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I have now tried the USRP on Mac OS X using the MacPorts installation and I am happy to report that it works very well. Indeed, the USRP is really plug and play on OS X and there is no need to configure udev or anything like it is the case on e.g. Ubuntu Linux. The video below shows the FM receiver listening on the local APRS frequency.

Few days ago Michael Dickens announced that the GNU Radio packages on MacPorts have now been updated to 3.3.0 and so I took this opportunity to try it. I didn't have MacPorts installed so I had to start from scratch; however, installation was quite straightforward because the dependencies are resolved automatically. All I had to do was to download the latest MacPorts dmg and then execute the command

  sudo port install gnuradio

then let it run overnight. It takes a long time since MacPorts builds everything from source. On my iMac it took more than 6 hours. Note that gnuradio is a meta packages that depends on all GNU Radio components.

Few weeks ago I was told about an opportunity to fly something small on an amateur rocket in October, when the guys from Danish Space Challenge will launch a bunch of rockets. I figured it was a good excuse to resume my work with the Gumstix Overo embedded conputer that I have lying around.

Yesterday I have been testing the DVB setup using Theora encoded video in Ogg container instead of the H.264/MPEG-TS I have been using so far. Initial tests looked promising, but at the end the link was rather choppy and broken.

On this first screen shot I am running the simulator (i.e. no USRP) with a test pattern as video source. This setup was very stable and I was surprised to see that mplayer got synced much faster than when using H.264/MPEG-TS.

The second screen shot shows the setup running with the GMSK transceiver and again using a video test pattern as source. I have let it run for over 2 hours during which it was very stable. Of course, I was playing with the RF settings while it was running to make it loose the signal and force it to resync – no problems there.

Finally, I replaced the video test pattern with the Logitech Webcam Pro 9000 as video source and this is when things have started to become bad. The video came up all right but already after a few minutes, the playback becomes choppy and mplayer starts spitting "Ogg: bad packet in stream 0" messages out in the console. At the same time, the frame rate drops to about 1 fps. So this is not very useful.

For now, I will stick to H.264/MPEG-TS.

Last week I participated in a small competition held by Google Lunar X Prize team Part Time Scientists and won a t-shirt with their slogan "Hell Yeah, it's rocket science!"