[sdiy] PM vs FM was: Re: Buchla 295 10-band comb filter topology

brianw brianw at audiobanshee.com
Fri Dec 2 08:50:47 CET 2022

Terminology abuse abounds in that article.

"peak amplitude" and "instantaneous amplitude" seem like misnomers.

Amplitude already refers to the peaks, so "peak amplitude" is redundant.

Instantaneous values do not have an amplitude, because amplitude is "the maximum extent of a vibration or oscillation," and not every sample in a period is a maximum. By definition, amplitude must span all values in the period, and thus it cannot be instantaneous. You can have extremely short-term amplitude, but it must at least span one cycle. Usually, though amplitude is measured over multiple cycles, I'd assume, at least based on standards like VU.


p.s. I didn't re-send the image that was attached, so look at your email history for the quote. ;-)

On Dec 1, 2022, at 11:29 PM, Donald Tillman <don at till.com> wrote:
> The confusion started with the first equation in Chowning's article:
> <Screen Shot 2022-12-01 at 11.25.55 PM.png>
> I can't help but think that the guy really, really likes calling it frequency modulation.
>   -- Don

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