Virtual radar - Raspberry Pi and RTL-SDR

As you probably know it's been over a year since Raspberry Pi hit the market. Mine spent most of that year in the drawer, so I decided to see if I can use it as low power server for a particular task. One of the ideas I had for a long time was to build a virtual radar type system that would allow me to see airplanes that fly over my area. There are purpose built systems that are quite expensive so why not to do it on a budget and have some fun with it?

ADS-B Basics

Automatic dependent surveillance-broadcast (ADS-B) is a cooperative surveillance technology for tracking aircraft. --Wikipedia

This is one of the ways in which the airplanes report their basic flight parameters (identification, current position, altitude, speed, etc) to the Air Traffic Control. All of this happens over radio broadcasts (completely public) at 1090MHz - at lest this is the frequency we are interested in. The full Wikipedia article is quite interesting and contains more information.

Why bother?

 

If you have ever seen the flightradar24 website before, you have possibly thought (I know I did) about how cool would it be to do it yourself - own one of those virtual radars and maybe even feed the data into flightradar24 to improve their coverage (and get premium account for free)? If you like this idea, you will like the results your own radar station will produce - in general it would be something like this

All of that is easy to build and the cost is really minimal, using either a PC or a Raspberry Pi as I describe in this post.