HF Packet

I thought that I would share some findings in relation to HF Packet, after some recent exploration.  Firstly the Sound Modem developed by Andrei UZ7HO is a great piece of software, with recent improvements added towards the end of last year.  These include CAT control for PTT and also support for USB CN108 devices (Commonly used in VOIP setups).  I'm using the CAT PTT with my IC-7300, and it just works!

You can also run two modems within the audio bandwidth of you transceiver. So if you wanted to run APRS on the frequency allocated you can do that and then run a second modem on a frequency, say 800Hz down the band. This could be used for connecting to a BBS, mailbox or general chat in terminal mode or even a game of Chess.

I have included some screen shots of my settings.

You can see that the two modems are centered on 900Hz and 1700Hz.

Dual channel is active, TX rotation means that only one modem will TX at a time. and the third setting directs both modems to the one sound device.  Note also the PTT Port is set to CAT.

 

On HF in SSB mode it doesn't take much to be a little off frequency, and therefore render communications ineffective.  By adding additional RX pairs, at a spacing of 30Hz either side of the set frequency, allows a station that is 60 or 70Hz off frequency to still be decoded.

There is still some exploring required, but this is a good start!