EXFO PSO-200 Optical Modulation Analyzer - Manual (Page 55)

Customizing the Graph and Data Layout
Optical Modulation Analyzer 47
Pattern Diagrams
Pattern Diagrams
You can view all graphs (I/Q, intensity, magnitude, phase and EVM) as a
pattern instead of an eye diagram. The pattern diagram is a continuous
curve between different amplitude and/or phase states, as a function of
time. It helps viewing the capacity of the system to transmit all signal
combinations.
In standard sampling oscilloscopes, a pattern clock (which sends out a
pulse synchronized with the periodic pattern) may be used to trigger the
scope. In contrast, the PSO-200 uses a software algorithm to reconstruct
the pattern.
On pattern diagrams, the X axis is either symbol- or time-based. At a 100 %
zoom value, you can see the entire signal for the symbol pattern.
Y-Axis Auto Scaling (All Graphs)
The unit does not display intensity data (Y axis) in mW, but rather scales it
to a normalized unit. Each time you press Start (or Clear Data), the unit
computes a scaling factor based on the first burst, and uses it for
subsequent bursts.
Note: To see the difference in intensity between the X and Y polarizations,
compare the Power Level values from both result tables. You can also see
the values in the constellation charts.
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