The need for testing the performance of fiber optic networks has become essential in today’s world of high-speed communications networks. One of the major faults that can occur in fiber optic networks is a break in the fiber or degraded performance due to use and bending of the fiber, poor connections and Fresnel refractions.
The technique used to detect the location of these faults is optical time domain reflectometry or OTDR. OTDR testing is used to diagnose and locate faults in both LAN networks and long-range fiber runs such as trans-oceanic fibers that are thousands of kilometers long and use repeaters to help carry the signal from the source to the detector. These faults result in reflections of light that degrade the signal being transmitted and even block it completely.
The accuracy of the OTDR device used to test the network is critical to the technicians and engineers in the field. Inaccuracies of the measurement made by the OTDR tester being used will lead to searching for the fault in the wrong place resulting in increased downtime and higher repair cost.
The method used to verify performance of the OTDR consists of utilizing a launch cable of known calibrated length. The accuracy of the time domain reflectometer is determined by sending a pulse thru the launch cable with the device under test and comparing the results of the data gathered by the device under test against the known length of the launch cable. Using this data, Tescom Laboratory Technicians can determine if the DUT complies with the tolerance set by the manufacturer of the OTDR.