So you all saw my last posts [ Play with SDR and Intel Edison! QFH Antenna and my first reception of NOAA! ] but I actually didn’t explained how to capture and decode APT Signals using your computer (in this case, with Linux). So here it is! For this article I’m using Ubuntu 15.04, but actually any distro will work well (I think most of them have the needed packages)
So some people already saw in my facebook that I started playing with SDRs (Software Defined Radio).
I always wanted to do my own radio receiver, and I did some in the past. But it’s very hard to adapt the radio for anything new you want do to, and also when you want to process data in your computer things become harder.
So a few months ago I found a nice tutorial of how to get NOAA Satellite Images using a cheap DVB-T (Digital Video Broadcast – Terrestrial) dongle that can be used as SDR. It costs about R$70 (roughly US$10) and the model I got (with R820T2 tuner) can tune from 24MHz to 1.74GHz!!!
What is inside this spectrum?
Actually a lot:
- FM Audio Radio Broadcasts
- VHF / UHF Television (Both Digital and Analog)
- Weather Satellites (APT, LRPT, HRPT)
- ADB-S (Air Traffic Telemetry)
- FM Air Traffic Radio
- And more
So my goal was to receive NOAA APT Signals (I even made a decoder!) but I don’t have a good enough antenna (yet).
So I made up a piece of antenna with two copper pipes (I call a piece, because its a dipole from a Double Cross Antenna) (I will make a tutorial later how to do it) to have better reception for the 2m band (~135Mhz) but every time a satellite was in range, I would need to go outdoor and turn on my laptop and start capturing. This was annoying.