An Optical Time-Domain Reflectometer (OTDR) is the industry-standard tool for splice loss testing. It works by sending a pulse of light down the fiber and analyzing the backscattered light to create a trace, or signature, of the entire link. Splices appear as distinct “loss events”. To be able to judge whether a fiber optic cable plant is good, one does a insertion loss test with a light source and power meter and compares that to an estimate of what is a reasonable loss for that cable plant. The estimate, called a "loss budget" is calculated using typical component losses for. ic system. Fiber optic testing of a newly installed system not only verifies that the system meets its design requirements, but also creates a performance baseline for all future testing and troubleshooting of t at system.