Tone Detection with Goertzel, but not DTMF.

*Sheepish Grin*  I guess I was slightly unreasonable asking for help
without fully specifying the limitations of what I had to work with.  

The RAM is very limited in the way it can be accessed.  (basically
increment and decrement. With a few address that can be inconveniently
stored and retrieved.) And the ALU is limited to specific functions as
well (Conveniently for me, that doesn't include an XOR.)  The hardware
wasn't intended to do more than just simple FIR filtering of signals
without some tricky interleaving; I was just trying to figure out a way to
shove a square design into some round hardware.   

I heard somewhere that "Engineering is the art of making what you want
from things you can get." So I gave it a shot =).  It seems I'm not a real
engineer yet.  :(


> So? Is it a problem to implement a basic frequency counter to
demodulate
> the FSK?

I'll go find out what a basic frequency counter is and decide from there.
:) 

I spoke with a guy at work who knows infinitely more about DSP than I do
and he suggested looking at a "slicing algorithm to demodulate" the signal
instead of the filtering approach.  So for now, I guess I'll abandon my
friend, Herr Goertzel, and do some more reading.  

Thanks for all the input though, at least now I have a few more alleys to
stumble down before I give up and nix the idea of doing it in digital.

-JT