In October last year I learned about the UT-100 series of DVB-T modulators available from a company in Taiwan. At that time I have already been working with software defined video broadcasting; however, I still found the idea of a small USB-stick modulator very appealing for use with embedded devices. In this post I have collected my notes about setting up and testing the UT-100 modulator on Linux.
You may already know about my existing enthusiasm for Logitech webcams, which is due to the combination of relatively good image quality, high resolution and easy to use UVC interface. I was therefore very happy to learn about their newest camera, the HD Pro Webcam C920, which in addition to the standard HD webcam stuff we already know from the C910, also provides hardware encoded H.264 video stream! This is rather new and there isn’t much software that can take advantage of it; however, with a little tweaking and hacking we can get the H.264 stream into Gstreamer, where after we can do pretty much whatever we want.
RTL2832U-based DVB-T dongles are now supported by Gqrx SDR, see this announcement!
You may have noticed the recent buzz on the internet about using cheap DVB-T dongles as software defined radio receivers. It all started on this mailing list when V4L/DVB kernel developer Antti Palosaari discovered that the ezcap EzTV 668 DVB-T/FM/DAB USB dongle, which is based on the RTL2832U chip, can be used to stream raw I/Q samples to the host computer. It is in fact the way the device supports FM and DAB reception; raw I/Q is sent to the host where the application does the demodulation.
I’m happy to report that I am now able to encode video on the Gumstix Overo Water using the DSP in the OMAP3530. It wasn’t difficult to make it work but it took several attempts at building the kernel before I got it right and, as you might know, cross compilation takes time.
As I tweeted last Friday, I managed to get a Funcube Dongle this time! The dongles were packaged over the weekend and shipped Monday this week. I could pick up mine at the local post office earlier today. Initial smoke testing using Linux and GNU Radio has been very encouraging for further experiments.