Even entry-level oscilloscopes today have simple math functions such as adding or subtracting two channels. But as [Arthur Pini] notes, more advanced scopes can now even do integration and differentiation. He writes about using these tools to make measurements on capacitors and inductors. The post in EDN is worth a read, even if your scope doesn’t offer this sort of math yet.
It makes sense that capacitors and inductors would benefit from this feature. After all, the current through a capacitor, for example, is proportional to the rate of change in the voltage across it. That’s a derivative. Since the scope can measure voltages, it can also differentiate to find the current.
The same idea applies to inductors, where the current through an inductor is related to the integral of the voltage across it. It is a simple matter to measure the voltages and perform an integration to determine the current.
All of this, of course, relates to differential equations and calculus. While calculus has a reputation for being hard, it actually makes sense if you want to work with quantities that change over time. Once you realize that a sine wave is just a fixed spot on a rotating wheel, everything comes together nicely. You could, of course, grab discrete samples from any scope and use numerical methods to get the same results. But it is much easier if your scope can do it for you.
“But as [Arthur Pini] notes, more advanced scopes can now even do integration and differentiation.”
Most half-decent scopes have had these functions for years/decades—just saying. Pretty trivial given it’s just adding & subtracting samples…
I’ve found differentiation to be iffy, given its sensitivity to noise. If you can precede it with a scope’s LP filter (and THAT’s a much rarer function), I expect it would be helpful.
And still, if you want an oscilloscope with “power analysis”, you have to pay quite a lot extra. More then I’m willing to spend. I’m not sure what it does exactly, but I guess it can keep track of things like power consumption of a gadget, or (dis)charge of a battery with addition of a shunt resistor.
Analysis of harmonics in AC systems is also a part of that, but all digital scopes I know also aldready do FFT, so that is not much special either.
Functions like this do make it more useful to have a 12 bit resolution on your scope.
My early 1990s HP1653B a digital scope and does not do FFT. I don’t know when FFT became common on digital scopes.
My 1990 LeCroy 9400 does FFTs.
Durned thing has a 68000 in it.
Isn’t all this stuff that’s easy to do as long as it’s analog ?
I vaguely remember watching someone shooting Polaroids of a scope because doing the math would be too hard
Back in the very old days of NMR spectroscopy, we’d use scissors to cut out the shape of a peak on the chart recorder paper, and weigh the piece on a scale to integrate under the curve.
Yep, same for a lot of instrument signals from voltammetry to gas chromatography. Weigh the density of the paper first then cut cut cut.
Most nmrs now have hardware that fills a mobile server rack and a computer for analysis. I have seen some where the signal was displayed on an oscilloscope but it was an old research project.
Sometimes I think we lost something from these days. Sometimes I’m glad we aren’t forced into them.