I recently built a usb soundcard with push-to-talk functionality, which is perfect for interfacing the Baofeng UV-5R to the PC and sending APRS over it. It is quite simple to set-up and works well.
First clone my fork of direwolf with support of the CM108 soundcard:
git clone https://github.com/donothingloop/direwolf_cm108.git cd direwolf_cm108 make
Open the direwolf.conf file and set the following options:
MYCALL <YOUR CALLSIGN> AGWPORT 8000 KISSPORT 8001 PTT CM108
Then install xastir.
For Ubuntu, Raspbian, Debian enter:
apt-get update apt-get install xastir
After the installation has completed, start xastir. You should get a window looking like this:
Click on Interface and then on Interface Control.
In the following dialog click Add.
Select Networked AGWPE and click on Add.
Check if the port is 8000 and change your Digipeater paths according to your country’s requirements. Then click on OK.
You can now try to transmit. Set your radio to your local APRS frequency, click on Interface and then on Transmit Now!.
The red led of your soundcard should turn on and your radio should start transmitting.