Patent ID: 7706641
Filing Date: 2010-04-27
Classification: H04B

Abstract:
1. A method for detecting movement of optical fibers of an optical fiber cable comprising: providing a optical fiber cable having a first end and a second end, the cable having a plurality of fibers each of which extends from the first end to the second end; monitoring a plurality of fibers of the cable by detecting movement of the fiber at locations along the length of the fiber by: providing at least one source of light for injection onto the fibers; providing at least one sensor arrangement for receiving light transmitted through the fibers; injecting light from the at least one source into one end of each of the fibers to be monitored; in the at least one sensor arrangement, detecting a series of received light signals which have been transmitted along the fibers to be monitored; in the at least one sensor arrangement, comparing at least some of the received light signals relative to data obtained from previously received ones of the received light signals to detect changes in the received light signals relative to the previously received light signals; in the at least one sensor arrangement, analyzing the changes to determine any changes which are indicative of manipulation of the optical fiber causing movement of a portion thereof along the length thereof; generating an alarm in response to the detection of any such changes which are indicative of manipulation of the optical fiber causing movement of a portion thereof along the length thereof; and using optical communication components to communicate light from the at least one source to more than one of the fibers of the optical fiber cable and to communicate light from more than one of the fibers of the optical fiber cable to the at least one sensor arrangement such that the number of fibers of the optical fiber cable monitored is greater than the number of sources and greater than the number of sensor arrangements.