Following up on my not too successful first contact with the Cubieboard, I have decided to try it one more time. It has been annoying me to have a computer board lying on the shelf not doing anything and since I wanted to migrate my Linux-based Funcube telemetry decoder from a PC to a single board computer this was an excellent opportunity / excuse to try the Cubieboard again.
About a year ago I wrote about my modified fcdcontrol application that could be used with the Funcube Dongle Pro and Pro+. The news back then was that it could be used on the Raspberry Pi to control the FCD instead of the continuously failing attempts at running qthid. Unfortunately, the fcdcontrol application often crashed due to a problem at the hidapi / libusb layer.
For some time now I have been in great need of small and cheap AIS receivers that could be used for guiding various tracking equipment during Copenhagen Suborbitals missions. AIS stands for Automatic Identification System and is used by maritime vessels for reporting various status, including position, heading and speed.
About a year ago I posted a step-by-step guide about how to receive NOAA APT weather satellite images using Gqrx SDR and the Funcube Dongle. Today, I tried to repeat the procedure using my ezcap eztv666 rtlsdr dongle with very good results.
Support for RTL2832U-based DVB-T devices is available via the rtl-sdr and gr-osmosdr libraries. This also provides support for Ettus Research USRP’s if the gr-uhd package has been installed prior to compiling gr-osmosdr. A complete build from scratch that would support all hardware devices would thus include the following steps:
I don’t think I ever posted a video showing the built-in AFSK1200 demodulator and decoder in Gqrx, so here it is. The video show local APRS traffic in Copenhagen on a Sunday afternoon. I also tried to receive from the ISS but nothing heard this time.
Here is a short demo showing how to receive broadcast FM with Gqrx. This demo uses the Funcube Dongle, which is really not suited for broadcast FM reception. Gqrx does not employ any tricks to make it sound like it works properly – it just does straightforward FM demodulation with wide FM parameters and you will hear the lack of sufficient bandwidth as distortion on some stations (not all though).
I am happy to inform all users of the Funcube Dongle and GNU Radio, that the gr-fcd driver is now included in the GNU Radio source tree. You can read the announcement here.
This change will be available in the next GNU Radio release, which I think will be 3.5.3, however, if you pull the code from the GNU Radio git repository the changes are already in your tree. Before you upgrade please remove any earlier installations of gr-fcd to avoid conflicting versions of the library.
My repository on Github will no longer be maintained and any future development of gr-fcd will be done within the scope of the GNU Radio project. I hope this will ensure better integration, more maintainers, more testing and easier installation process.
One of the great advantages of software defined radio receivers is that tuning receiver settings is a matter of adjusting software parameters. Gqrx is no different here and has optimal settings built in for weather satellite reception. This tutorial describes how to receive automatic picture transmissions (APT) from NOAA weather satellites using Gqrx SDR, record them to a WAV file, and finally decode the images using the free and open source Atpdec decoder. If you follow this guide you can end up with very nice results such as the one shown at the end.