Average waveform display looks choppy?

[jdepalma]

I am using a Pico Tech USB oscilloscope to collect average signal traces of an input signal. I plot the data in a waveform graph. I have included an image of what I get. When I crank up the averages to very high amounts (well over 100), the displayed data in the waveform graph looks hoppy and not smooth/rounded as I would expect for average traces. It almost looks like 8-bit noise to an extent, but I am collecting at 16-bit. Am I using the wrong display format/type or how do I change the display resolution of the displayed waveform? I have tried changing as many options as I could but there was nothing to change about sampling rate or display resolution.  FYI: The scope trigger is at 10 Hz and the waveform is a 64 bit double precision nubmer.  Thanks!

[jdepalma]

Something else I thought about - is it because the delta t of the waveform is too large?  If my understanding is correct, the waveform assume a uniform time interval for its plot.  How is this set in LabView and can it be changed?

[Bob_Schor]

That's a bad result?  Looks pretty good to me!

Please attach your code (by attaching one or more VIs, or if there are too many, compress the folder they are in and attach the .ZIP file) so we can better understand what you are doing and can make more useful suggestions.

P.S.  What do you mean, "crank up the averages to very high amounts"?  Do you mean "average many samples", or "turn up the functional gain of the oscilloscope"?  If the latter, you need to think if you are looking at digitization noise, i.e. at single bits changing.

Bob Schor

[jdepalma]

Hi Bob, 

Thanks for following up.  I have included the VI I use. It has a lot of proprietary stuff from Pico, but you'll see the point.  My data is a multi channel detector signal, and when I say  "crank up the averages to very high amounts" I mean average many samples.  In the screenshot I posted earlier, it was averaing 128 scans.  

I would have simply expected the resulting waveform to look more smooth than it does, but that may be more of the time interval of the waveform plot itself rather than any code I write.  Suggestions?  Thanks in advance.  

Joe