Abstract: Preliminary study for pipeline safety real-time monitoring with distributed fiber optic sensing technique based on coherent Rayleigh backscattering is carried out in this paper. On the basis of a novel one-dimensional impulse-response model of coherent Rayleigh backscattering in fiber, the influence of backscattering power curve with multiple continuous input pulses under external disturbance is explained. Coherent Rayleigh backscattering light power curve is visually presented through numerical simulations with the theoretical model. In order to demonstrate the model, an experimental measurement with 4-km-long single-mode sensing fiber is performed and the position where the disturbance occurs is easily found. To improve the SNR a normalization method of peak-seeking with software is introduced. This method could effectively reduce average number and enhance the maximum detectable frequency range of external disturbance.

Key words: fiber and waveguide optics, distributed optical fiber sensing, coherent Rayleigh scattering, pipeline safety, phase sensitivity