Eye, Mask and Eyeline Mode Measurement Tutorials
Making Eye Diagram Measurements
Measuring rise time
The rising edge of a pulse is dened as a transition that passes through
the lower, middle, and upper threshold or logic levels.For an edge to be
measured, it must complete the transition through all three threshold
levels. Once a rising transition has been determined, the rise time may be
determined by the following:
(time at the upper threshold crossing)
0
(time at the lower threshold
crossing) = Rise time
The instrument
has two
standard and
a
user-dened
threshold
level
for
which
rise time
may be
measured. The
rst
is
the
10%
to
the
90%
point
on
the
transition, and
the second
is
the
20%
to
the
80%
point
on
the
transition.
The
20%
to
80%
transition
is
recommended
for
devices with
signicant pulse
distortion.
Using
the
user-dened
threshold
levels
,
any
point on
the transition
may
be
chosen.
The
measurement
threshold
can
be
changed
by
use
of
the
4
Dene
meas
5
menu.
Figure 5-10. Rise time measurement.
5-21