OTDR is an important test equipment used in fiber optic work. During its working process, the optical time domain reflectometer send a series of fiber optic pulses into the fiber cable, the fiber signal light will be scattered back and reflected back because of the fiberglass attribute, fiber joint point or fiber break. The OTDR measure the return pulse and it can detect the fiber optic cable length, fiber optic cable overall attenuation, break pointed.
The Optical Time Domain Reflectometer (OTDR) is useful for testing the integrity of fiber optic cables. It can verify splice loss, measure length and find faults. The OTDR is also commonly used to create a "picture" of fiber optic cable when it is newly installed. Later, comparisons can be made between the original trace and a second trace taken if problems arise. Analyzing the OTDR trace is always made easier by having documentation from the original trace that was created when the cable was installed.
OTDRs are most effective when testing long cables (more than aproximatley 250 meters or 800 feet) or cable plants with splices. The data that the OTDR produces are typically used to create a picture called a "trace" or "signature" that has valuable information for the trained user and can be stored for later reference or to check against a blueprint when network trouble arises. OTDRs should not be used for measuring insertion loss in the fiber optic cable - that task is better left to a fiber optic test source and power meter. OTDRs simply show you where the cables are terminated and confirm the quality of the fibers, connections and splices. Of course, OTDR traces are also used for troubleshooting, since they can show where breaks are in fiber when traces are compared to installation documentation.