This weekend I have been playing with a full duplex transceiver version of the simple DVB setup that allows to use only one computer and one USRP as a transmitter and receiver. By using separate daughterboards I can use one side to transmit and the other side to receive. Using two sets and two frequencies the transceiver can be used for two-way video conferencing over the air 🙂
The transceiver is pretty much the same as the transmitter and receiver I wrote about earlier, but now they are in one flow graph.
Here is a short demo video showing the setup in action. Sorry for the bad quality, I only had a pocket camera with me
This was also a good exercise to see how much computing power all this needs. I used a 13″ 2.4 GHz MacBook Pro and it did quite well at 50-60% CPU load on both cores. Quite impressive, although it was still just 640×360 and not HD!
I have let the setup run for more than 4.5 hours and it was very stable. I even played with the gain settings and introduced interference to break the RF link. Every time it could re-sync without problems.
The GRC files are now available from Github, see http://github.com/csete/gnuradio-dvb – to check out a read only copy use
git clone http://github.com/csete/gnuradio-dvb.git
git clone git://github.com/csete/gnuradio-dvb.git
I have also created a Wiki page for these experiments.