Tektronix CSA7154, User Manual

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Triggering
3- 98
CSA7000 Series, TDS7000 Series, & TDS6000 Series Instruments User Manual
Overview Control elements and resources To trigger on a runt pulse (Cont.)
Set the
thresholds
7. To set the two threshold levels used in detecting a runt
pulse, touch Upper Limit or Lower Limit, and use the
multipurpose knob or keypad to set the values for the
upper and lower thresholds.
Note.
To use the trigger bar to set the threshold levels, touch
the Disp button, select the Objects tab, and then touch Long
to display the long trigger bar.
Note the position of the trigger indicator. Triggering occurs at
the point the pulse returns over the first (lower) threshold
going negative without crossing the second threshold level
(upper). The polarity selected in the Polarity window
determines the order that the threshold must be crossed for a
runt trigger to occur:
H
Positive requires that the lower threshold must be
first crossed going positive, then recrossed going
negative without the upper threshold being crossed
at all.
H
Negative requires that the upper threshold must be
first crossed going negative, then recrossed going
positive without the lower threshold being crossed
at all.
H
Either requires only that either one of the
thresholds must be first crossed going in either
direction, then recrossed going in the opposite
direction without the other threshold being crossed
at all.
For all three polarity settings, triggering occurs at the
point the runt pulse recrosses its first threshold.
Selected trigger bar at
upper threshold.
Runt pulse crosses first threshold only, recrosses first
threshold level, and triggers acquisition
Unselected trigger bar
at lower threshold.