Fwd: [sdiy] FM math question

[Mattias Rickardsson]

---------- Forwarded message ----------
From: Mattias Rickardsson <mr at analogue.org>
Date: Thu, 16 Oct 2008 13:35:58 +0200
Subject: Re: [sdiy] FM math question
To: ASSI <Stromeko at nexgo.de>

I don't understand why a  sawtooth core -> tri shaper -> sine shaper
would not be a phase-to-sine mapping.
But OTOH I will not have access to the web & e-m forum until next
week, so I might have missed something vital.

/mr


2008/10/15, ASSI <Stromeko at nexgo.de>:
> On Mittwoch 15 Oktober 2008, Magnus Danielson wrote:
>> As you waveshape to sine it is very simple and infact maps very
>> neatly into the theory.
>
> I don't think he does what you describe.  From the electro-music
> thread the signal path appears to be an (analog) sawtooth core into a
> fullwave rectifier into an OTA sine shaper.  Unless I'm missing
> something, there is no phase-to-sine mapping anywhere in this signal
> path, but there are two nonlinearities.  The question posed by Ian
> (again if I understand it correctly) now is why the resulting signal
> has approximately the same spectrum as doing a PM on a sinewave.
>
>> This is expected.
>
> Tell me how. :-)  A somewhat unscientific argument would be that both
> nonlinearities produce spectra with fast decaying tails, so you could
> explain why the higher order modulation products don't end up
> counting much in the grander scheme of things.
>
>
>
> Achim.
> --
> +<[Q+ Matrix-12 WAVE#46+305 Neuron microQkb Andromeda XTk]>+
>
> Waldorf MIDI Implementation & additional documentation:
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