Perhaps these will help.
http://tams-www.informatik.uni-hamburg.de/applets/hades/webdemos/45-misc/40-modem/fsk-modulator.html
**broken link removed**
http://tams-www.informatik.uni-hamburg.de/applets/hades/webdemos/45-misc/40-modem/fsk-modulator.html
**broken link removed**
Last edited: