Viavi 8100 V2 Series User Manual page 323

=> can be used for a first check when expected OSNR <20dB for 10G systems at
channel spacing of 50GHz and higher; and for systems running at 40GBps at
channel spacing of 100GHz or higher
• Medium mode (<5min measurement time)
Polarization nulling will be performed at about 3 times more measurement points
than fast mode
=> to be used when expected OSNR is in the range of 20-25dB for 10G systems
at channel spacing of 50GHz and higher; and for systems running at 40GBps at
channel spacing of 100GHz or higher.
• High mode (<11min measurement time)
Polarization nulling will be performed at about 3 times more points than in
medium mode
=> to be used when expected OSNR is >25dB and for all systems running at 40/
100GBps at channel spacing of 50GHz
Manual Settings: Min Channel Spacing
Min channel spacing needs to be set according to the minimum present channel spacing
in a system.
NOTE
The preset min channel spacing is 50GHz, which works for most of the sys-
tems. For other systems, the operator needs to enter the effective minimum
system channel spacing of the WDM system. This is important for a correct
approximation of the noise distribution inside the transmission band of the
WDM channels.
Example 1: only every second channel is loaded, system looks like 100GHz channel
spacing
User Manual
Chapter 8 Optical Spectrum Measurement
78000010220 Rev. 024
Measurement of I-OSNR
287