[aprssig] PSK31 on HF APRS?

[Jim Lux]

I looked into this a while ago.. the problem is that PSK31 is really a 
keyboard to keyboard, non FEC kind of protocol, and doesn't lend itself to 
a "packet" kind of communications.  Something like MFSK16 might be a better 
choice, or one of the many multitone schemes.