SV: Re: [sdiy] Noise as one unsteady tone!

[karl dalen]

--- Richard Wentk <richard at skydancer.com> skrev:

> At 12:07 05/09/2005, Magnus Danielson wrote:
> 
> >If you have a very selective filter you will find an unstable "tone"
> anywhere
> >you look, but what you hear is nothing but a narrow filter stimulated by
> noise
> >and not a characteristic of the noise itself. Not that it is not usefull,
> but
> >it is a different matter.
> 
> This is one of those times where theory collides with the real world.
> 
> In reality if you patch together enough sine oscillators - like a few 
> thousand - spread randomly across the frequency band, you get a reasonable 
> approximation of noise.

The reason i asked  was that i recently did some laborating with
PM, two VCOs and a delay line, this gives pass zero modulation, 
but strangely enough it sounds better then two pass zero oscillator,
one modulating each other, more dynamic, the wave looks different too.

In the PM example modulate enough and noise are created wich would be 
the same as your suggestion, ie at strong modulations the wave folds
over so many times and by doing so the amount of dissplaced overtones
in the end creates noise. Supricingly it seams, at least on the scope,
the power spectrum of the noise seams quite uniform!

So, then i comes to this, i have two VCOs and a delay line both
a reproducing a steady tone, one are used as carrier wave the other
modulates the time delay, enough modulation and i have noise, 
the fundamental and all the overtones move up and down in 
frequency to the frequency of the modulator wich tells us
that noise can be of different origin, tousands of steady 
sine waves or a simple mowing frequency PM setup!....No? 
  
KD