[sdiy] Measuring THD of a sine wave

[cheater cheater]

You use a THD meter, a standardized piece of equipment, which contains
everything Don mentioned inside it. Maybe others mentioned the same
stuff, I haven't read all the posts. Going into it too much is beside
the point, just read up on how a THD meter works.

On Sat, Nov 12, 2022 at 1:43 AM Tiago Ventura via Synth-diy
<synth-diy at synth-diy.org> wrote:
>
> Greetings folks!
>
> The technical literature in general, *whenever* it bumps into the
> topic of sine wave generation techniques the difficulty of generating
> such a signal is always mentioned. And then, several techniques and
> circuits are presented and analyzed. The THD% of these circuits are
> mentioned for comparison purposes.
>
> How the heck are these distortion levels measured or calculated in practice?
> What are the main techniques and procedures applied in order to
> measure the total harmonic distortion (THD%) of a given sine wave?
>
> The idea of using a second sine wave as a comparative reference of
> what is "pure" is pretty obvious, but what kind of source would be
> able to present an acceptable "purity" for this purpose? (a digital
> source sounds ridiculous for this but I can't think about anything
> else!)
>
> Remembering that it is essential to also calculate the accuracy of
> this measurement. Are there other alternative techniques for making
> such a measurement? Is there anything available in the technical
> literature exploring this subject?
>
> Any thoughts/comments/suggestions would be greatly appreciated.
>
> Tiago Ventura
>
> Greetings from Porto Alegre/Brazil
> -30.03376474999071, -51.238242916392814
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