2-12
IM AQ1210-01EN
Backscatter Level
Light that travels through an optical fiber cable displays a phenomenon known as Rayleigh scattering.
Due to this phenomenon, light is sent backwards, in the direction opposite to the direction of
propagation. This phenomenon is known as backscattering. The backscatter level setting is used when
the instrument calculates the return loss and total return loss.
If you do not set the correct backscatter level, the return loss and total return loss measurements will
be incorrect.
On the instrument, you can select the reference pulse width for the backscatter level (see section 3.2).
The selectable range of backscatter levels vary depending on the reference pulse width.
1µs:Therangeis–10.00to‒64.99.
1ns:Therangeis–40.00to‒94.99.
The instrument has the following preset backscatter levels that correspond to each wavelength.
Wavelength 1 µs pulse width 1 ns pulse width
1310 nm –50dB –80dB
1550 nm –52dB –82dB
1625 nm –53dB –83dB
1650 nm –53dB –83dB
Index of Refraction (IOR)
The instrument uses the index of refraction to calculate the distance. If you do not set the index
of refraction correctly, the distance measurement will be incorrect. The index of refraction varies
depending on the connected optical fiber cable. Enter the value recommended by the manufacture of
the cable.
The instrument has the following preset indices of refraction that correspond to each wavelength.
Wavelength Index of Refraction (IOR)
1310 nm 1.46000
1550 nm 1.46000
1625 nm 1.46000
1650 nm 1.46000
You can specify a value from 1.30000 to 1.79999.
2.2 Analysis (Analysis) Conditions
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