ADS-B (Automatic Dependent Surveillance–Broadcast) is the system commercial aircraft use to broadcast their position, altitude, speed, and identity. Every plane overhead is transmitting on 1090 MHz. A $25 RTL-SDR dongle can receive it.
The project started as a curiosity — can I track planes from my apartment? It turned into a deeper exploration of how the aviation data infrastructure actually works: the difference between Mode S and ADS-B, how MLAT works for planes that don't broadcast position, how FlightAware and FlightRadar24 aggregate feeds from thousands of receivers.
"The interesting part isn't the hardware. It's realizing that the entire global aviation picture is assembled from thousands of hobbyists running $25 dongles out of their windows."
The build: RTL-SDR dongle → dump1090 decoder → Python feed processor → live map overlay. The data pipeline runs continuously, feeding into a local PostGIS store for historical analysis.