Sound Modem

Name

SOUNDMODEM.

Description

XRPi does not directly support "soundcard packet", but can interface to existing software such as "soundmodem", written by Thomas Sailer. The setup procedure is described below:

First plug a sound dongle into your Rasberry PI.
Open a terminal and type the following:
```
  sudo modprobe snd-usb-audio
```
Next, obtain the software from a repository:
```
  sudo apt-get install soundmodem
```
Then start the "Soundmodem Configurator":
```
  sudo soundmodemconfig
```
Select File->New->Configuration
Enter a name for the new configuration, then press OK.
Now the tricky part... Click on the name of the new config, and select a mode, in this case ALSA:

Select "half duplex" and "mono" for the capture channel. For "PTT driver" you have the choice of "none" (i.e. use VOX), serial or parallel ports, or CM108 HID interface.
If you chose "soundcard" instead of "alsa", you get a different screen like this:
Create a new channel using File->New->Channel then click on "Channel 0"...
On the "Modulator" tab, select "afsk". The tones for 1200 baud packet are 1200 and 2200Hz. Use the same settings on the "Demodulator" tab.
On the "Packet IO" tab, select mode "KISS" and a name for your soundmodem device. This is the name which XRPi will attach to.
Close the Soundmodem Configurator, then start the soundmodem program:
```
  sudo soundmodem
```

Add an INTERFACE and PORT to XROUTER.CFG as follows:

  INTERFACE=1
	ID=Soundmodem KISS
	TYPE=ASYNC
	COM=/dev/soundmodem0
	SPEED=1200
	PROTOCOL=KISS
	MTU=256
  ENDINTERFACE


  PORT=1
	ID=SoundModem channel A
	INTERFACENUM=1
  ENDPORT

The interface and port numbers aren't important, providing INTERFACENUM matches the number you choose for the interface.

Finally, start XRPi. Remember, the soundmodem must be running before you start XRPi, or else it won't find the soundmodem0 device.

Caveats

The above instructions are only meant as a rough guide, and may not work for you. The exact method may depend on the makes and models of soundcard and computer. In some cases "soundcard" mode will work, in others you may have to use ALSA. You may have to use "modprobe snd-pcm-oss" instead of "modprobe snd-usb-audio".

See also

XROUTER.CFG(8)	-- Main Configuration File
KISS	-- KISS Interfacing