ge0rg
Add support HF
The AFSK mechanism is rather prone to errors (bad audio cables, accidental ring tones), so I'd rather suggest using a Bluetooth based TNC and implement the 300bd mode there. However, I'm not opposed to adding different baud rates to the internal AFSK code, I just don't know the right parameters and don't have the radio gear to test it.
The AFSK is a 200Hz shift at 300 baud; different modems use different actual values for the frequencies (since HF packet is over SSB, you can always tune the rig up or down to line things up) but a very reasonable option is 1600Hz mark and 1800Hz space, which puts the signal right in the center of the audio passband, and is used by Byonics and MFJ TNCs.
