Measurement Computing eZ-Analyst rev.14.1 - Manual (Page 45)

eZ-Analyst 978791 Edit Menu 4-9
Shifting a Waveform with Pre-Trigger and Post-Trigger
Note: The trigger level is an absolute signal level that must be within the FSV.
Reference Notes:
The following sections of this document contain information that closely relates to
the subject of Capturing Transient Data. Reading over the following material should
improve your understanding of the important concepts involved.
 Capturing Transient Data, page 4-8.
 Recording Setup, page 4-30.
 Block Rejection Tab, page 4-34.
 Considerations Regarding Double Hammer Rejection, page 4-35.
(A) Setting Signal Position
Once an acceptable trigger level
has been ascertained,
positioning the signal within a
block of sampled data (and in
the display window) is the next
consideration. Often it is
necessary to capture the events
that lead up to the trigger point.
If this is the situation then
positioning should be set for
Pre-trigger capturing. On the
other hand, if the signal of
interest occurs after the trigger
point, then positioning should be
set for Post-Trigger capturing.
(B) Normal Trigger
Normal Triggering is obtained by
specifying zero for the Pre-
Trigger and zero for the Post-
Trigger; where the trigger point
occurs at the first sample point
as pictured in the figure to the
left.
(C) Pre-Triggering
To capture information before
the trigger point, select Pre-
Trigger and specify a percentage
of the frame size. This has the
effect of shifting the waveform
to the right as pictured in the
figure.
(D) Post-Trigger
Post-Trigger is the opposite of
Pre-Trigger. Post-Trigger
causes eZ-Analyst to wait “n%”
samples before it begins filling a
block of data. This has the effect
of shifting the signal to the left.
(D)
Post-Trigger