EXFO PSO-200 Optical Modulation Analyzer - Manual (Page 266)

Measurement Definitions
258 PSO-200
Measurements for Eye Diagrams
Measurements for Eye Diagrams
Eye diagram measurements refer to measurements conducted in
time-domain graphs primarily on I, Q tributaries (when measurements are
conducted on the magnitude or intensity of the signal, this is specified in
the definitions).
Some measurement parameters are only defined for specific modulation
formats and signals utilizing pulse carving, hence the composition of
measurements depends on the user input signal parameters (Modulation
and Bit Format, see Configuring the Input Signal on page 13).
Since the PSO-200 is a coherent optical modulation analyzer, it measures
the field of the signal, so all eye diagram measurements are computed on
field (for example, I, Q, and Magnitude graphs).
One and Zero Levels
The eye-mode measurements start out by measuring the one and zero
levels, since many other measurements depend on these values.

The one level, E
one
, represents the logic one level in the eye diagram,
determined by the mean level within the data measurement window.

The zero level, P
zero
, represents the logic zero level in the eye diagram,
determined by the mean level within the data measurement window.
Measurement window
One level
Histograms
Zero level