Monday, 19 November 2012

DATV-Express Video

This is a video I made showing the prototype DATV-Express hardware / software.
The next version of the board should be out in January, after I get version 2 to work
I will post a more comprehensive video.

If I had know how much effort there was in getting this video imported into my PC
I probably would not have bothered.

Update 24th Nov: rev2 has passed its final design review so it is on schedule for January.


  1. Thanks for the informative video very interesting. So looking forward to getting hold of one and getting some activity going. This is even more important as you previously mention the vultures circling after our spectrum. All the best. Ian G8XZD.

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  3. Things should progress quite quickly once
    the rev2 boards are done. The main
    difference is the rev2 board is slightly
    smaller in size, has extended frequency
    range and a dual channel A/D converter
    for self calibration and VSWR measurement.
    We are making the internal LO output
    available (whis is at the operating
    frequency) for expansion possibilities.
    The spare FPGA pins will be available
    for a high speed interface either to
    connect boards together or multiple
    boards to a much larger FPGA for stand
    alone operation (in a repeater for example).
    (corrected version)!

  4. Hello Charles,

    Thanks for the video, looking forward to the release!

    You have mentioned the Raspbery Pi before, any chance of that working as the "PC" portion of the system?

    Mike KM7MH

  5. Thanks Mike,

    Maybe, there are some issues with the RPI
    1) It does not have MPEG2 hardware encoding
    2) It is not fast enough to do the DVB-S/S2 encoding
    so that would need to be done on the FPGA which is only big enough to handle DVB-S.
    So if you are happy with DVB-S and MPEG4 it should work fine most HD satellite receivers can decode that combination.
    It also all depends on what device drives are supported by the PI. I noticed the development people are starting to add various DVB receiver devices. I am rather loathed to port kernel device drivers myself! So it may well happen
    - Charles G4GUO

  6. Would be nice to shrink the hardware down so it could be placed in a RC model aircraft.

    I worked on an IP video design several years ago that used the now obsolete Conexant CX23416 ASIC MPEG2 encoder. Do you have any experience with FPGA based MPEG2. An MPEG2 daughter board with onboard flash for the encoder as well as modulator would be great for this sort of application.

    Mike KM7MH

  7. Well I think that is a step too far at the moment.

    No I am not familiar with that encoder. The sooner we drop MPEG2 the better as far as I am concerned. HVEC will be the way to go when the chips are available as that will be twice as efficient as H.264 but that is a few years off yet.

  8. It will be a fun challenge seeing how compact the present system can be made. May be able to fit it into a larger RC model.

    The effort you guys have put into this project is greatly appreciated!

    Mike KM7MH

  9. Charles, I'm looking forward to a future acquisition and running of this unit to make some amateur radio digital television. I already have my encoder/decoder, power amps, pre amps etc. Keep up the great work! KD6W

  10. Things are moving along, the rev2 board is being laid out now so I should be able to port the current code over to the new board early in the new year. Then start working on the enhancements. Hopefully the new board will be good enough for final production so we can get stuff out there.

    - Charles

  11. How did you get on with that 1.5G spectrum analyser you mentioned on Twitter? Would be interested to know. 73. Ian

  12. Hello Ian, Yes it works well. I used it to align a couple of 435 MHz bandpass filters. Today I used it with a mixer and a 9GHz YIG oscillator to translate the tracking oscillator up to 10 GHz so I can use it to align some 10 GHz bandpass filters. I need a second mixer to mix down to 1 GHz again of course. It should be possible to translate up/down for most bands. There are quite a few reviews of the Rigol DSA815T on YouTube if you are interested. I have not tried the PC software yet or tried printing yet. It is solidly built nice and portable (unlike my HP machine) and not bad for the price. As it operate up to 1.5 Ghz it should be possible to use LNBs (like C band for 3.4 Ghz) to extend its range, i.e use it a a tunable IF.

  13. Thanks for that Charles - looks a very interesting piece of kit - I can see many ham applications for it and it would make a lot of routine tweaks a lot easier - he said looking at a 23cm interdigital filter that needs aligning - Have been reading what's on the 'net - especially the comparison with the Signal Hound. Although I like the fact the SH goes up much higher in frequency the Rigol looks more business like. Certainly it has raised a lot of debate. 73 for now have a happy Christmas - looking forward to the new year and datv express.