CALIBRATING A DISTRIBUTED FIBRE OPTIC SENSING SYSTEM

A Method for dynamically calibrating a distributed fibre optic sensing system (100, 200, 300, 400, 500) comprising a light source (101) for generating pulses of coherent light (103), an optical fibre (105) arranged at least partly in a ground soil region (107) to guide the light and a photo detector (109) for detecting scattered light (111) returning from the optical fibre (105) in dependence of time, comprising: obtaining information (117) from which a temporal change of an acoustic transfer characteristic of the ground soil region (107) is derivable; and calibrating the distributed acoustic sensing system (100, 200, 300, 400, 500) based on the changed acoustic transfer characteristic.