本實驗是使用以自製窄線寬雷射做光源的雙馬赫詹德干涉儀構成光纖入侵感測定位系統，是以人為拍擊光纖感測區域來模擬入侵，並收取干涉入侵訊號來進行定位分析。分析的方式是採用聚類分析演算法的「Hierarchical Clustering」，起初要先設立特徵空間來讓資料點散佈其中，在依照條件分成數個聚類，會先對單張訊號進行第一次分群，其中最大聚類質心為此張定位點，然後以一組多張的方式形成新的資料群進行第二次分群，透過此方式達到兩點入侵定位。經過實驗室的1036公尺光纖光纜的入侵測試，我們驗證了此法能夠準確地找出同時兩點入侵的位置，而準確度達21.55公尺以內。

We use a fiber laser made by our laboratory to be the light source for a dual Mach-Zehnder interferometer aiming to locate two simultaneously occurring intrusion. To simulate the intrusions occurring simultaneously, two people heavily tapped the fiber cable at two different positions in order to produce a clockwise and a counterclockwise detected signals. Then the two signals were loaded into a personal computer through a data acquisition module, and analyzed by software based on the method of hierarchical clustering analysis. In the method of hierarchical clustering analysis, a feature space was created for the data points to be scattered, and then the data points were divided into several clusters according to the conditions required. To locate the two intrusions, the first clustering analysis was performed on the signals detected in a 10 ms time period, with the largest cluster center of mass being the location of the intrusion event. Then, 100 pairs of signals detected sequentially were analyzed to give 100 locations with each specified by a CP value. These 100 locations and their CP values constituted the 100 data points in a feature space for the second hierarchical clustering analysis. By choosing proper cluster numbers in the two clustering analysis, respectively, we could then find the two locations of the two intrusion events. In the test of a 1036 m long fiber cable perimeter, we demonstrated an accuracy to within 21.55 m.

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