A high-fidelity numerical model of coherent Φ-OTDR

The existing coherent phase -sensitive optical time -domain reflectometry ( phi -OTDR) model does not systematically consider the impact of various disturbances and noises. More importantly, it cannot effectively simulate low -frequency vibrations. To address this issue, a high-fidelity model is proposed. Unlike the existing models, the proposed model comprehensively considers interference fading, polarization fading, the frequency drift and phase noise of the laser, and the balanced photodetector (BPD) noise, which can effectively simulate the impact of various disturbances and noises on the Rayleigh backscattering (RBS) signals during actual measurement. Quantitative analysis and comparison between the demodulation results of the measured and the numerically generated RBS signals based on the existing and proposed models with 1 kHz, 5 Hz and 1 Hz vibrations show that the proposed model is closer to the experimental system in terms of vibration demodulation results than the existing model.