The Pi plus a USB soundcard is all you need to get started with Packet Radio. Instead of using a dedicated hardware TNC, the Pi can be coaxed to do the hard work of managing the Packet protocol.
Full instructions can be found on the WB2OSZ’z website at: https://github.com/wb2osz/direwolf
Start with the latest version of Raspbian Stretch and update it as follows
(Open the terminal and enter the following commands):
sudo apt -y update && sudo apt -y upgrade
The only additional package required is libasound2-dev so install that as follows:
sudo apt install -y libasound2-dev
Now we can install Dire Wolf as follows:
git clone https://github.com/wb2osz/direwolf
sudo make install
Now we need to make a couple of changes to the configuration file:
sudo nano direwolf.conf
Scroll down to the line: #ADEVICE – plughw:1,0 and delete the # from the start of both lines.
Scroll down to CHANNEL 0 PROPERTIES and replace NOCALL with your callsign-1, i.e. G4WNC-1. NB: This must be caps.
Press Ctl x followed by y to save and close the file.
Reboot the Pi and run Dire Wolf by double-clicking on the desktop icon.
If you want an APRS client for the Pi then YAAC works well.
You can also add a USB GPS or a GPS Hat to make the Pi into an APRS tracker. Details are on the WB2OSZ website.
For more information have also a look to G4WNC’s homepage. There you can buy a ready made SD Card.