Triggering the Oscilloscope 46000 Series Oscilloscope User’s Guide 135
Holdoff Operating Hints
Holdoff keeps a trigger from occurring until after a certain amount of time has
passed since the last trigger. This feature is valuable when a waveform crosses
the trigger level multiple times during one period of the waveform.
Without holdoff, the oscilloscope could trigger on each of the crossings,
producing a confusing waveform. With holdoff set correctly, the oscilloscope
always triggers on the same crossing. The correct holdoff setting is typically
slightly less than one period. Set the holdoff to this time to generate a unique
trigger point. This action works even though many waveform periods pass
between triggers, because the holdoff circuit operates on the input signal
continuously.
Changing the time base settings does not affect the holdoff number. 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.
With Agilent’s MegaZoom technology, you can press Stop, then pan and zoom
through the data to find where it repeats. Measure this time using the cursors,
then set the holdoff.