Waveform Measurements
The Waveform Measurement Process
Determining rising and falling edges
The nal analysis needed to make timing measurements is to dene the
transition points of the waveform through the threshold levels and to dene
the rising and falling edges. A rising edge is dened as a transition that
passes through the lower, middle, and upper threshold levels. A falling edge
is dened as a transition that passes through the upper, middle, and lower
threshold levels.For an edge to be present and dened, it must complete the
transition through all three threshold levels.
Once the transition points and edges are identied, the instrument next
calculates timing
measurements (rise
time,
fall
time
,
and
frequency).
Finally
,
it calculates
voltage measurements
that need
timing
information
(Vrms
cycle
and V
avg cycle)
as
shown
in
Figure
7-6
.
Figure 7-6.
Thresholds are used to determine edges.
7-11