VeEX OTDR FX150+ Series User Manual page 69

Fiber Properties
• Fiber Model: Select type of fiber to be tested to auto populate Index of Refraction (IoR)
and Backscatter co-efficient (BS) values.
• Wavelength (nm): Select desired wavelength for fiber properties.
• Refractive index N: Setting for each available wavelength (also known as group index)
is used to convert time to distance. Setting proper value (1.2000-1.8000) determines
accurate distance measurement. IoR provided by the cable of fiber manufacturer.
Refractive index can be changed for any stored trace. Enter a custom value or select
fiber type to populate corresponding values.
• Backscattering coefficient, BC: represents level of backscattering in a particular fiber.
It is used for Reflectance and ORL measurement and can be obtained from the fiber
manufacturer. Backscattering coefficient can be changed for any stored trace.
Other Parameters
• Auto Zoom Trace: Use this mode to auto scale the viewing window at the end of the
test.
Note: Disable this feature when using Realtime test mode.
• Front Panel Check: (RxT-4113 only) Report Insertion Loss and Reflectance and advise
if acceptable or not. If testing PON or MUX, use a launch fiber between the OTDR and
Splitter or MUX or disable this feature.
The Fiber/Connection Check is set to OFF by default. Tap the checkbox to disable.
• Front Panel Check: checks the loss and reflectance of the OTDR's connection to the
Fiber-Under-Test or launch fiber. Excessive loss (>1.5dB) or poor reflectance (<-35) will
result in a "Bad connection detected" message. User can stop the test and check the
fiber or resume the measurement.
For OTDR with built-in internal launch fiber, (G.657), the OTDR connector insertion loss
will depend on the fiber type connected to the test set. Mismatched fibers can result in
higher panel loss than expected connector loss. Use the Span button to enter fiber
mismatch compensation. Mismatch fibers should not impact Reflectance.
Span Settings
Press the Span button to configure Span settings.
• Span begin: Enter Length or Index. Used to identify where a launch cable ends and
test fiber begins. Defines the start of analysis by distance or event index. This will
appear as a large green arrow pointing right on screen.
If Event #1 is the end of the launch fiber, set the Span Begin Index to "1".
• Span end: Enter Reverse Length or Reverse Index. Defines the end of analysis by
distance or event index and mark the end of the test fiber. This will appear as a large
green arrow pointing left on screen.
If a launch fiber is used at the far end of the test fiber, set the Span End Index to the
Event # associated to the location where the far end launch fiber starts.
• Include Event Loss: Check to not include connector loss in Total loss summary.
OTDR Series e-Manual, D07-00-076P-RevD00 Page 69 of 109