OTDR (Optical Time Domain Reflectometer) testing measures fiber cable attenuation by sending light pulses down the fiber and analyzing the returning backscatter and reflections. It generates a visual trace (graph) where the slope represents attenuation (loss) per kilometer, helping pinpoint breaks, splices, and faulty connectors.

Standard Fiber Attenuation Limits

Typical signal loss varies by fiber type and operating wavelength. Standard industry limits are as follows:

• Single-Mode Fiber (SMF): Typically ~ 0.35 dB/km at 1310 nm and ~ 0.25 dB/km at 1550 nm.
• Multimode Fiber (MMF): Typically ~ 3.0 dB/km at 850 nm and ~ 1.0 dB/km at 1300 nm.