29
Abnormal Condition
The situation that there is no reflection peak at the end of a trace shows
above should be paid attention on. If the distance of the tested fiber is
available and the distance shown on OTDR is not equal to the original distance,
this shows that the fiber might be broken down or twisted and the bending
radius of it is over limited. The distance shown on OTDR is the position of the
fault point.
This phenomenon is often used in maintenance. If a fiber is uncertain, we
can bend a fiber and make sure the bending radius is over limited, then use
real time testing function of the OTDR to confirm the fiber.
Distance is Too long
This situation often happened in a long distance testing, caused by
under-range dynamic range of the OTDR that the energy of it can not support
a long distance transmission or caused by a under-range preset testing range
of distance or pulse width corresponding to the actual fiber length.
To avoid this situation, adjust the testing distance and the pulse bigger and
extend the sampling time.
