Spent some time today evaluating Digital Comms/Modem ports for the amd64. I found 4 systems in the ports tree for FreeBSD and tried em all. Settled on gMFSK by Tomi Nanninen, OH2BNS. Nice interface and the DSP seems to be very sensitive. The system supports MFSK, RTTY, THROB, PSK31, MT63 and FeldHell.
I had a nice MFSK16 qso with WV7T, Mike in Colorado. Looking forward to trying the other modes.