Scientific SMO1000E, User Manual

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Scientific
SMO1000E 68/185
Trigger Holdoff
Trigger holdoff can be used to stably trigger the complex waveforms (such as pulse
series). Holdoff time is the amount of time that the oscilloscope waits before re-arming
the trigger circuitry. 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 below, set the
holdoff time to be >200 ns but <600 ns.
Holdoff
200ns 600ns
Trigger Point
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.
Only edge trigger and serial trigger have holdoff option. The holdoff time of the
oscilloscope is adjustable from 100ns to 1.5s.
1. Press the Stop button, and then use the Horizontal Position Knob and the
Horizontal Scale Knob to find where the waveform repeats. Measure this time
using cursors; then, set the holdoff.
2. Press the Setup button on the front panel to enter the TRIGGER function menu. The
default trigger type is edge.
3. Press the Holdoff Close softkey; and then turn the Universal Knob to set the
desired holdoff time.
Note: adjust the time scale and horizontal position will not affect the holdoff time.