Patent ID: 7995197
Filing Date: 2011-08-09
Classification: G01M,H04B

Abstract:
1. A method of monitoring an optical waveguide to detect a dynamic physical disturbance of the optical waveguide, the method comprising: transmitting pairs of signal copies of a signal output from an optical source onto an optical waveguide including a sensing portion along which a transmitted signal senses a disturbance along the sensing portion, and a return portion, for returning said transmitted signal by a process of distributed backscattering towards the sensing portion; receiving returned backscattered signals generated by the signal copies previously transmitted onto the optical waveguide; for returned backscattered signal components of the signal copies, combining a backscattered component of one signal copy of a pair with the other signal copy of that pair, such that, from the combination of the two backscattered component signal copies of a pair, a combination signal is generated; and generating a disturbance alert signal from the combination signal, wherein the backscattered component signal copies are returned from said return portion by a process of distributed backscattering along the optical waveguide.