Implementation Of Underground Optical Fiber Fault Localization Using Multi-point Photodetectors

In modern communication systems the underground optical fiber networks constitute the backbone but they are highly vulnerable to faults which are caused by digging, bending stress, moisture, rodent attacks which are caused by rats, mice, Squirrels, and physical damage.Conventional fault detection modes such as Optical Time Domain Reflectometry (OTDR) require costly equipment and manual work, limiting their suitability for monitoring continuously.This paper presents a low-cost distributed fault localization system using multi-point photodetector nodes deployed along the fiber route.Each node measures local optical power through a tap coupler and transmits data to a central server via an IOT module.A differential attenuation algorithm detects abnormal losses and identifies the fault segment.Experimental results show detection sensitivity of 0.5dB and localization accuracy of 5-20meters depending on mode spacing.The proposed system enables realtime monitoring, cloud-based alerts, and energy-efficient operation suitable for telecom and smart city deployments.