Performing An In-Band Osnr Test In I-Osnr Mode - Viavi 8100 V2 Series User Manual

Chapter 8 Optical Spectrum Measurement
Measurement of I-OSNR
It might be that the system has a visible channel spacing of 100GHz but the min
channel spacing is 50GHz as only every second channel is loaded. This could
also be the case when 50GHz optical interleavers are used to multiplex two
100GHz spaced WDM signals (even and odd channels) together into a 50GHz
spaced system
=> min-ch-spacing needs to be set to 50GHz
Example 2: submarine links
Submarine links often pack 3 channels into the ITU-T 100GHz grid
=> min-channel spacing needs to be set to 33GHz
Manual Settings: OSNR method
The OSNR method can be set according to the application.
• ROADM networks: networks with optical filters in the link:
Set OSNR method to 'filtered' (=pre-set)
In-band noise approximation will be done automatically to match the in-band
noise distribution of the measured filter shape, whatever shape it is: flat top or
rounded
=> set OSNR method to 'filtered'
• Overlapping spectra: systems with Overlapping spectra, having no filter in the
link (e.g. submarine links or 40/100G links at 50GHz channel spacing)
=> set OSNR method to 'unfiltered'
In-band noise will be approximated as a flat distribution.

Performing an in-band OSNR test in I-OSNR mode

In the I-OSNR mode the instrument performs multiple scans for one measurement.
During each scan the polarization controller will change its setting to adopt to the input
signal for a maximum suppression of the signal to get access to the in-band noise.
1 Start the measurement by pushing the S
A green on top of the WDM table will show the progress of the measurement.
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