OTR 700 User's Guide Rev02 11/2016
30
Chapter 8 OTDR Operation
Event Analysis Screen
Schematic View
Event Table
Event Map with
adjustable splice
zones
Trace Parameters
Fig 8.10
Sensitivity Settings
There are three levels of sensitivity for the event table and Schematic View. (See Fig 8.4) To change the event
sensitivity, press the Menu button, use the left/right buttons to highlight the settings icon and press select. The
cursor is the yellow highlighted area. (If the yellow cursor is on a value that is the current selection, that block
will be highlighted green.) The setting highlighted in blue is the current setting. Use the LRUD buttons to
highlight the desired setting and press select. To exit the parameter screen, press the menu button.
The lowest setting possible should be used to help filter out any false events that may be caused by short pulse
widths, but are not true perturbations in the optical signal. High sensitivity settings present events with loss
down to approximately 0.1dB, Medium (Md) with events down to approximately 0.2dB and Low (Lo) for events
down to about 0.5dB. Longer pulse widths, and averaging help to lower the number of false events. Highest
sensitivity settings should only be used for traces with high signal level, low noise, long pulse width and long
average.
Macrobend Analysis
Macro bend analysis is performed with the dual trace operation and displayed in the event table. The traces
to be compared must have been performed at the same range and the primary trace must be of the longer
wavelength.
To conduct a macro bend analysis, open the file manager as described in chapter 10. Highlight the first
trace to be loaded (the trace of the longer wavelength) and select to open. Open the file manager again and
highlight the trace to be compared (the trace of the short wavelength), open the drop-down menu under the file
tab and touch dual or use the up or down buttons to highlight dual and press select. Open the event analysis
screen to check for macro bends. If and event on the longer wavelength trace has 0.25db or greater loss than
the same event on the shorter wavelength trace, a macro bend event will be generated on the event table,
identified by a Macro label in the Type column. This event will immediately follow the event it is related to. For
example: If event number one was 5 dB at 1550nm and .5 dB at 1310nm, the second event will be blank for
location, +4.5dB for splice, blank for 2point and DB/KM. The type field will be listed as Macro.
To exit dual trace and macro bend analysis, start a new scan.
