Agilent Technologies 22A, 54621D, 24A, 42A, 54621A, 41A manual To set holdoff Holdoff Operating Hints

Triggering the Oscilloscope

To set holdoff

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 scope could trigger on each of the crossings, producing a confusing waveform. With holdoff set correctly, the scope 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 re-adjust 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 holdoff to this number.

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