[sdiy] re:Noise as one unsteady tone!

[karl dalen]

No, i change my mind, the overtones are steady but
dissplaced in the frequency spectrum due to the
modulation!.........No? :-)


-- karl dalen <dalenkarl at yahoo.se> skrev:

> 
> --- 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
> 
>