| 摘要 |
A fibre optic based intrusion sensing system comprises two or more fiber optic cables (111, 112, 113) buried in a shallow trench in the ground, side by side in a predetermined nonzero distance to each other and at one or more predetermined depths. A dynamic distributed fibre optic interrogator measures a predetermined property related to a change in the length of the cables connected to it. A control unit is connected to all interrogators and analyses the measurements of said predetermined property and identifies objects (50) on the surface (20) by combining the simultaneous measurements of all cables and correlating the measurements to the type of object (50) on the ground surface (20), the location of the object on the perimeter, the weight, speed and direction of the object, particularly the direction in (6) or out (5) of the secured perimeter. |
