To Trigger On A Complex Waveform - Agilent Technologies 54610B User's And Service Manual

Operating Your Oscilloscope

To trigger on a complex waveform

To trigger on a complex waveform
The difficulty in viewing a complex waveform is triggering on the signal.
Figure 2-3 shows a complex waveform that is not synchronized with the
trigger.
The simplest trigger method is to trigger the oscilloscope on a sync pulse that
is associated with the waveform. See "To trigger the oscilloscope" on page
1-10. If there is no sync pulse, use the following procedure to trigger on a
periodic complex waveform.
Connect a signal to the oscilloscope.
1
Set the trigger level to the middle of the waveform.
2
Adjust the Holdoff knob to synchronize the trigger of the
3
oscilloscope with the complex waveform.
By setting the Holdoff to synchronize the trigger, the oscilloscope ignores the
trigger that results in figure 2-3, and waits for the trigger that results in figure
2-4. Also notice in figure 2-3 that the trigger is stable, but the waveform is
not synchronized with the trigger.
Holdoff operating hints
1 The advantage of digital holdoff is that it is a fixed number. As a result,
changing the time base settings does not affect the holdoff number; so, the
oscilloscope remains triggered. In contrast, the holdoff in analog oscilloscopes
is a function of the time base setting making it necessary to readjust the holdoff
each time you change the time base setting.
2 The rate of change of the holdoff adjustment knob depends on the time base
setting you have selected. If you need a lengthy holdoff setting, increase the
time/div setting on the time base, then make your coarse holdoff adjustment.
Now switch back to the original time/div setting and make the fine adjustment to
reach the exact amount you want.
2-12