SV: Re: [sdiy] FIlter FM=narrow band 2 quadrant spectrum modulation?

[karl dalen]

--- Sean Costello <seancostello2003 at comcast.net> skrev:

> Don't forget that modulating a 4 pole filter also results in phase
> modulation, which is similar to true frequency modulation.

You just said it!

Recalling years ago of disscussion of wheter FM was PM, and recently Magnus
saying PM are just more Bessel functions open up then TZFM, so where's the
diference between these all? Not to mention the latest delay based FM
discussion, that really opens up the bessels!

It would be interesting to have someone clarifying
what is what and when, in a simple clear manner exluding the hoopla maths!?

KD
 
> I would just call it Filter FM.
> 
> Sean Costello
> 
> 
> ----- Original Message ----- 
> From: "karl dalen" <dalenkarl at yahoo.se>
> To: <synth-diy at dropmix.xs4all.nl>
> Sent: Wednesday, October 26, 2005 12:49 PM
> Subject: [sdiy] FIlter FM=narrow band 2 quadrant spectrum modulation?
> 
> 
> > I just relized im unshure!
> >
> > What are filter FM actually?
> >
> > The test:
> >
> > Lets modulate a 4 pole LP filter (resonance at zero)
> > with a sine wave, and a saw wave as the inputsignal
> > to the filter, by mowing the poles of the filter up and down,
> > isnt this actually band limited AM? Or band selective AM!
> > Or perhaps narrow band 2 quadrant spectrum modulation?
> > (quite fancy naming) :-)
> >
> > Under what synthese label should this actually be placed?
> > Can it be labeled?
> >
> > Should this be valid all the way up to self oscillation
> > of the filter and then it be renamed Filter FM as usuall!
> > (asuming that the input signal has been remowed).
> >
> > Lets say we do the same but now with hertz wide BP filter,
> > all we would hear are a series of harmonics fading in and out,
> > done rappidly wouldent that resemble more to oscillator FM soundwise?
> > Using square wave as inputcarrier would be interesting, what would that
> > resemble in ordinary oscillator FM? (since only odd harmonics are AM'ed!)
> >
> > KD
> 
>