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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc.

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Old 14th Jan 2019, 2:52 am   #1
Chris55000
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Default TV Transmitter Close Down/Start Up Routines?

Hi!

This refers to the normal daily startup/closedown sequences prior to 24h broadcasting rather than the final analogue TV closure.

I can remember a period of time when BBC2 closed down with a sequence of colour pictures of natural scenes, with music, then a closedown announcement, then sometimes a very short period of TCF with interspered music/tone, then the card faded out to a dark (often greenish) unmodulated synchronised raster with 440Hz/1kHz tone, then an abrupt switch–off leaving just the "snow" and hiss from a no–signal condition.

Can anyone remember if any unusual patterns were transmitted during the night hours?

There used to be a site called "Test Card Memory Lane" that documented a lot of this but I think it's gone now!

Chris Williams
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Old 14th Jan 2019, 7:32 am   #2
bobsterkent
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Default Re: TV Transmitter Close Down/Start Up Routines?

have a look at the Transdiffusion site it has all sorts of start up routines etc there.

https://www.transdiffusion.org/
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Old 14th Jan 2019, 8:26 am   #3
rambo1152
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Default Re: TV Transmitter Close Down/Start Up Routines?

The thing I remember about that sequence of colour stills, is the limited brightness steps as they faded in/out perhaps 16?

Also, they may have each faded to black rather than cross-faded but I'm not sure.

There was a perception, at least in my head; that it was experimental, new-fangled digital computers etc.
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Last edited by rambo1152; 14th Jan 2019 at 8:33 am.
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Old 14th Jan 2019, 12:48 pm   #4
Julesomega
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Default Re: TV Transmitter Close Down/Start Up Routines?

Quote:
Originally Posted by Chris55000 View Post
Can anyone remember if any unusual patterns were transmitted during the night hours?
The tx were then turned off, manually by the staffed main stations, followed after a delay by the relay stations, so nothing was broadcast through the night, except when there were periodic test transmissions where the staff measured the transmitter performance using step waveforms, pulse and bar etc. I forget the test period, maybe 6 months?
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Old 14th Jan 2019, 1:00 pm   #5
'LIVEWIRE?'
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Default Re: TV Transmitter Close Down/Start Up Routines?

For quite a few years now, as we all know, all transmitters are on the air 24/7/365, so how do they monitor transmitter performance as there is no 'dead time' in which to send test signals, and, of course no Test Cards. Obviously TV service engineers can use pattern generators, etc. when setting up/repairing receivers and other video equipment, but what happens at the broadcasters end?
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Old 14th Jan 2019, 4:28 pm   #6
Nymrod121
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Default Re: TV Transmitter Close Down/Start Up Routines?

That sounds like one for Martin (at Emley Moor ... [both pulse and] bar 't 'at
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