Digital TV Technical Discussion

With WIN combining the 7 and 10 signals onto one transmitter in Mt Gambier and Loxton, the ACMA radcom database still has the full suite of transmitters for both areas listed. Which ones have been decommissioned?

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Seeing this row of Teletext racing results at a pub near where I’m staying made me think/wonder two things

  1. Does Seven still carry this as part of their DVB-T signal?

  2. Highlighted another advantage of DTV… I didn’t see a single character error at all… As in the old analogue days, incorrect/garbled characters would appear frequently.

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The Sky Racing transponder on the Optus 10 satellite carries the teletext for TAB agencies that have the full T-Mod installation.

Sky Racing transponder on Optus 10 1560E 2024-07-11

Some country WA venues without a T-Mod insert teletext on an RF channel using a Raspberry Pi setup, too. They use a modified script made to replicate BBC Ceefax in the UK.

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I saw this the other day at a pub. First time I’ve seen it in years.

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Seven’s Austext finished around 10 years ago Wikipedia says 2009, longer than I thought… In the end, the content was a shadow of what had previously been available on it.

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Does the separate WATAB teletext service still exist?
As STW9 was still carrying that service last time I looked in 2015?
And does the separately branded SKY WA services carry that teletext service instead of the Tabcorp TABTEXT service?

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I last checked in 2019 and WIN had just ceased teletext via 9Gem which prompted RWWA to develop the Raspberry Pi solution. I’d say STW would have stopped at the same time? Pretty sure WA TAB text would still exist as country meetings that aren’t carried on Sky still exist. Not sure if still delivered by IP or on the recently established RWWA feeds of Sky. Wish I could check.

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I am still curious about how Keno is distributed to venues.
Considering that in the Club Keno days it was on a dot matrix display I would imagine that each venue had a client and Keno pushes out the game results and the client would then play it out on the display?

Considering I’ve never seen a feed mentioned anywhere would it be a similar system and a computer at a venue generates the video feed?

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I remember that Ten had something like “Network Ten” on their analogue feed but I don’t remember if it was a specific page or every page except 801.

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Good question, I just assumed it was via the internet with mobile back up so it’s always on?

Could well be via satellite too, but I did notice when I was the club one time, I watched the results on my mobile phone vs the TV at the club, and the results were displaying on the phone a fraction ahead of the club’s TV.

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Yeah, I wonder how it’s distributed as well. I’ve seen it as a DVB channel at my local club because I’ve seen them change the channel to the club info/raffle screen, which is also on DVB. I imagine there’s an MATV setup and Keno is received via the internet and injected in, in addition to the info screen. I have also noticed a slight delay in venue compared to the Keno app, could this explain the slight delay?

I also once captured some internal graphics on the venue feed:

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Essentially it’s just a internet stream the same as any other video channel, was originally run by TABCORP NSW, then expanded around the country & is now part of the lotteries company that runs all the lotteries around Australia after the merger of TATTS & TABCORP a few years back.

From what I understand, it’s just a computer generated draw, which is streamed out on to the internet just the same as every other video web stream, & is then decoded on a computer at the pub/club etc. & distributed via their in house MATV system to various screens around the venue, the same as all the horse racing or other sports betting data.

It’s probably not running through the pub/clubs general office/public internet network, but through their secure gambling network that all the poker machines & gambling ticket terminals are connected to.

You can play & watch the Keno games on your phone app or computer.
Live draw is available direct to your phone/home right here https://www.keno.com.au/live-draw

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How was it done before that?

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Pretty much the same, but may have been carried as pure data along with other TABCORP racing information.

AFAIK it’s always been computer generated display, has never been a “live” video channel like a horse race or football game or Powerball draw, so would never have been carried on satellite as a separate TABCORP encrypted video channel, it would’ve just been data information, probably sent on an encrypted data information channel along with horse racing results, etc. as a TELETEXT sort of signal.

Back in the old days, TELETEXT was never anything particularly special, it was just information off a computer encoded as a digital data stream at a low bit rate on the Analogue TV signal hidden in the vertical blanking lines at the top & bottom of the screen, which to be honest isn’t much different from now. Dumbing it down to a not very technical explanation, Digital TV is just a digital data stream of video & audio at a high bitrate encoded as lots of sub-carriers on an Analogue signal.

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Think that was a placeholder wherein if no-pass through line 21 source teletext data was detected for an amount of time, there was a teletext inserter on the playout chain that would insert and send a clearing pulse on any hanging closed captions.

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But Ten never had teletext?

Or do you mean that Ten had a teletext inserter (but never used it) and had to put something in so that the captions would work?

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TEN and TVQ did have local teletext in the early 80s, as did TCN and ABN and others around the country, but short lived. Mostly on lines 19 & 20.

However, what I am talking about is closed captions or page 801 which is a single line (or magazine) of teletext data which is separately transmitted from other teletext systems like the former Austext. Closed caption teletext is inserted on line 21 in PAL analogue and SD digital. If I remember correctly, when you dialed up teletext page 801 on your remote when viewing TEN in Sydney, you would see a top of screen black box with 'NETWORK TEN" displayed which would clear off after a few seconds. You would not get this if the program or commercial on-air at the time had active closed captions, with the closed captions being displayed instead. This has since long gone, as in seeing “NETWORK TEN” being displayed.

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The PAL Teletext was inserted by a Tektronix VITS inserter that put the vertical interval test signals in. The VITS inserter had an auxiliary data input and that’s how the Teletext got to air. The actual content creation system 7 used was based on DEC PDP-11’s and Logica software.

TCN distributed its automation Stack(ie playout list) via the VITS inserters as well - other 9 stations could see what was happening in real time on the network distribution feeds from TCN with a stack decoder/display.

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All of Regional QLD will have Seven converted to MPEG4 from MPEG2 as I saw an ad on TV that talks about the changes and has this website for more info.

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