Heath/FX.25
While discussing internet access via HF Packet Radio on the forums, we discovered this...
FX.25 Forward Error Correction Extension to AX.25 Link Protocol (PDF)
How It Works
It takes an AX.25 packet and adds forward error correction to it. The resultant packet doesn't confuse the far end as it has been designed to be compatible with AX.25. After the FX.25 has been decoded, it is passed to the FX.25 decoder which turns it to an AX.25 packet.
This is slightly counter intuitive because you'd think it would be like this...
AX.25 <-> FX.25 <-> Radio <-> Radio <-> FX.25 <-> AX.25
But it is actually like this...
AX.25 <-> FX.25 <-> Radio <-> Radio <-> AX.25 <-> FX.25
This extension make HF Packet Radio A LOT more useful.
Hacking
It doesn't look that hard as the protocol has a really clever design. There are a few problems though:
- Hasn't been implemented on Linux
- All the parameters seem to be hardcoded
Source Code:
I think the relevant code that needs to be hacked is this: net-tools
ax25.c seems simple enough. I think testing is going to be harder than the coding.
