The OTDR (time-domain optical reflectometer) is a complex yet indispensable tool for many of the activities related to fiber optic networks.
Essentially, an OTDR is a kind of radar that sends out a series of pulses from one side of the network and “listens” to the echo.
On this basis, based on the refractive index of the optical fiber (and therefore the speed of light passing through it), the OTDR is able to construct a map of the network by identifying not only the attenuation and return loss, but also the splice points between the fibers (and the type of splice, fusion or mechanical) and the termination points between connectors, and consequently any faults. Choosing an OTDR can be complex, as these instruments are not particularly cheap.
As always, it's essential to first identify its intended use: single-mode or multimode networks? Should it be used for FTTx networks? What's the maximum network distance to be measured? Is it required for troubleshooting or for overall network certification? We recommend reading some of the short articles listed here or referring to the practical guides on this site.