Patent ID: 7564540

Claim:
A fibre optic monitoring system for detecting and locating disturbances along a predetermined length, which comprises: a first fibre optic sensor which extends along said predetermined length and which continuously detects disturbances along the entire predetermined length and produces a first output a second fibre optic sensor which extends along said predetermined length and which produces a second output which detects disturbances and their locations along the predetermined length means for analyzing the output of said first fibre optic sensor to identify disturbances sensed by said first fibre optic sensor which have at least one predetermined characteristic means for analyzing the output of said second fibre optic sensor to determine whether a disturbance was sensed by said second fibre optic sensor at a time approximately corresponding to the time at which the first fibre optic sensor sensed a disturbance with said one predetermined characteristic, and, if so, the location, along said predetermined length, of the disturbance sensed by the second fibre optic sensor.