External Teletext Decoder. Is there such a thing?

[Ted Kendall]

Originally Posted by 2ombieboy

Hi guys looking to capture pages from teletext from laserdisc and vhs/Betamax tapes. but modern pcs just carnt do it. was there ever a box that would sit on a none teletext tv and push a teletext signal to it so an old set could be used. rf in and out. and you could control it with a remote or key pad/button press. or was there an old say windows 98/xp computer capture card that would capture teletext not just display it.


not sure if such things exsist just want to archive myt tapes and laserdiscs


Alan

Labgear made a set top box much as you desribe. We had one - long gone, I fear.

[ThePillenwerfer]

There are a couple of such devices toward the bottom of this page: https://www.radios-tv.co.uk/radios-t...on/#more-36170

[TonyDuell]

As others have said, external 'set top box' teletext decoders certainly existed. I have a couple.

A neighbour where I used to live built the Wireless World one when it was published and gave it to me many years later. It uses the old Philips chipset (SAA5020/5030/5040/5050). I think it has ultrasonic (not IR) remote control.

I found the Radofin one at a radio rally some years back. I've never got round to tinkering with it, but I think again it uses the Philips chips

Although I don't (yet) have them, there were of course teletext decoders for the BBC microcomputer. The Acorn one used some of the Philips chips and connected to the computer 1MHz bus. There were third-party one using the later Philps chips (SAA5243, etc) with an I2C interface (bit-banged over a couple of lines of the user port).

Using a teletext PCB from some TV model connected to a computer that bit-banged an I2C bus was not uncommon at one point. I did it and probably still have the unit I made somewhere.

[andrewferguson]

There is of course the fantastic vhs-teletext software, which can try and recover as much of the original teletext pages from VHS tapes using a WinTV capture card and some clever software on a modern computer.

It takes a bit of time to process the signal, but the resulting files can be played back in an emulator that acts just like the original teletext.

(Note: I'm not in any way involved with the software, except that I have used it in the past and was mightily impressed by it).

[G6Tanuki]

There were certainly external Teletext-decoders available - I remember travel-agents having them! Forget the manufacturer, but they were a slim aluminium box that was designed to have the telly sat on top: suppose in modern parlance it would be a "Set-bottom box". Some also had a built in dial-up modem and keyboard-socket for connecting to central booking/reservation systems.

[Philips210]

Thanks for the link andrewferguson. It looks very interesting. I have quite a few old VHS cassettes from the 1990s and possibly a few from the late 1980s with many TV programmes recorded off air, so it would be great to see if there's any recoverable teletext info.

Regards
Symon.

[Philips210]

Originally Posted by G6Tanuki

There were certainly external Teletext-decoders available

Hi.

Yes, I actually picked up one for £1 from the local car boot sale a few months ago.
It is made by Ayr and has a built in front end (tuner and IF). I think the decoder itself has the Mullard/Philips chipset. I haven't actually opened it as yet but will try to find it this week and post a few pics.

Regards,
Symon.

[2ombieboy]

thanks I would be interested to see one

[Graham G3ZVT]

Originally Posted by G6Tanuki

There were certainly external Teletext-decoders available - I remember travel-agents having them! Forget the manufacturer, but they were a slim aluminium box that was designed to have the telly sat on top: suppose in modern parlance it would be a "Set-bottom box". Some also had a built in dial-up modem and keyboard-socket for connecting to central booking/reservation systems.

From your description these would likely to have been Viewdata terminals accessing the Post Office Prestel service, or some other privately run Viewdata service.

Teletext and Viewdata looked similar, using the same display spec. Often using the SAA5050 graphics chip.

[G6Tanuki]

No the ones I recall definitely had Teletext decoders and an antenna connection as well as the dialup thing. You could watch ordinary TV on the things! I don't think the dialup was for Prestel, from memory it went to the travel-agent's mainframe, from which you could then _also_ connect to a few airlines' reservation-systems.

(I remember being impressed by this when it was used to book flights to the US for my father in the late-1970s. Two different airlines used in each direction, with a layover in New York included - all booked as one transaction. What diabolical sorcery was this?)

[Dave Moll]

Originally Posted by rambo1152

Teletext and Viewdata looked similar, using the same display spec. Often using the SAA5050 graphics chip.

As did Mode 7 graphics on the BBC Micro, which was exploited by the Teletext adaptor designed for it.

[Scimitar]

Travel agents used Prestel but had access to a closed group for their use.

[SiriusHardware]

I made the accidental discovery many years ago that my Panasonic NV-F70 VCR could at least partly replay teletext data from recordings - not seamlessly / reliably like the original off air recordings, but what I was mainly interested in was using it to recover / identify the time / date at/on which the original recording had been made. That normally worked quite well. It's interesting to try to browse through the teletext news pages of the day as well.

Afterthought: Does this work with DVD recordings made from analogue off-air transmissions? I have never tried that. I think by the time I had an HDD/DVD recorder it already had a DVB tuner, so all my DVD recordings are from DVB.

[2ombieboy]

any one have information on this its a decoder that's on ebay but not sure its what I am looking for https://www.ebay.co.uk/itm/Colby-Vid...gAAOSwbiFZOu8d

[cmjones01]

If you're wanting to decode teletext data from VHS recordings, that's fiendishly difficult and has only become feasible recently thanks to modern digital signal processing techniques working on captured video data. Any external decoder from 'back in the day', such as those mentioned here, has next to no chance of working on VHS, a small chance of working on S-VHS, and would probably work quite well on laserdisc.

Chris

[2ombieboy]

I want to get pages off laserdisc, its a fine clear signal works fine on my tv so a old external decoder should have no problem

[Maarten]

Originally Posted by G6Tanuki

There were certainly external Teletext-decoders available - I remember travel-agents having them! Forget the manufacturer, but they were a slim aluminium box that was designed to have the telly sat on top: suppose in modern parlance it would be a "Set-bottom box". Some also had a built in dial-up modem and keyboard-socket for connecting to central booking/reservation systems.

While based on Teletext, that system was called Viewdata. Some early Philips Teletext decoders actually had the connectors on them to extend to a full spec Viewdata system, and I think one of the early continental teletext sets indeed came with a combo decoder.

Travel agencies over here, used standard CTX colour sets with a Viewdata system built in by a third party.

[tony brady]

I had the complete teletext/ view data set of boards that were fitted to the Thorn 9600 chassis I think, the memory is hazy now but I should still have the manual somewhere.

It consisted of the Philips made ( I assume, it wasn't Thorns) teletext board which was about 15cm square glass fibe and double sided.with the 1st gen of chips and several connectors. It interfaced to the viewdata board which was sandwiched on one side of the teletext board and another board was the phone line interface.

As I was only interested in the text board I binned the other parts but did make 2 decoders for my friend and I. As we were Thorn group we called Gosport and they sent us TX10 remote handsets and the receiver part and trim from the set. I still have mine in the loft.

[Studio263]

Many of B&O's TV sets of the Teletext era made the output of the Teletext decoder available at the SCART socket, the idea being that it was then possible to record TV programmes complete with Teletext subtitles. That's one idea, but the results may well be in monochrome.

More usefully, the Thomson / Ferguson ICC5 chassis encoded the output of its Teletext decoder as PAL, it wasn't presented as RGB to the screen. As well as this making the text display washed out, fuzzy and subject to the whims of the user colour control, it means that the fully decoded teletext page images are present in the receiver as CVBS and in colour. It may even be present at the SCART socket like this, who knows?

Finding an ICC5 that still works, there's the challenge...

[TonyDuell]

Originally Posted by Studio263

More usefully, the Thomson / Ferguson ICC5 chassis encoded the output of its Teletext decoder as PAL, it wasn't presented as RGB to the screen. As well as this making the text display washed out, fuzzy and subject to the whims of the user colour control, it means that the fully decoded teletext page images are present in the receiver as CVBS and in colour. It may even be present at the SCART socket like this, who knows?

Finding an ICC5 that still works, there's the challenge...

Are you sure about that? The teletext PCB uses an SAA5243 chip which outputs RGB. It's fed to the video switching/matrix IC in the colour decoder which as far as I can determine keeps it as RGB. I can't see any way for the teletext video to be come PAL in this chassis.

I have a NordMende-badged ICC5 TV here with various faults. I am thinking of stripping it for useful parts fairly soon (like the teletext ICs) but if there is any interest at all in it I would offer it complete here.