An OTDR is a powerful tool that helps technicians and engineers assess the health of fiber optic cables. OTDRs inject high-powered light pulses into the fiber using specialized laser diodes. As these light pulses travel down the fiber,. An OTDR is a powerful tool that helps technicians and engineers assess the health of fiber optic cables. OTDRs inject high-powered light pulses into the fiber using specialized laser diodes. As these light pulses travel down the fiber, they encounter various events: connectors, breaks, cracks, splices, and the fiber's end. Such events cause a chang. The primary purpose of an OTDR is to characterize the insertion lossof a link by comparing the difference between the amount of backscatter from the near and far ends. It also measures the amount of light reflected for each event (connectors, splices, etc.), not including the backscatter, relative to the launch pulse. This is called reflectance, ex. Characterizing a fiber link with an OTDR offers several benefits. 1. • A fiber link can contain several connectors and/or splice terminations that may have been performed by different technicians with varying skills. Other disturbances — such as dirty fiber end faces, macrobends, and microbends — can occur within the link due to poor workmanship or. OTDRs are typically available as bench models or handheld devices. Bench-top OTDRs are relatively large, use an AC power source, and have highly specialized functions and features for laboratory testing. In contrast, hand-held OTDRs are smaller, lightweight, and battery-powered for use in the field. Not all hand-held OTDRs are created equal. They h. OTDRs are required for Tier 2 compliance testing within TIA standards and for "extended" testing within ISO standards. They are also ideal for troubleshooting existing fiber cable plants.