Some time ago, I read a thread on Reddit called “What are some great subreddits whose names cannot be found by searching their subject matter, making them hard to find on search?”. Other than being a fucking long title, it was also pretty interesting. What really piqued my interests was this post about RTLSDR, which essentially boils down to a cheap USB tuner that can catch all kinds of signals.
I looked around on the internet, read some reviews and bought a quite okay dongle for around 150 kr. Cheap enough for me to check out it it’s interesting and not so expensive that I cry myself to sleep if it’s not something for me.
After a week or so, I received my dongle. The build quality is quite nice and the antennas seem of decent quality. The software itself was quite easy to setup and in around 10 minutes I was listening to FM radio. P3, P4, The Voice, Radio Nova and so on. Nice, but not that interesting.
ADS-B
Having figured out how to listen to normal radio, I went deeper down the rabbit hole. I looked around the internet for tutorials on other stuff to do, and found out you can listen to ADS-B. Or Automatic Dependent Surveillance – Broadcast as it is called. That is the system in which aircraft determine their position by GPS and broadcasts it, enabling them to be tracked. As I live in Aalborg, there is an airport not far from town.
I found out I need two programs. One to catch the ADS-B signal and another to show me the trackings on a map.
First I started out with the program to catch the signal. I found one called RTL1090. Getting that to work, proved quite difficult. The program installed fine, but the drivers didn’t work. All in all I had to look through 4 or 5 different versions of the program (which aren’t easily found), before I managed to find a version with the right drivers.
With that installed, I installed a program called adsbSCOPE. You load up a map / portion of the world and then it speaks with RTL1090. That means that all the data and trackings pass from one program to the other and the data is translated to visual trackings. In other words, I can see the planes on a map like with an aircraft radar.
adsbSCOPE with RTL1090 tracking two aircraft from Aalborg
This is all with a stock setup. It is however possible to get better results (read: longer range and/or clearer signals), but for that you need a certain kind of antennae. It turns out, there is different types of antennas for different kinds of signals. Who would have guessed.
So for this, one type of antennae might suffice. Were I for example to pull down images from a weather satellite, I would need another kind of antennae. Were I to listen to the Voyage space probe, I would need something totally different.
What’s next?
This turned out to be quite interesting and somewhat easy to get up, once I managed to get hold of the correct drivers. Next up I’m going to try and see if I can get a good enough signal from a weather satellite and get some images from that. How I’m going to do that, I don’t know yet. But I’m going to find out.