[aprssig] Suggestions for modem designs?

[Rich Mulvey]

Hi All:

   I'm in the midst of working on an embedded APRS tool using the 
Parallax Propeller chip.  ( http://www.parallax.com/propeller/index.asp 
).  Right now, I'm working on having it decode APRS packets over a 
serial link, as if from a TNC.

   The next step is to actually have it decode APRS packets off the 
air.  Therefore, I'm looking for a good design for a 1200bps modem.  
There are a number of MX614-based ones out there, for example, some of 
which are pretty minimal, others that have more front-end filtering, etc.

   Can anyone suggest particualr implementations that work well?  They 
don't have to be 614 based - they just seem to be the most common ones 
I've run across.  I want something that handles both TX and RX, as well.

Thanks!

- Rich