gr-air-modes

gr-air-modes is a GNU Radio-based tool for receiving and processing Mode S/ADS-B radio signals from aircraft transponders. It enables users to capture aircraft position reports and other flight data using software-defined radio hardware.

The tool offers versatile output options suitable for various applications, including raw packet data, human-readable parsed text, SQLite databases for storage, KML files for visualization in Google Earth, SBS-1 format compatible with flight tracking software like PlanePlotter or Virtual Radar Server, and FlightGear multiplayer interface for real-time simulation display.

Primary components include the modes_rx receiver application and the libgnuradio-air-modes library, making it suitable for both standalone signal reception and integration into larger GNU Radio flowgraphs.

gr-air-modes uses GNU Radio to process Mode S transponder signals, including ADS-B extended squitter messages from aircraft. It receives RF signals via SDR sources like UHD (USRP), Osmocom, file input, or UDP streams, demodulates and decodes the Mode S packets, then outputs the parsed aircraft data in multiple formats. The receiver supports GPS location tagging of the station and can merge data from remote TCP sources for enhanced coverage.