In the last days, i tinkered with different things: I installed Docker onto a Raspberry Pi 2, built several docker images [1][2] and got myself two new RTL-SDR-Sticks.

Today, I’ll bring all these Projects together and show you how to build a virtual aircraft radar (screenshot) – so fasten your seatbelt 😉

I’m ready – tell me what I need

• You’ll need a Raspberry Pi 2  – yes, 2! – Of course, you can go with a Pi 1 – but to be honest, this thingy has just not enough ram and only one core so it’s not really suitable for docker. But hey, if you like the pain – go on 😉
• The Pi has to be prepared to run Docker – You can use the guide from my blog post if you need help
• And of course you need a RTL-SDR Stick – so if you ever watched DVB-T on your Laptop, the chances are good that you already have a suitable Receiver. Some people over at Reddit compiled a nice list of sticks which are suitable for our little experiment. Oh, and an Antenna would be awesome 😉

List completed? All points checked? Great, let’s go on!

Got my stuff together – Can we build the container now?

Well, – no! We have to prepare our system first in order to use the RTL-SDR for our experiments. Unfortunately, the most operations systems have the behavior to load own drivers for specific hardware. This also happens for our RTL-SDR (DVB-T) Stick, To prevent this, we have to blacklist the system drivers.

So please connect to your raspberry via SSH and run the following command:

This will blacklist the default drivers and prevent the system to load these.

Now reboot your raspberry and reconnect via SSH.

Ok, now we should check if the raspberry is able to find the RTL-SDR Stick. So plug it in and run the command  lsusb . You should get an reply like this

The last three lines are internal USB devices of the Raspberry itself (yeah, the NIC is a USB device – weird eh? 😉 ), but the first entry in the list is the RTL-SDR Stick. It is possible that you see a different name, but it should always have the RTL in its name.

Ok, you see the stick in the listing? Cool, proceed!

I’m prepared – can we start now?

YES! Let’s go! We will now build two docker containers – the first container will be our “Baseimage” which contains the RTL-SDR library (which is utilised by all the other SDR tools) and the final DUMP1090 container which contains the app itself.

Part 1: the Baseimage

Connect again via SSH to your raspberry. Add a new directory called “Baseimage” and add a file called “Dockerimage”

Edit the “Dockerfile” (either using vi oder nano, your choice) and add the following content

Now you can build the Baseimage. Run  docker build --rm -t rtlsdr-baseimage .

This will build a container called “rtlsdr-baseimage”. Docker will now download the Debian container (~150MB), install the compiler toolchain and build the RTL-SDR tools. Take a break and let the Pi do the work 😉

Oh, if you don’t want to build the image yourself, you can use my prebuild container – sysrun/rpi-rtl-sdr-base

Build done? Let’s check if the container is really there – execute a quick  docker images | grep baseimage . That should give you the following output

Baseimage is there? Good – now go on

Part 2: the DUMP1090 Container

The next steps are basically the same as for the Baseimage. Add a directory and add a Dockerfile

Again edit the Dockerfile and add the content below

And build the container via  docker build --rm -t dump1090 . It’s now using our Baseimage, pulls the DUMP1090 sources from Github and compiles it. The whole process takes about 5-7 Minutes – so feel free to grab another coffee 🙂

Looks good? Awesome!

My Containers are done – Aircrafts please!

Yeah, easy! So let’s just start our Container and see how it works. We’re exposing port 8080 from our Container to our host system (-p 8080:8080) and starting dump1090 with the –interactive and –net option to enable the web interface. After the start you will be able to access the web interface by opening the url http://<yourpiip>:8080

Run  docker run -it -p 8080:8080 dump1090 --interactive --net  and let the magic happen.

HUH? WTF?! But you told me everything is in place?!

Yeah, everything is in place – but it’s not accessible by our container! Every container runs in an isolated context. That means that the container has no access to the host machine or to other containers by default. No access to the hard disks, keyboard, mouse, graphics… and, of course, no access to the usb devices…

Now there are two ways to fix this issue:

• Using –privileged: this will run the Container in privileged mode. That means that the container has basically complete access to the underlying hardware of the host.
• Using –device=/dev/bus/usb: This is the better options as we’re not exposing the whole host to our container but only the usb devices.

So let’s run it again:  docker run -it --device=/dev/bus/usb -p 8080:8080 dump1090 --interactive --net

Awesome! 🙂

Now fire up your browser and connect to the web interface. If you place the antenna at an unobstructed place near the window, it should start showing airplanes after some seconds.

There will be several follow-up blog posts on this topic – showing you how to receive Ships and Text-Messages from Airplanes, so stay tuned 8)

If you have questions, just drop me a line via twitter or in the comments 🙂