OTDR trace results provide insights into fiber health, identifying faults, splice losses, and reflections. However, interpreting these traces can be challenging without a structured approach. This guide will help fiber optic technicians read and understand OTDR traces accurately. The Optical Time Domain Reflectometer (OTDR) is useful for testing the integrity of fiber optic cables. Testing with. OTDR settings are a balance between dynamic range, acquisition time, spatial resolution and accuracy. By injecting the light from a visible source, such as an LED, la tification or to determine correct connections. This note also provides background information on system link configurations, test equipment and system component considerations that influence.