History in the making

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  Sid Law Posts: 4,705

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  01/02/15 - 17:33 #2

  FIFA1966 wrote: »

  As I proudly present:
  
  The BBC Selector box:
  
  
  http://downloads.bbc.co.uk/rd/pubs/reports/1995-11.pdf
  
  
  You have to scroll down to see the image.

  
  Wasn't this system similar to the one used by Sky analogue, but the BBC system also scrambled the audio?

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  [Deleted User] Posts: 8,718

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  01/02/15 - 17:59 #3

  Your point is?

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  Steve1977 Posts: 1,274

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  01/02/15 - 19:26 #4

  Unsure what I'm looking at but interesting nonetheless! Was this basically an early attempt at VOD? Very cool it was possible years ago!

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  technologist Posts: 13,383

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  01/02/15 - 19:45 #5

  There was government pressure to use the bbc frequencies (when they were not using them) for commercial uses . This included extra VBI lines that CEEFAX were not using !!!!! Which never happened ... See eng inf 40 http://www.bbceng.info/Eng_Inf/EngInf_40.pdf
  
  And BBC select which provided subscription tv which could be recorded for doctors etc
  Using the early hours of the morning....... There were others professions ... Lawyers I think
  See http://en.m.wikipedia.org/wiki/BBC_Select
  It worked .. But there was not the commercial interest ......
  And like bbc datacast ..... Were taken off analogue before DTT launch as the BBC did not want to be carrying commercial services on a PSB mux ... If only ofcom had the same idea !!!

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  Captain Jack Posts: 35

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  20/01/18 - 18:27 #6

  Hi,
  
  Sorry for digging up a dead thread....
  
  I don't suppose anyone has one of these BBC Selectors? Happy to cover cost of postage and several beer tokens.
  
  Cheers
  CJ

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  Sid Law Posts: 4,705

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  20/01/18 - 21:20 #7

  Don't apologise for digging up an old thread Captain Jack, this stuff is really interesting to techy anoraks.
  
  One thing that interested me 20 years ago and still interests me now is why the pictures were scrambled at all. Surely scrambling the sound would have done the job? If you can't hear the programme, your not likely to watch it?
  
  I can understand why the pictures on (analogue) Sky were scrambled as you can watch a football match without sound......and easily listen to the commentary on the radio, but other than that, pics without sound would be a minority interest.

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  Swebbster Posts: 947

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  20/01/18 - 21:27 edited 20/01/18 - 21:30 #8

  BBC Select Trailer
  https://youtu.be/AZbbFfDaRD0
  
  BBC Select Intro
  https://youtu.be/uisMEnYM2nM
  
  BBC Select Scrambled
  https://youtu.be/HcCdw97_ESA
  
  Scrambled engineering test
  https://youtu.be/89fW2gum-B0

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  Captain Jack Posts: 35

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  20/01/18 - 22:01 #9

  This is a really interesting scrambling method. Also called Videocrypt but the "S" variant (Shuffle?). This is because the standard one (ver 1 or 2) introduced ghosting due to terrestrial signals bouncing. Line shuffling seemed to mitigate this...
  
  I am actually trying to build an encoder for this, hence being on the lookout for the decoder. We've done this for Videocrypt 1 and, to an extent, Nagravision - though no hardware decoding possible at this point.
  
  Some videos that might be of interest. Videocrypt 1 scrambling real time using HackRF and decoding using an old Sky card!
  
  (Posting YouTube video ID as code as the forum isn't letting post live links yet - just search in YouTube for these IDs)
  
  

  YouTube - FgoNPRX53zY
  

  
  Nagravision encoding real time and decoded using "MoreTV" type software:
  

  YouTube - 9fTNe-yQzVQ
  

  
  We are also playing with a D2MAC encoder:
  

  YouTube - U4RoAnvS9zc
  

  
  Trying to revive all that obsolete equipment!
  

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