To perform an OTDR test correctly, you must: 1. Set core parameters (Wavelength, Distance, Pulse Width); 4. Run the test (Real-time or Average); 5. This is your "QuickStart" guide to testing fiber optic cable plants with an OTDR. Links to videos and more comprehensive information will be provided in. An Optical Time Domain Reflectometer (OTDR) is the most powerful tool for characterizing fiber optic networks. It is the “doctor” of your fiber network, identifying faults, measuring distance, and evaluating loss. The OTDR works like a radar, sending light pulses and analyzing reflections to show where issues exist. Industry studies show OTDR's advanced dynamic range and spatial resolution make it faster and more.