INTRUSION DETECTION TECHNIQUE BY MEANS OF OPTICAL BACKSCATTER PATTERN ANALYSIS FROM FIBER OPTIC MESH

摘要

An intrusion detection technique based on an optical backscatter pattern analysis on a fiber optic mesh is provided to detect intrusion which may cause bend, stretch, distortion, compression as well as simple cut of the fiber optic mesh by comparing the current OTDR(Optical Time Domain Refelectometer) pattern with a pre-defined threshold OTDR pattern and determining whether there is an intrusion or not, thereby providing a more accurate and sensitive intrusion detection system in comparison with a conventional fiber optic mesh guard system which detects cutting only. An intrusion detection technique based on an optical backscatter pattern analysis on a fiber optic mesh includes the following steps of: obtaining a spatial differential pattern of a backscatter ray received from a fiber optic mesh; determining whether the spatial differential pattern is bigger than a predetermined threshold value and determining whether there is disagreement in a peak negatively or positively; and if the previous step is affirmative, alarming by classifying the case into reflective or non-reflective cutting case, detecting the position where an intrusion broke, and determining/alarming abnormal deformation such as bend, stretch, distortion, compression in case of sensing an optical loss increasing position(23) which has optical loss exceeding a predetermined threshold value.