EXFO FTB-7000 OTDR Series for FTB-500 - Manual (Page 97)

Testing Fibers in Advanced Mode
OTDR 83
Setting a Default Span Start and Span End
Setting a Default Span Start and Span End
By default, the span start and span end of a fiber are assigned, respectively,
to the first event (the launch level event) and the last event (often a
non-reflective or reflective end event) of a trace.
You can change the default fiber span that will be applied during the initial
trace analysis.
You can even define a fiber span for short fibers by placing the span start
and the span end on the same event.
Changes to the span start and span end will modify the contents of the
events table. The span start becomes event 1 and its distance reference
becomes 0. Only events between the span start and span end will be
numbered in the trace display and Event table. The cumulative loss is
calculated within the defined fiber span only.
Note: You can also change the span start and span end of a specific trace without
changing the default span start or span end (see Analyzing the Fiber on a
Specific Fiber Span on page 172).
To keep the defined fiber span during trace reanalysis, activate the fiber
span delimitation memory (for details, see Saving the Span-Start and
Span-End Information on page 85); otherwise, the span start and span end
markers are reset to zero in the process.