I wonder, how the feeder hardware get data, signal about flights, from what source, how they "see" airplanes and their live flight routes ?
https://mode-s.org/decode/ Flight plans / routes are not broadcast via 1090 MHz .... 1090 MHz is the downlink for ModeS secondary radar. On the same band there is also extra ADS-B broadcast, position and other messages from aircraft that don't require interrogation. About secondary radar and the modulation used for ModeS / ADS-B: https://www.radartutorial.eu/13.ssr/sr04.en.html
