Author Topic: EEVblog #1320 - Premature Oscilloscope Triggering  (Read 3264 times)

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Offline David Hess

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Re: EEVblog #1320 - Premature Oscilloscope Triggering
« Reply #50 on: July 28, 2020, 06:42:58 pm »
Looks like we may have a good test?   Inspect the jitter between a square wave input signal and the trigger output.

If the jitter is always a multiple of the sample rate on the analog inputs, the scope uses digital triggering.  Don't try this on the digital channels, though, since they may be sample aligned even with analog triggering.

It should not be necessary to rely on the "trigger" output unless the trigger output is what you want to test.  Comparing the display of the digital in and vertical in with triggering provided by the digital in, vertical in, and external trigger in if present should reveal as much as possible.  The edge should be fast enough to approach the rise time of the vertical input but that is not difficult to achieve.

The difference in available trigger modes between the three inputs also reveals something of the design.

In practice, the difference between triggering of the digital inputs and vertical inputs should never come up.  If it does, then a faster logic analyzer should be used.
« Last Edit: July 28, 2020, 06:47:55 pm by David Hess »
 


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