And if anyone wants to help contribute data, there are a few ways to get started.

1. The minimal: Raspberry Pi and an RTL-SDR dongle. You can even use the small stock antenna that often comes with a dongle, if you put it near a window.

2. A real 1090 MHz antenna, plus filter + amp will greatly increase your performance, and cost less than $100.

Weidehopf has a shopping list: https://github.com/wiedehopf/adsb-wiki/wiki/adsb-receiver-sh...

As does flightaware: https://flightaware.com/adsb/piaware/build

Software-wise, you have a couple nearly-turnkey solutions. The easiest thing is just to follow the guide at https://www.adsbexchange.com/how-to-feed/ You can even use their custom Raspberry Pi image, and instantly have dashboards and maps and all the cool stuff.