OTDRs inject high-powered light pulses into the fiber using specialized laser diodes. An Optical Time Domain Reflectometer (OTDR) is the most powerful tool for characterizing fiber optic networks. Proper OTDR usage is. OTDR testing analyzes fiber optic cable performance from end to end by testing components along the cable, including connection points, bends, and splices. This guide dives deep into OTDR technology, its applications, and how it integrates with modern components like optical transceivers. Set core parameters (Wavelength, Distance, Pulse Width); 4. Run the test (Real-time or Average); 5.