Tektronix TBS2072, Руководство пользователя

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Trigger setup
Triggering on a runt pulse
Use this procedure to set the oscilloscope to trigger when a runt pulse occurs. You can also trigger when a runt pulse is less
than, greater than, equal to, or not equal to a set time period (width).
A runt pulse is a pulse that crosses one threshold level but fails to cross a second threshold before recrossing the fi rst.
Therefore, a runt trigger needs two threshold levels to de fi ne the two levels that a signal must pass through to be considered
a valid (nonrunt) signal. (See page 27, Available trigger types .)
Runt pulse triggering is most often used to troubleshoot or analyze digital signals.
The minimum runt pulse width setting is 1 ns.
1. Push the Trigger Menu front-panel button.
2. Push the Type side-menu button.
3. Use the Multipurpose knob to select and click Runt .
4. Push the Source side-menu button and use the Multipurpose knob to select and click the channel to use as the trigger
signal source, or select AC Line to use the AC power source frequency as the trigger signal.
5. Push the Polarity side-menu button and use the Multipurpose knob to select and click the runt pulse polarity (positive,
negative, or either) to trigger on.
6. Push the Thresholds side-menu button and use the Multipurpose knob to select and click the trigger levels (thresholds) to
use to detect a runt pulse:
Click High and use the Multipurpose knob to manually set the level that de fi nes a valid high signal threshold level.
Click Low and use the Multipurpose knob to manually set the level that de fi nes a valid low signal threshold level.
Click Choose Preset and use the Multipurpose knob to set the trigger threshold levels to prede fi ned signal logic family
levels (TTL, CMOS, ECL, and so on) or to 0.
7. Push the Trigger When side-menu button and use the Multipurpose knob to select and click Runt Occurs to trigger on
any runt event. If triggering on a runt width, use the Multipurpose knob to select and click the runt pulse width condition to
test for, and enter the runt width time parameter.
38 TBS2000 Series User Manual