[sdiy] FSK specifications

[media.nai at rcn.com]

At 9:52 AM -0500 03/20/02, Dave Magnuson wrote:
>
>I just had a silly idea that may or may not work.  I was wondering if it
>would be possible to use clock dividers to derive 1/4 1/8 and 1/16 notes
>from the FSK output of my sequencer.
>
>From my understanding, FSK is simply a pulse wave clock, right?  How many
>ppqn will it generally have?  I just figure this may be an easy way to
>"cheat" and avoid using my DIN-Sync convreter to feed my clock dividers.

I think it depends on the device.  As far as I know there is no official
FSK spec.  While it could be a pulse wave, its carrier (or is that
modulator?? :) frequency is not a multiple of, nor related to the tempo.
In the case of the TR-909 it alternates between a 1200Hz and 2400Hz pulse
"at every half-period of T which is 1/24 of the time required for most of
Roland products to process a quarter note."  So it has 48 shifts per
quarter note.  I'm thinking you would have to demodulate the signal first,
then divide it down.  Imho, using DIN sync would be much easier.