ADSB.im

Automatic Dependent Surveillance-Broadcast (ADS-B) is an advanced radio technology that combines an aircraft's positioning source, aircraft avionics, and a ground infrastructure to create a accurate data on aircraft movement all over the globe. ADS-B Out works by broadcasting information about an aircraft's GPS location, altitude, ground speed and other data to ground stations and other aircraft, once per second.

The ADS-B signal is unencrypted and easy to receive and decode - and over the last few years a thriving community of aircraft enthusiasts has developed that together track air traffic around the world. There are a number of commercial services in this space (like FlightAware, FlightRadar, RadarBox, and several others) that collect this free data and then sell it to companies and consumers as a services. And there are a number of community supported sites that collect the data and make it freely available to others for research or simply to enjoy knowing who's up in the air above us.

If you participate collecting data and send it to one or more of the aggregators, they generally integrate it into their live maps and make it available for others to see. Some of them (like https://adsb.lol) make it available under an open data license for everyone to work on, analyze and use. This is done in a privacy respecting manner; no one has specific access to your location or any identifiable data about your site.

This is a fairly nice indoor setup - about 5.5 x 3 in in footprint and about 9in tall. It tends to fit nicely on a window sill - but also works well in an attic.

This is a typical outdoor setup - a weatherproof box that's about 7 x 7 x 4 in and a 24 in outdoor antenna that would ideally be mounted outside as high up as possible. That could be on a mast somewhere, on top of the roof, or mounted to an outside wall.

Other than this, all you need is a software stack (you get that from adsb.im) that goes on a small µSD card, a power supply, and an internet connection.

If you got to this page because Dirk is trying to talk you into hosting such a feeder, you can assume that he will provide you with all of the hardware needed and will happily remotely manage the feeder as well. All you provide is a place to put the feeder, power (think ~2W, or something like 50Wh a day or 10-15kWh a year, depending on electricity cost were you are this will likely create a fairly small ongoing cost - something like a couple of dollars a year), and internet access (depending on how much airtraffic can be found above you this typically adds up to a few GB a month - not noticeable in a typical home internet connection).

A lot more information can be found on the other pages of this site - but only worry about this if you would like to get more involved, build your own feeder and manage things yourself.