RE(2): spectrum of PWM

[Adolf Stalin]

> > 	>You should be able to model it using Bessel functions.
> > 	>
> > 	>Consider this:
> > 	>
> > 	>You have two sawtooth waveforms which are at exactly the same
> > 	>frequency (SHARP! THE same) which are added together 1:-1. One of
> > these
> > 	>are phase-modulated in the relation to the other. Now, as we change
> > 	>the phase modulation will the resulting pulse-width change. Now, we
> > 	>can handle this using Bessel functions in the frequency plane.
> > 	>I think scetching something along these lines will make you arive
> > at
> > 	>an exact solution.
> > 	>
> > 	>Is that sufficient for you?
> >
>	>Excellent. I think that's the solution !
>
>I was too fast. That's the saw-based PWM (minus DC shift) that is modelled.

Exactly was i tought to, to fast you where!

>Any ideas for the triangle-based PWM ?

180 deg up 180 deg down i used at my osc
http://home.swipnet.se/~w-133242/4046.htm
If it can be of use?!

>(With the "center of gravity" of each pulse being invariant, rather >than 
>the rising edge as in the saw-PWM case)

What exactly are trying to achieve? PWM FM or what?

BJ
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