So finally my Flightradar24 feed is up and I am all very excited. The “radar” is actually a receiver for the open ADS-B signal being transmitted on 1090 MHz. The system consists of a Beaglebone computer in a nice metal case, an external Mode-S omni-directional antenna (55 cm), and a GPS antenna for data timing precision and MLAT (not shown).
I received this system from Flightradar24 and have to feed coverage data to them in exchange for a premium account. It is not open data although the public does get access to the result at flightradar24.com
You can also build your own ADS-B receiver using a Raspberry Pi and a low cost DVB-T USB stick (terrestrial tv receiver). Your receiver will run Flightradar24’s Rasbian-based Pi24 client to track flights within 200-400 miles and will automatically share data with Flightradar24. You can track flights directly off your Pi24 device or via Flightradar24.com
There are some options to keep the data you collect while losing access to the data of other receivers — Planeplotter seems to be the more mature one — but unfortunately none of them seems to be under active development and all are proprietary and most Windows-based.

Basic setup with internal antenna, DVB-T dongle and Raspberry Pi/PC
Reciever Coverage
Based on relief around my receiver in Gjakova, I’m providing good coverage of western Kosovo. My house is situated slightly below the immediate terrain and 60 m below the Gjakova airport runway midpoint 7.5 km to the north, meaning I might not be able to see aircraft on the ground once that airport is operational. I also have high mountains 8-16 km from south-west to north-west and further away facing south. Below is a polar plot of the aircraft being seen, with north to east coverage clearly dominating, also a result of traffic routes.

Rooftop view north-east

View of Gjakova Airport
Gratitude to antenna master Teki Dobroshi for helping with its setup and Yll Ferizi for troubleshooting network cabling problems.
Happy hacking!