EXFO FastReporter Data Post-Processing Software - Manual (Page 223)

Description of OTDR Event Types
Data Post-Processing Software 217
Reflective Event
Reflective Event
Reflective events appear as spikes in the fiber trace. They are caused by an
abrupt discontinuity in the index of refraction.
³
Reflective events cause a significant portion of the energy initially
launched into the fiber to be reflected back toward the source.
³
Reflective events may indicate the presence of connectors,
mechanical splices, or even poor-quality fusion splices or cracks.
³
Normally, loss and reflectance values are specified for reflective
events.
³
When the reflective spike reaches the maximum level, its top may be
clipped due to the saturation of the detector. As a result, the dead
zone—minimum distance for making a detection or attenuation
measurement between this event and a second nearby—may be
increased.
³
If you set thresholds, the application indicates a reflective fault in the
events table, whenever a value exceeds the reflectance or connector
loss threshold.
Reflected
power (dB)
Distance
(km)
Reflective events
Clipped level