In the hands-on testing, each student should have exercises in all five test methods: microscope inspection of a connector, visual tracing and fault location, optical power measurement, insertion loss testing and OTDR testing. These test procedures assess the physical and functional qualities of fiber optic cables, connectors, and the network as a whole. Why Testing Fiber Optic Cables Matters? Regular testing of fiber optic cables is not just a preventive measure; it's an. This Applications Engineering Note (AEN 135) explains and recommends standard measurement methods for characterizing optical fiber system performance.