Tektronix OM4006D, User Manual

Page: 159 / 205

Appendix E: Equivalent-Time (ET) oscilloscope operation
Figure 20: Final channel delay values provide only noise in Y polarization
Hybrid calibration (ET)
This is a factory calibration. Imperfections in the OM4000 instrument receiver
are corrected using a factory-supplied calibration table. Check the Setup tab
for a green indicator to be sure the OUI is successfully retrieving the Reference
laser (Local Oscillator) frequency and power which are needed to choose the
correction factors from the calibration table. The table is the pHybCalib.mat
fi le in the ExecFiles directory.
You can verify you have a valid pHybCalib fi le by connecting to an oscilloscope,
typing pHybInUse in the MATLAB Engine Window, and clicking Single.
Similarly, EqFiltInUse shows the equalization
fi lter in use (if any).
The information statement contains the serial number, date of calibration, and
other notes about the calibration. If the serial number is correct then you have
the proper
fi le.
The following procedure can be used to verify and correct the calibration at a
single wavelength using a minimum of external hardware. This procedure assumes
that “Laser 1” and Laser 2” can be tuned to the same wavelength. It is easiest if
you have a polarization controller before the signal input, but the instructions are
written assuming you are moving the
fi ber around to change the input polarization.
OM4000D Series Coherent Lightwave Signal Analyzer 135