Configuring ADS-B Ports

YAAC's adsbdecoder plugin can receive ADS-B and UAT aviation surveillance radio signals using Software Defined Radios (SDR) and appropriate demodulation software, such as the rtl_sdr software package with its rtl_adsb decoder program, or optional software that can decode and convert UAT information, such as available at https://github.com/mutability/dump978.

To add a new ADS-B port, click the Add button on the Configure Ports tab. The port editing dialog will appear. Set the port type to ADS-B.

The other parameters you will need to specify for ADS-B is the connection to the ADS-B receiver you will use. The ADS-B receiver must provide the demodulated ADS-B raw information in the format

*xxxxxxxxxxxxxxxxxxxxxxxxxxx;

where the * and ; are literal characters and the x characters are the hex digits of the binary message (the Linux utility rtl_adsb reports the messages in this format). YAAC can connect to the ADS-B receiver in two ways:

• Command mode: In this mode, YAAC launches a program or command as a sub-process of the YAAC process, and listens to the text written to the standard output file of the program or command for the ADS-B frames. Typically, this will be something like:
  rtl_adsb
  (assuming you have this program installed and on your current path), or possibly a more complex piped command, like this one for processing UAT transmissions:
  rtl_sdr -f 978000000 -s 2083334 - | dump978 | uat2esnt
  Note that these commands must be executable in the context that YAAC is running in, so, depending on how you installed the SDR software and set up your path, you may need to specify where the programs are located explicitly.
• Socket mode: In this mode, YAAC makes a TCP socket connection to the specified Internet host computer TCP port number, and expects to receive the ASCII-hex frames from that socket connection. For example, the dump1090 program has the option --net-ro-port to make this data format available on port 30002.

Because aircraft move much faster than normal APRS targets, the ADS-B plugin uses a different timer for expiring ADS-B targets with a shorter range of values.

Once you have the settings the way you want them, click OK. Ensure that the SDR is connected to your computer, if you are using socket mode, that the SDR software has been already been started on your computer before you click OK. At that time, the port will launch the specified command (if using command mode) or connect to the SDR software socket (if using socket mode), and wait for ADS-B ASCII-hex frames to be received.