Feedback in FM synthesis

[Martin Czech]

:::John Chowning's original patent is FM.  US patent 4,018,121:
:::http://www.patents.ibm.com/details?pn=US04018121__

In this patent I see the formula:
 
e=A*sin(wc*t+I*sin(wm*t)) (page 19 of 32, second row, line 7 or so)

I think I is intended as modulation parameter independend from wm.
If this is the case, this formula describes PM and not FM.

For FM it should be:

e=A*sin(wc*t+I/wm*sin(wm*t)) 

(if we assume static wm), the 1/wm term comes from integration
and ensures equal frequency modulation for all wm.


I think Chowning was not aware of the difference.
He was always dealing with PM.

m.c.