OTDR Series e-Manual, D07-00-076P-RevC00 Page 68 of 107
OTDR Setup (Page 1):
Test Parameters (all OTDR models)
• Mode: Manual, Auto, VScout, or VScout Profiles (optional)
• PON Type: Not A PON, Manual PON or Auto PON
• 1st Splitter (manual mode)
• 2nd Splitter
• Distance range (km, m, miles, kilofeet): maximum value of measured distances; the
value of distance range should exceed the expected length of the fiber under test (20%
more). The distance unit type can be set in page 2 of Test Setup.
• Pulse Width, ns: the value of the optical pulse duration; the range of acceptable optical
pulse values depend on the selected distance range and is automatically set by the
OTDR software. Short pulse widths provide better resolution and produce the best
event and attenuation dead zones. Short pulse widths however inject less optical
energy into the Fiber-Under-Test (FUT), resulting in a noisier trace and lower dynamic
range. Longer pulse widths provide the highest dynamic range and are used to test long
fibers.
• Resolution, m: distance between two samples (sampling interval) of the trace; values
depend on the selected distance range. Select smallest value to measure events
spaced close together and use largest value to for longer ranges. Auto mode will deter-
mine best value for Fiber Under Test
• Measurement time, min:sec: determines the duration of measurement process with
averaging. Use Live mode to perform monitoring of the fiber in Real Time. Longer
averaging time improves the SNR and produces a “smoother” trace.
• Optimized For: Select Test Mode: Automatic DR/DZ, maximize dynamic range (DR
mode) or best deadzone, sacrifice range (DZ mode)
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.
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