How will a mechanical splice or a connector show up on the OTDR display?

How will a mechanical splice or a connector show up on the OTDR display?

• A. Fresnal Reflection Spike
• B. Flat line
• C. Random noise
• D. A downward step

Answer: (A)

A sharp Fresnel reflection spike appears at an interface because light encounters an abrupt change in optical impedance when two fibers meet through a connector or a mechanical interface. That boundary between media reflects some of the light back toward the OTDR, creating a bright, narrow spike on the trace. The presence of this spike is the telltale sign of a real boundary between fibers, and its size depends on how well the ends are mated and whether there’s any air gap or imperfect polish. In contrast, a splice without a strong reflection mainly shows up as a small downward step (loss) rather than a spike, a flat line means no event detected, and random noise looks like irregular, low-amplitude fluctuations. So the sharp reflection spike is the best description for how a connector or mechanical interface will typically appear on the OTDR display.

A sharp Fresnel reflection spike appears at an interface because light encounters an abrupt change in optical impedance when two fibers meet through a connector or a mechanical interface. That boundary between media reflects some of the light back toward the OTDR, creating a bright, narrow spike on the trace. The presence of this spike is the telltale sign of a real boundary between fibers, and its size depends on how well the ends are mated and whether there’s any air gap or imperfect polish. In contrast, a splice without a strong reflection mainly shows up as a small downward step (loss) rather than a spike, a flat line means no event detected, and random noise looks like irregular, low-amplitude fluctuations. So the sharp reflection spike is the best description for how a connector or mechanical interface will typically appear on the OTDR display.