OPTICAL-FIBER LINE SURVEILLANCE SYSTEM FOR PREVENTIVE MAINTENANCE BASED ON FIBER STRAIN AND LOSS MONITORING

This paper proposes a surveillance system concept, which includes the analysis of fiber fault factors and monitored items, the architecture for diagnosing fiber degradation and the system configuration. Fiber f aults are classified into two types. One is fiber failure caused by fi ber axial tensile strain and the other is fiber loss increase caused b y fiber bending and the absorption of hydrogen molecules. It was found that there is an urgent need for fiber axial strain monitoring, sensi tive loss monitoring operating at longer wavelengths and water sensing , in order to detect the origin and early indications of these faults before the service is affected. Moreover, an algorithm for predicting and diagnosing fiber faults based on the detected results was investig ated and systematized.