Waveforms scope averaging does not work for single acquisition?

[enelson]

I'm not sure if this is the right place to report what I think is a bug in waveforms.  I'm using version 3.16.3 64-bit on windows 10.

I was having difficulty using averaging in the scope timebase controls to eliminate some noise.  When I click on 'single' acquisition, the scope appears to trigger the appropriate number of times (e.g., 100) before displaying a new trace. But the noise is not reduced, as if the scope is showing me just the trace from the first (or maybe the last) trigger.

Clicking on 'run' similarly counts the appropriate number of triggers and then displays a new trace, but with the expected noise reduction from averaging.  I can then click on 'stop' to export the averaged traces, so I'm not stuck.

Hopefully this is easy to fix in subsequent versions of waveforms, so that a 'single' acquisition does the requested averaging.  I am otherwise having a great time so far with waveforms and my analog discovery 2.  Thanks!

[attila]

Hi @enelson

Thank you for the observation.
It is fixed for the next software build.

Edit: To overcome this problem with the current software set Oversampling to 1 

Edited June 24, 2021 by attila

[attila]

Hi @enelson

I think you are referring to the noise band.
Beside normal samples a smaller amount of noise (min/max) values are stored. This, to indicate glitches or higher frequency components that would be otherwise hidden by normal sampling.
This can be disabled individually under each channel option (gear) or under Option dropdown.

[enelson]

Hi @attila,

thanks for responding.  I'm not referring to the noise band, although that is a nice feature so thanks for having it.

Perhaps some screen snapshots will suffice to illustrate.  I'm measuring the voltage across a diode (channel 1) that is driven by a 2.5 V peak 1 kHz triangle wave (channel 2) through a 17.8k resistor.  I've zoomed the trace on one of the channel 1 peaks, where I see about a mV of noise in this channel 1 trace, taken with no averaging.  This noise is presumably due to the relatively noisy environment in my "lab".

Now if I average 100 traces, I expect the noise to be substantially reduced, perhaps by a factor of 10.  However, when I set averaging to 100 and press 'single' for a single acquisition, waveform counts 100 triggers and I get a trace like the following (after zooming again).  The noise is still there, contrary to my expectations for what averaging should do.

However, if I press 'run' instead of 'single', and then 'stop' some time after the 100 triggers, the zoomed trace below now looks very nice, with very little noise, in line with what I expect averaging should do.

So it looks to me like averaging is not really working when one requests a single acquisition.  It might be showing just the first (or last) of the 100 traces I requested waveforms to collect and average.

Thanks for looking at this again!

 

[enelson]

Thanks @attila!  Have a great day.

[attila]

Hi @enelson

It is fixed in the latest beta version:
https://forum.digilentinc.com/topic/8908-waveforms-beta-download/