Feed UAT (978 MHz)

UAT (Universal Access Transceiver) is the second ADS-B datalink, used only in the United States. Light general-aviation aircraft flying below 18,000 ft (18,000 ft is where airliners and most jets, which use 1090 MHz, take over) can choose either; many choose UAT because it also lets them receive weather and traffic information in the cockpit. In Arkansas that means many of the small planes you would otherwise never see.

It is a different frequency, so your 1090 MHz receiver cannot hear it. To contribute UAT you need:

• a second USB radio (RTL-SDR dongles work), with its serial number set to 00000978 so the two radios can tell each other apart;
• a 978 MHz antenna (it can be a short, simple one; 1090 MHz antennas are the wrong length);
• the dump978 container, which decodes 978 MHz and hands the result to your ultrafeeder.

Nothing extra is sent to us. Once your ultrafeeder reads the dump978 container, the 978 MHz aircraft are merged into your normal feed, so the same line you already use carries them. They appear on the map as ADS-R/UAT. If you do not have a 978 MHz receiver you lose nothing: the network still shows UAT aircraft heard by the stations that do.