Hey thanks for the welcome Tautech, and thanks for the the answers everyone! Great community you have here.
Tautech, you're right I am definitely looking for the
Peak Slew Rate , and I'm sad to hear that there's no simple function to tell me this. Oh well, I'll have to find it a different way.
[...] So in this case the Slew Rate measurement should appear in Units of A/s not V/s. This is a bug I've noted before, and in the latest firmware it seems to be (sometimes) fixed, [...]
As for the units, I'm looking for current -- kA/s. I'm using a current probe, and I've changed the unit of my channel to [A]mps, but as alsetalokin4017 points out my firmware is an older version (04.03, not either of the SPs) so apparently the labeling is incorrect, however the actual measurement values are fine so it's mostly a moot point. I don't think I want to risk updating the firmware as I've read this is irreversible on the DS1054z.
Alsetalokin4017
and Tggzzz point out that
the DS1054Z's math Diff function is seriously unusable. Too bad. Thanks for the scopeshots alsetalokin4017! That has been really good to see someone else's scopeshots at a later firmware, which show the same problems I'm having with it now. It's not just me
The amplitude of the "Diff" waveform changes drastically depending on the "Smooth" setting. So one can apparently select whatever value one likes for this "measurement".
That has been my experience as well. I can get the Diff waveform to look "right" like a derivative, but the values are basically garbage as best I can tell. Nothing I can use for the actual takeaway values I need.
Super nice Tek Scope comparison!So check it out. I got my hands on a super nice Tek scope with another current probe to see the difference. With just some basic fiddling I got exactly what I was looking for. Note "M1" which is "DIFF(Ch4)" -- the same function we're attempting on the DS1054z, and also note the circled "M1: Max" measurement --
exactly what I'm looking for!!:
That peak value on Tek's Math Diff is what I'm looking for -- peak positive slew.
[...] differentiation is inherently sensitive to noise.
Totally right. On the Tek, I started with a scope screen full of noise, and had to dial down the sampling rate (among a few other tricks) to get a usable curve. So I should just be able to apply smoothing and averaging on the Rigol to get the same value, but...
I noticed also that the amplitude of the Diff trace varies with timebase settings too.
I noticed this too, and this is
not something that happened on the Tek scope. On the Tek there was a ton of noise, but there was still an underlying curve to the madness (sorry, wish I had a screenshot pre-averaging). Changing the timebase or averaging\smoothing did not fundamentally change the values on the Tek but
did on the Rigol.
This leads me to believe that the Diff function on the Rigol is beyond unusable and is simply bugged. However, I'm still all ears if there's a specific setting I'm missing!
Thanks again everyone, I'll update again if I figure out a solution for the Rigol DS1054z math Diff.