We had those kinds of encrypted transmissions in Sweden too. Large corporations, for instance, would broadcast board meetings or some important event to their regional offices. Since Swedish Television (SVT) was far from 24/7 there was plenty of unused capacity available on the transmitter network.
@@memediatekI'll see what I can do. My father recorded "A Fist Full of Dynamite" (the movie at the end of this clip) and must have left the VCR running. Furthermore, I've checked this date on BBC Genome and the last transmission (BBC 2) is 02:00; weather. BBC beyond that, nothing is mentioned about any further overnight transmissions. In the days of BBC Select (1992-95) it would have been mentioned in the Radio Times. 📺
Even though the main BBC2 logo, clock, programme slides and programme slides used the stencilled TWO typeface Test Card F on the channel still used the 1979 to 1986 channel identity typeface for legible reasons.
I think the jittery footage at the end, is Sound-in-Syncs. It looks like a test tx because mixing the audio in with the picture would mean that the BBC could ditch 1000s of BT / Post Office audio circuits, because sound and vision were combined into the one PAL signal. The BBC received a Queen's Award in 1978 for its contributions to multiplexing sound and video signals. Or it could be a fault!!
It's deliberate picture scrambling, using three levels of delay. It proved to cause problems if the picture had ghosting (multipath) and they switched to using line swapping instead when BBC Select launched. The sound scrambling system used was spectrum inversion.
You may have noticed from watching testcard videos from around this period, that BBC1 always used a higher test tone to BBC2 - this would have been a useful way for engineers to identify the channel if they had no corresponding picture to refer to. Much how different ITV regions used different test tones.
I did once read an article about it, but I would imagine that the sound compression methods used by RU-vid have probably mangled the sound to a point where it might not be decodable. But in theory, I do believe it's possible
Like I say @@dylaninpieces2 I did read about it a long time ago - I should imagine it's possible to emulate the hardware decompressors of 30 years ago in software, but whether the signal would be readable is debatable. I don't think there's anything to be gleaned from decoding this but if you ever work it out I'd love to see the results!
