Tektronix OM4006D, User Manual

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Appendix C: Calibration and adjustment (RT oscilloscope)
9. Once this is done get approximately equal signal on both polarizations
by deleting everything from the Engine Command Window except for
CoreProcessingCommands and adjusting the input polarization as needed.
10. Set the middle slider to achieve minimum signal in the Y-polarization. Since
the input is a single-pol signal at this point, nothing should be in the Y
constellation or eyes except for noise.
11. Display the Y-I or Y-Q eye diagrams and Y-Constellation to see the signal
going into the wrong polarization. This should just be noise when the middle
slider is set properly.
12. The delay calibration is done if there is only noise in eye plots except the X-I
and only noise in the Y-constellation.
13. Click the check box to hide the sliders to avoid accidental change.
14. Save the MATLAB workspace as Delay.mat for later recovery of the delay
data if needed. The delays are now stored in the ChDelay variable.
Figure 15: When adjusting the middle slider, watch the Y-Eye and Y-Const to
minimize the signal in the Y-polarization
Figure 16: Final channel delay values provide only noise in Y polarization
114 OM4000D Series Coherent Lightwave Signal Analyzer