Tektronix OM4006D, User Manual

Page: 167 / 205

Appendix E: Equivalent-Time (ET) oscilloscope operation
This control reduces the need to use the oscilloscope front-panel controls while
using the OUI. The resolution readout is provided for convenience.
Analysis Parameters window (ET)
(See page 32, Analysis Parameters window .)
The following controls are relevant to Equivalent Time processing:
Signal Type : Chooses the type of signal to be analyzed and so also the
algorithms to be applied corresponding to that type.
Pure Phase Modulation : Sets the clock recovery for when there is no
amplitude modulation.
Clock Frequency : Is the nominal frequency of the data clock bounded by
a low (Low) and a high frequency (High) provided the clock signal power
is suf
fi cient.
Assume Orthogonal Polarizations : Is not yet implemented for ET mode
2nd Phase Estimate : Is not yet implemented for ET mode
Phase estimation time constant parameter : The parameter used in phase
estimation which depends on laser linewidth and noise. The default of 0.8 is
usually
fi ne.
Balanced Differential Detection : Not yet implemented for ET mode.
Continuous traces : Checking this box ensures that the fi ne traces connecting
the constellation points will be drawn. If unchecked, the traces will be
suppressed for calculation speed if the calculations are not needed for other
plots such as eye diagrams.
Mask Threshold : The ratio of radius to symbol spacing used for the circular
constellation masks.
Symbol Center Width : The fraction of the eye-center that should be
considered “symbol center” for the purpose of certain calculations such as
OM4000D Series Coherent Lightwave Signal Analyzer 143