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Chapter 12 High Resolution OSA Measurement
DFB results analysis
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' RAODMs.
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.
DFB results analysis
This feature only applies to instruments OSA-50X.
DFB results analysis allows to characterize DFB lasers, by giving the corresponding
SMSR, Offset and bandwidth values.
DFB test configuration
To configure the Platform 8000 in preparation for a DFB test, press the S
402
User Manual
78000010220 Rev. 024
button.
ETUP
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Troubleshooting
