An OTDR is not as accurate as the optical attenuation test set for measuring loss.

• A. Is
• B. Depends On Fiber Length
• C. Is Not
• D. Always Equal To

Answer: (C)

Measuring end-to-end optical loss with a tool relies on how the measurement is made. An OTDR estimates loss by sending a pulse into the fiber and analyzing the backscattered light to infer attenuation along the link. That deduction is influenced by backscatter levels, distance, event dead zones, connector and splice reflections, launch conditions, and the instrument’s calibration and dynamic range. Because of those factors, the end-to-end loss value from an OTDR is typically less precise and less traceable than a direct loss measurement.

An optical attenuation test set, on the other hand, uses a known reference path with a calibrated light source and a power meter to compare transmitted and received power, yielding a direct, traceable end-to-end loss measurement with tighter tolerances. So, the statement is true: the OTDR is not as accurate as the optical attenuation test set for measuring loss. Use the OTDR to locate faults and estimate per-event loss, and rely on the attenuation test set for precise total loss.