Such as a long distance network or a long campus LAN with splices between cables, you will want an OTDR
to check if the fibers and splices are good. The OTDR can see the splice after it is made and confirm its performance.
It can also find stress problems in the cables caused by improper handling during installation. If you are doing
restoration after a cable cut, the OTDR will help find the location of cut and help confirm the quality of temporary
and permanent splices to restore operation. On singlemode fibers where connector reflections are a concern, the
OTDR will pinpoint bad connectors easily. Since so little of the light comes back to the OTDR for analysis, the OTDR
receiver circuit must be very sensitive. That means that big reflections, which may be one percent of the outgoing
signal, will saturate the receiver, or overload it. Once saturated, the receiver requires some time to recover, and
until it does, the trace is unreliable for measurement .