提出了一种采用5根光纤纤芯构成的改进型双Mach-Zehnder干涉仪原理的的分布式光纤管道安全预警系统,系统利用管道同沟铺设的通讯光缆,采集管道沿线的微震动信号,系统使用3×3耦合器得到两路相位差信号,解调外界扰动造成的相位变化,得到两个强相关的信号,使用顺反两个方向光信号经过扰动点的时间差定位扰动点的位置,提高了系统的保护距离和定位精度.%A novel distributed optical fiber pipeline security and pre-warning system, which is paved along the pipeline, is proposed. Five fibers in the same cable are used to form a double Mach-Zenhnder Interferometer, which can detect the micro-vibration along the pipeline. In order to gain two correlated signals, two 3×3 couplers are used to demodulate the phase changes caused by perturbation. The location of the perturbation can be measured by the time difference of the two phase signals from both clockwise and counterclockwise lights. The results show that the system protection distance and locating accuracy have been improved greatly.
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