Fluke OF-500-01 OptiFiber Technical Reference Handbook page 107

Event
HIDDEN
The event is within the
attenuation deadzone of the
previous event.
GHOST
The event is a duplicate
reflection caused by light
bouncing back and forth
between connectors.
Table 3-4. Event Types (cont.)
The event is detected, but not enough information is available to measure its loss
separately from the previous event. Since the hidden event's loss can't be determined,
it is included with the loss of the previous event. This loss is displayed as "NA".
The hidden event may be a connection, a sharp bend, or a crack within the deadzone
of the previous connection.
If the event is not a connection, inspect the fiber near the event's location. Use a visual
fault locator to reveal faults.
Also see N/A in Table 3-3.
Caused by a dirty or unseated connector, highly-reflective connector, a connector with
the wrong polish, a sharp bend, or a crack in a fiber.
Find the GHOST SOURCE in the event table to determine where to look for the fault.
The ghost source is always before the ghost. The event table does not show ghosts
that occur after the end event.
If the ghost source is a hidden event, the tester may not identify a ghost event as a
ghost.
Looking at OTDR Test Results
Possible Causes and Solutions
3
Using the OTDR
-continued-
3-31