[linux-audio-dev] FM, Phase Modulation and The Wiki

[Simon Jenkins]

On Wed, 2005-06-29 at 00:47 +0200, Jens M Andreasen wrote:
> On Tue, 2005-06-28 at 21:13 +0100, Simon Jenkins wrote:

> > It seems the difference is that PD works on individual cycles of the
> > modulated waveform. The wiki author guesses that there may be an extra
> > synching oscillator but in fact...

> This thread is about correcting some of the wrongs in the Wiki! (you
> damned dummy!)

erm... er... huh??? Thats what I was doing, wasn't it? Oh, hang on...
I'd clicked the link, so my comments actually apply to this page:

http://en.wikipedia.org/wiki/Phase_distortion_synthesis

> > 
> > "The scanning interval speeds up from 0 to [pi] and then slows down from
> > [pi] to 2 [pi]. The overall frequency is constant, according to the
> > pitch of the note, but the output waveform is no longer a sine".
> > 
> > ...somebody just did the math(s).
> > 
> Did not! Did perhaps? Did :)
> 
> Where is this from?

Its from this book:

http://mitpress.mit.edu/catalog/item/default.asp?ttype=2&tid=8218

The information can be second-sourced from this Sound-on-Sound tutorial:

http://www.soundonsound.com/sos/1997_articles/sep97/synthschool3.html

which was written by the co-author of The Casio CZ Book. There's a bit
more detail here too but unfortunately the diagrams are not online, only
the text is.

Simon