Positioning method for phase-sensitive optical time-domain reflectometry optical fiber sensing system

Abstract

The invention relates to a phase sensitive optical time domain reflection fiber sensing system positioning method, which comprises the steps of collecting beat frequency data signals corresponding to multitime light pulses; obtaining a backward diffusion light phase matrix phi; determining an extraneous vibration disturbance position Y; selecting a position X1, a position Z1, a position X2 and a position Z2 that have no phase disturbance before and after the extraneous vibration disturbance position Y; phase unwrapping the X1, Z1, X2 and Z2 at the corresponding column phase in the backward diffusion light phase matrix phi; and then expanding the phase change to a scope of -infinity to +infinity. If the phase of the position is the same while time passing by before and after the phase disturbance position, the phase disturbance is determined to be a false alarm; otherwise, the phase disturbance is determined to be a real extraneous vibration event. The problem of introducing a fault abnormal phase because of polarization fading or interference fading in a phi-OTDR system application is solved; a high rate of false alarm because of fading is reduced; and an accurate positioning of a real extraneous disturbance event is realized. The method is simple and practical in a normal phi-OTDR fiber distributed sensing system.

Description

technical field [0001] The invention relates to a positioning method for a phase optical fiber sensing system, in particular to a positioning method for a phase-sensitive optical time domain reflection optical fiber sensing system, belonging to the field of optical fiber sensing technology applications. Background technique [0002] Phase-sensitive Optical Time Domain Reflectometry (Phase-sensitive Optical Time Domain Reflectometry, abbreviated as Ф-OTDR or Phase-sensitive OTDR) optical fiber distributed sensing system is used to monitor external vibration disturbance events, and can realize the location of external vibration disturbance events It has the advantages of linear distributed measurement, remote measurement, high sensitivity, strong anti-electromagnetic interference, good insulation, intrinsically safe, light weight and small size, and is widely used. In the field of petrochemical industry, Ф-OTDR can realize the monitoring of anti-damage excavation events of oil...

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Problems solved by technology

Rao Yunjiang from Chengdu University of Electronic Science and Technology (Wu Xunwei, Wu Huijuan, Rao Yunjiang, Wu Yu, Zhao Tian, ​​Low false alarm rate distributed fiber optic fence intrusion monitoring system based on comprehensive judgment of multiple wavelet decomposition methods, Acta Photonica Sinica, 2011, 40(11); Distributed optical fiber fence intrusion detection and location method based on Ф-OTDR, Chinese invention patent, inventors: Wu Huijuan, Wu Xunwei, Li Shanshan, Rao Yunjiang, application announcement number: CN 102280001 A) proposed a comprehensive judgment technology using multiple wavelet decomposition methods, passed The difference in wavelet results of different orders can reduce the false alarm rate of fence intrusion. This technology requires complex signal processing algorithms

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