[Xastir] Soundmodem

[Andrew Errington]

On Sun, 08 May 2011 10:24:06 Jarett DeAngelis wrote:
> Curious -- what's the use case here?  Are you running on 2m and 70cm?

Um, no.  Nothing so exciting.  I am just testing.  I am modifying soundmodem 
to include PTT control via GPIO on the USB sound chip (I talked about this on 
this list recently).  I need to test soundmodem to make sure I didn't break 
anything.  I only have one radio, and I don't know enough people in this area 
who would volunteer to be the 'other end' yet.

For testing, I wanted to be able to send on one modem and receive on the 
other.  Since I have only one radio I'm not actually using any radios.  
modem0 has a speaker attached to the soundcard output, and modem1 has a 
microphone attached to soundcard input.  I could wire them together, but I 
wanted the illusion of over-the-air comms. :)

soundmodem will work in duplex mode, so it can send and receive at the same 
time.  It seems that it doesn't matter that Xastir sends my test message to 
both modems, since I can receive the test message from modem0 on modem1 even 
while modem1 is transmitting.  I suppose I could run two X sessions and run 
Xastir on each one.  I could send a message from one instance and receive it 
on the other.

Since it works I can now take my PC (laptop), two USB soundcards, one radio 
and one microphone to the local hams and demonstrate.  I can show APRS 
messaging by holding the mic. next to someone else's radio, which means I 
don't run any risk of damaging their hardware.  APRS is not really popular 
here, which means it might be completely new to some people.

73,

A