Limitations; Channel Filtering; Field Of Application - Viavi 8100 V2 Series User Manual

Noise power is measured at the center frequency of the switched-off channels.
Noise power is normalized to Noise Acq BW (i.g. 0.1nm) according to the setup param-
eter.
OSNR will be calculated and displayed in the table based on stored P_ch (step 1).

Limitations

The On/Off-OSNR method requires an intervention into the optical system as the optical
channel to be measured needs to be switched-off.
This is only applicable for an out-of-service measurement.
Some ROADM networks contain so called 'self-blocking' ROADMs.
These kind of ROADMs will block all light including the noise, when there is no signal
present (switched-off).
This can be identified when the noise power < -60dBm or an unrealistic high OSNR
value of >35dB is measured.
The self blocking function can be switched off in many ROADMs by the system manage-
ment SW for service activation and trouble shooting purposes.
=> make sure that the self-blocking function is switched of for On/Off-OSNR
measurements.
The On/Off-OSNR application will report OSNR = #### if the measured noise floor <-
60dBm or the OSNR >35dB, as this is normally not present in an optical network when
there are no self-blocking ROADMs implemented.

Channel filtering

Field of application

This option is only available for OSA-501M modules.
It is used to filter out one particular channel and extract it via a port called the "drop port".
User Manual
Chapter 8 Optical Spectrum Measurement
78000010220 Rev. 024
Channel filtering
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