Teletext On A Raspberry Pi With Zero Additional Parts #piday #raspberrypi @Raspberry_Pi
Teletext on a RasPi with zero additional parts. via hackaday
Way back in the 70s, the UK and BBC rolled out teletext – an information retrieval service that’s much closer to the ‘television screens connected to computers the size of a room’ popularized by 1960s futurists than the Internet and world wide web. For about 30 years, teletext was one of the most reliable means of information distribution until it was quietly shelved with the rollout of digital television.
Playing with dead protocols is fun, though, and since the Raspberry Pi has an analog video out, [Alistair] thought it would be fun to turn his Pi into a teletext generator and display.
This isn’t [Alistair]’s first teletext rodeo; earlier he built an add-on board for the Raspi that uses an AVR and an LM1881 video sync separator to mux the video output of a Raspi with teletext signals. The new build does away with this completely, allowing any Raspberry Pi to generate and display information from a teletext service. Right now there are two demos, a Raspi status display that shows the CPU frequency, usage, memory, and temperature. There’s also a ‘clock cracker’ with a picture of Tux that should help diagnose reception issues.
All the code is available on the project’s github, although [Alistair] hasn’t released the scripts to output teletext pages captured from broadcast signals years ago.
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To be fair, Teletext isn’t really that dead a protocol. It is true that the UK retired it when it retired analogue TV transmission, as it had introduced more modern digital text standards.
However lots of the rest of Europe simply shifted the same services on to digital platforms (as the BBC did initially with a basic CEEFAX service on satellite). In countries like Norway, Sweden etc. you still get teletext on digital platforms, and often the text service is re-inserted on the analogue outputs of SD satellite receivers to let you use your Teletext decoder in your TV just as when you were watching analogue TV.
This Pi application could be even cooler if you could use a DVB-T/T2 or S/S2 tuner to receive a channel which still carries digital teletext (lots of European channels on Astra 1 at 19.2 will I expect), decode and output the MPEG2 or H264 video AND insert the digitally received teletext PIDs into the analogue VBI as teletext in blanking, like some satellite receivers do.