Date   : Thu, 26 Nov 2009 22:21:48 +0000
From   : darren.storer@... (Storer, Darren)
Subject: Teletext receiver revisited

Hi Rob,

I don't suppose that you remember the occasion when you sent me a series of
frame grabs from BBC1 via a modem and in the opposite direction, I sent you
the corresponding teletext subtitles (from a Morley teletext adapter)? Using
this crude method, we watched Wonder Woman (at different locations) on green
screen monitors. It couldn't have been later than 1984.

In answer to some of the earlier technical queries, from memory you will
find teletext data on UK terrestrial TV from around line 7 upwards but line
19 is reserved for the Insertion Test Signals (ITS). As it happens, I took a
snapshot of line 19 from my amateur TV station, a couple of weeks back:

http://www.g7lwt.com/documents/datv/70cm/VITS_PLOT.jpg

...in the left hand 10% of the plot, you can just see the end of the
teletext data on line 18 of my transmission.

After the ITS on line 19 there uses to be "in house" studio data up to line
22, then the actual video field started. This is all from memory, so I might
be slightly out.

Cheers

Darren


2009/11/26 Rob <robert@...>

> On 26/11/2009, Tim Matthews <tim.matthews@...> wrote:
> >> I remember having fun, once, years back in the days of
> >> analogue satellite TV finding hidden data on MTV pages 1AA
> >> 1AB etc .. (had a tv that allowed you to go "up" and "down"
> >> page numbers that included the alphabetic pages!)
> >
> > Can you remember what was on them...?
>
> I seem to recall there was some Reuters stuff on there, but we're
> talking about 15 years ago here, so I can't actually remember!  I
> think some or most of it was further encoded.
>
> Rob
>
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