EXFO FTB-700 for FTB-1 - Manual (Page 307)

Description of Event Types
OTDR 299
Positive Event
Positive Event
This event indicates a splice with an apparent gain, due to the junction of
two fiber sections having different fiber backscatter characteristics
(backscatter and backscatter capture coefficients).

A loss value is specified for positive events. The loss specified does not
indicate the true loss of the event.

The true loss has to be measured by performing bidirectional fiber
measurements and bidirectional analysis.
Reflected power
(dB)
Distance
(km)
Positive event