Fluke Networks CertiFiber Pro Users Manual - Manual (Page 295)

Chapter 9: How to Use the OptiFiber Pro OTDR Module
Manual OTDR Mode
273
End Threshold
Lets you set the threshold (in decibels) for detection of
the end of the fiber. An event that is above the
threshold is shown as the end of the fiber. The range for
this setting is 1 dB to 25 dB inclusive.
To set the threshold to Auto, tap Auto on the END
THRESHOLD screen.
Loss Threshold
Lets you set the threshold (in decibels) for loss (non-
reflective) events. Events at or above the threshold are
included in the event table. The range for this setting is
0.01 dB to 1.50 dB inclusive.
When you select smaller threshold values (0.01 dB to
0.3 dB), the tester makes a trace with less noise. To do
this, the tester makes more measurements to be
averaged or uses wider pulse widths. Thus, smaller values
can possibly increase test times or dead zones.
Auto sets the threshold to a value based on the selected
test limit, usually 0.10 dB. To set the threshold to Auto,
tap Auto on the LOSS THRESHOLD screen.
Notes
When you set a loss threshold, you cannot be
sure that the tester will find all events that are
at or above the threshold. The characteristics of
the fiber and the use of a manual Averaging
Time or Pulse Width can possibly reduce the
number of events the tester finds.
If you set the loss threshold to less than 0.1 dB,
the tester can possibly find many false events
caused by imperfections in the fiber.
Table 12. Manual OTDR Settings (continued)