Transmitting Tee Vee From A Pi

Want to set up your own television station? This hack might help: [Jan Panteltje] has worked out how to turn a Raspberry Pi into a DVB-S transmitter. DVB-S is a TV transmission standard originally created for satellite broadcasts, but Hams also use it to send video on the amateur bands. What [Jan] did was to use software on the Pi to encode the video into the transport stream, which is then fed out to the home-made transmitter that modulates the data into a DVB-S signal. [Jan] has successfully tested the system with a direct connection, feeding the output of the transmitter into a DVB-S decoder card that could read the data and decode the video signal. To create a real broadcast signal, the next step would be to feed the output of the signal into an amplifier and larger transmitter that broadcast the signal.

That’s a big step, though, and I hope that [Jan] holds off and does a bit more documentation first. At the moment, the schematics for this are all hand-drawn, and the prototype is a wire-wrapped bit of protoboard. This is a very impressive hack, though: there are amateur DVB-S transmitters available, but most put the encoding onto a dedicated chip. We’ve seen hacks using the simpler DVB-T standard and a Pi before, but getting a Pi to do some of the heavy lifting makes it cheaper and more flexible, so kudos to [Jan] and colleagues for their work.

cabling

24 thoughts on “Transmitting Tee Vee From A Pi

  1. Might be possible to get the Pi to transmit an old style NTSC signal to a low frequency channel like channel 2 without external hardware? I know it can xmit rf at those frequencies… some software, a bit of wire for an antenna and perhaps a bit of smoothing of the harsh square wave signal….

    1. DVB-S signals are transmittet by the satellite at above 10GHz.
      The LNB is responsible for shifting down these signals to less than 2.4GHz so that it can travel through a cable without too much cable loss.

      What he has made can be plugged directly into the receiver, no LNB needed.
      You just need to account the amount the the LNB down shifts the signal (the L.O frequency) when configuring the receiver.

  2. so its 2 fifos in series to smooth any jitter from linux bitbanging GPIO, nice solution
    then 74153 demultiplexer + CD 4040 realizing a double 4 bit serializer, again pretty cool
    finally digitial I and Q are mixed together using 100MHz oscillator divided by 4 = they are shifter by 90 degrees
    after that its filtered and mixed with proper carrier

    I appreciate him using old old school components, whole thing could fit in a 10 year old $2 CPLD, but this way its easier to understand whats going on by just looking at the schematic

    I think Pees DPI (digital parallel video output) could be used in combination with http://bellard.org/dvbt/ as another way of achieving same goal.

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