ACTIVE CORE DETERMINATION DEVICE

PROBLEM TO BE SOLVED: To provide an active core determination device capable of determining whether an optical fiber core is active or not without influencing communication and regardless of there is a cutoff filter or not and whether a transmission device for a user is on or off.SOLUTION: An active core determination device according to the present invention transmits a determination signal including a wavelength band (for example, 1630 nm or less and 1670 nm or more) passing through a light-shielding filter and a modulation frequency (for example, 270 Hz, 1 kHz or 2 kHz) different from communication light through a determination object optical fiber core toward a user side transmission device direction, and determines whether the core is active or not on the basis of presence or absence of reflection light.SELECTED DRAWING: Figure 1 【課題】通信に影響を与えず遮断フィルタの有無およびユーザ用伝送装置の電源ＯＮ／ＯＦＦにかかわらず光ファイバ心線が現用か非現用かを判別できる現用心線判別装置を提供することを目的とする。【解決手段】本発明に係る現用心線判別装置は、判定対象の光ファイバ心線に遮光フィルタを透過する波長帯（たとえば１６３０ｎｍ以下又は１６７０ｎｍ以上）かつ通信光とは異なる変調周波数（たとえば２７０Ｈｚ，１ｋＨｚまたは２ｋＨｚなど）を有する判定用信号をユーザ側伝送装置方向へ送出し、反射光の有無で現用か非現用かを判別することとした。【選択図】図１