Keysight N4917BSCB 400G Optical Receiver Test Application User Guide
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Performing Stressed Receiver Compliance Tests with N4917BSCB Software
5
Figure 27
Placement of RF Attenuator
The flowchart on the following page depicts the N4917BSCB software
stress signal calibration procedure.
NOTE
A Dark Current Calibration triggered without switching off the light at the
optical input port might result in invalid sampling scope calibration. An
error message similar to
11, “Instrument Error; Channel Nx Offset is set
to limit: Entry was out of range"
might be reported.
In this case, navigate to the FlexDCA menu option Tools > Calibrations to
clear and recalibrate the DCA module. Ensure that the optical sampling
scope (DCA) gets recalibrated on a regular basis.
NOTE
Due to the limited output voltage range (75mV to 1V) of the used AWG
modules (M8195A or M8196A) as interference source, the use of an
additional RF attenuator in the interference signal (SI + GN) path is
required in specific hardware configurations. These include the use of
IEEE 802.3cd transmission standards in combination with the new
81492A-E01 reference transmitter or the 81491A-085 multimode
transmitter. In these or other cases, when the N4917BSCB application
aborts the stress signal calibration with an error message indicating that
the AWG voltage has been clipped to its lower range, insert an RF
attenuator (6dB or 10dB) in the interference signal path as shown in
.
