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. This loss can be caused by a multitude of factors, ranging from intrinsic material properties to environmental conditions. Insertion loss testing confirms whether the cable meets design loss budgets. OTDR testing identifies events along the fiber length, including: OTDR is essential for long-distance FTTH feeder and distribution cables. The estimate, called a "loss budget" is calculated using typical component losses for. Fiber optic loss, also known as optical attenuation, refers to the light loss between the transmitter and receiver.
