm

This paper proposed and demonstrated a novel distributed optical fiber vibration sensor with high sensitivity and high accuracy based on time delay estimation. The light source is divided into two wavelength bands by a wavelength division multiplexer to form two Sagnac interferometers. The dual Sagnac interferometer can detect the interference signals of different bands modulated by the same disturbance, and then obtain the corresponding phase difference by demodulating the interference signals. Based on the time delay estimation algorithm, the phase difference is used to construct two composite signals with time delay, and then the time delay is extracted by cross-correlation to determine the location of vibration. A positioning software is developed based on LabVIEW. Through the vibration simulation experiment driven by piezoelectric transducer (PZT), it is proved that the sensor can realize the disturbance positioning above 400 Hz. The experimental results show that the sensing distance of the sensor can reach 100 km, and the positioning error is within +/- 30 m. It can be widely used in long-distance perimeter security.