IMPROVEMENTS IN DISTRIBUTED SENSING

摘要

Techniques for determining lateral offset of the source of an acoustic disturbance in a distributed acoustic fibre optic sensor are described. The sensor comprises an optical source (112) for interrogating an optical fibre (104) and a detector (116) and processor (108) arranged to detect any backscattered radiation and determine a measurement signal for a plurality of discrete longitudinal sensing portions of the optical fibre. The processor is also arranged to analyse the measurement signals to identify signals corresponding to the same acoustic wave arriving at different parts of the fibre and determine from the time of arrival of said acoustic wave the direction and/or distance of the origin of said acoustic wave from the optical fibre. The geometry of the fibre may be arranged to ensure that any positional ambiguity can be resolved and the use of multiple fibres (501, 502) is disclosed.