[sdiy] FM math question

[harrybissell at wowway.com]

Unless the modulation amount is really high, wach individual
saw cycle will be essentially linear... think frequency changes between
cycles and each individual cycle is essentially one frequency. In this case
the triangle waves will not be distorted... and the sine waves will be 
very uhhh... sinusoidal.

I have some simulations and the end result does look like a modulated sine
wave.  Now if you make each cycle REALLY non-linear... that will not be the
case anymore.

The typical OTA based sine shaper will probably reduce distortion in most
cases  (ie remove harmonic content)

H^) harry

Ian's idea has some real merits...


On Thu, 16 Oct 2008 12:53:07 -0600, Ian Fritz wrote
> At 11:39 AM 10/16/2008, Mattias Rickardsson wrote:
> >A saw core vco with a saw->tri->sin shaper is a vc sine oscillator.
> >You then modulate this sine with another sine, and get an appropriate result.
> >
> >Am I missing something?
> 
> Well, you don't modulate the final sine.  The modulation is of the 
> core saw, before the wave multiplication.  Since the multiplication 
> is a nonlinear process it would seem to me that the results would be 
> different for the two cases.  Maybe not. <shrug>
> 
>    Ian
> 
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Harry Bissell & Nora Abdullah 4eva