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Hi all I am trying to sample a 5 MHz square wave signal with jitter as a source of entropy using my oscilloscope (Tektronix MSO 3054), however, I don't know how to turn off the trigger while I am sampling (at a rate of 5 MHz) the data. I need to turn off the trigger because it affects the entropy of the measured voltage points (causing most of the measured points to be zero). I am also trying to collect this data from my pc using NI Signal Express which seems to require a trigger to be set until data collection can start. Any guidance would be appreciated on how to sample this data without using a trigger.

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  • \$\begingroup\$ Can your scope trigger on it's own noise? \$\endgroup\$ – Jeroen3 Dec 7 '17 at 20:47
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There must be some kind of trigger to tell the scope to start sampling.

If you want a trigger that isn't correlated with any event in the input signal, traditionally you would trigger off of the 50 or 60 Hz mains supply of the scope. Most scopes have a built in capability to trigger off the mains or "line" voltage.

Other options provided by many or most scopes:

  • Trigger off of a front panel push-button

  • Trigger off a remote interface (GPIB or serial) command

  • Use auto-trigger mode and set the edge trigger level to where the input signal will never cause a synchronized trigger.

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