dump1090 is probably the goto solution for receiving ADS-B transponder signals from planes flying overhead because
a) it runs with a cheap rtlsdr USB dongle (more info on dongles here)
b) runs on a cheap $35 Raspberry Pi
I’ve always wondered how it would be possible to get data out of dump1090 to use within other apps. It provides a data feed on port 30003 that is relatively easy to capture by using a util like netcat. If you have another app to receive/parse/process the data, this is as easy as:
nc ip-of-pi 30003 | app-to-parse-data
I have a project ‘in-flight’ right now using this approach… more updates later.