BK Precision 2194, User Manual

Page: 42 / 139

Trigger 42
6.5 Trigger Holdoff
Trigger holdoff can be used to add an additional, user-defined delay to the re-arming of the trigger circuit. This provides
control over how rapidly, or how often, the oscilloscope can be triggered. The oscilloscope will not trigger until the
holdoff time expires.
Use the holdoff to trigger on repetitive waveforms that have multiple edges (or other events) between waveform repetitions.
You can also use holdoff to trigger on the first edge of a burst when you know the minimum time between bursts.
For example, to get a stable trigger on the repetitive pulse burst shown in figure 6.5 set the holdoff time to be >200 ns
but <400 ns.
Figure 6.5 Holdoff
The correct holdoff setting is typically slightly less than one repetition of the waveform. Set the holdoff to this time to
generate a unique trigger point for a repetitive waveform.
Note:
Only edge trigger and serial trigger have holdoff option. The holdoff is adjustable from 100 ns to 1.5 s.
To find the repetition of the waveform:
1. Press the Stop key to stop data acquisition.
2. Turn the Horizontal Position Knob and the Horizontal Scale Knob to find where the waveform repeats.
3. Measure the time using the cursors function.
4. Set the Holdoff time.
To set the Holdoff time.
1. Press the Setup key to enter the Trigger menu.
2. Press the Holdoff Close softkey to enable Holdoff.
3. Turn the Universal Knob to set the desired holdoff time.
– Push the Universal Knob to open the numeric keypad.
Note:
Adjusting the time scale and horizontal position will not affect the holdoff time.