Total loss of Irish teletext services with a hotel TV system after changes for 'ASO'

Antenna

I was at a meeting at the Carlton Hotel, Kinsale Co. Cork recently and also got to see what was available on the TV in one of the rooms there.
(The Philips TV was a few years - obviously not saorview capable)

THe 4 Irish channels were now obviously being sourced from Saorview (no 'X 24 October' visible and RTE2 had the HD D.O.G.) and modulated as analogue channels on the hotel system (for non- Saorview TVs which would be the majority of TVs there) - as the case with the main UK channels (via satellite).
Went to RTE1 and pressed the teletext button to look up news headlines/results on Aertel to find NOTHING. There was zero text on TG4 or TV3 either.

I am aware that there is no traditional teletext data on RTE2 via Saorview, but it should still be there with RTE1, as well as TV3 and TG4.

The TV's teletext decoder was obviously functioning OK, as Channel 4's traditional teletext service came up OK, and P888 subtitles worked on BBC channels.

Aertel is still a very useful service for many people so unfortunate it was not there.

Any Saorview box I have seen inserts the traditional teletext data in the VBI to anything connected by its SCART output (including modulators)
I think European boxes also generally handle 'traditional/WST teletext OK as well.

Is the above because the installer used UK Freeview-HD (which is MPEG4) STBs to receive the Irish channels for the modulators or what? UK Freeview does not use WST teletext so the boxes are likely not designed to facilitate it.


(incidentally the hotel system appears to be using Triax gear for satellite, as RTE Radio 1 and Newstalk were also distributed on analogue TV channels as received on Triax satellite receivers in radio mode.)

byte

I am not sure as I've never tried, but since Saorview STB's don't have modulators, I'd hazard an external modulator was used... does EBU text work over external modulators? It could be a case that the external modulators are ignoring the extra lines used for text?

zg3409

Yes I agree. An external modulator will remove text from the signal. Teletext is a signal added on to the sync pulse. Proper modulators generate their own sync hence remove teletext.

The ideal way is to have a Saorview decoder built into the TV but naturally this is not done in many cases. Normally proper analogue cable systems also include teletext.

watty

No, teletext works on any modulator.
But most boxes won't re-insert it in the video. You can test a box with SCART

Does TEXT on TV3 & TG4 only work using the Set-box remote (full screen) or work via TV Remote (re-inserted into video)?

The Interactive MHEG5 text only works on Set-box remote and replaces the normal video. Some setboxes may do Teletext this way.

You'll find on a Sky box where there is Teletext, the Sky mode Text won't show it, you need to be in TV mode and the TV is doing the work.

Teletext on DVB is transmitted SEPARATE to the picture and the setbox (DTT or Satellite) optionally inserts it into blank lines on the analogue video simulating off air TV signal.

Teletext has always worked with ANY modulator if a setbox is re-inserting it. It uses blank lines in Analogue signal that don't exist in a Digital picture. Nothing to do with syncs.

Nor does any domestic or Hotel system care about or generate sync pulses. If the Teletext isn't on a hotel system it's because the digital receivers are not inserting it.

Indeed fancier hotel systems have their own channel with their own teletext pages.

Modulators don't care what is in the lines nor how many lines there are.

byte

Thanks for clarifying - as I said, I wasn't sure, just threw the notion out there!

Cesium Clock

If the UK channels were being supplied via satellite ,analouge teletext would not be available,
And as far as I know analouge teletext is not part of the saorview spec

Rotating Egg

zg3409 wrote: »

Yes I agree. An external modulator will remove text from the signal. Teletext is a signal added on to the sync pulse. Proper modulators generate their own sync hence remove teletext.

It's already been posted; but that's rubbish, the modulator only places the composite video signal & whatever else is included in it on a RF carrier.

Cesium Clock

Rotating Egg wrote: »

It's already been posted; but that's rubbish, the modulator only places the composite video signal & whatever else is included in it on a RF carrier.

Most modulators only output mono audio, nicam signal is lost via inexpensive modulators

winston_1

Cesium Clock wrote: »

If the UK channels were being supplied via satellite ,analouge teletext would not be available,
And as far as I know analouge teletext is not part of the saorview spec

No such thing as analogue teletext. All teletext is and always has been digital. The correct term is world service teletext, WST, sometimes referred to as traditional teletext.

WST is broadcast on some Saorview channels and the spec says approved boxes should decode it and insert it into the field blanking. It is not in the Freeview HD spec however, even though the Icecrypt T2200 will handle it, though I don't think other Freeview HD boxes will.

Cesium Clock

winston_1 wrote: »

No such thing as analogue teletext. All teletext is and always has been digital. The correct term is world service teletext, WST, sometimes referred to as traditional teletext.

WST is broadcast on some Saorview channels and the spec says approved boxes should decode it and insert it into the field blanking. It is not in the Freeview HD spec however, even though the Icecrypt T2200 will handle it, though I don't think other Freeview HD boxes will.

So teletext and ceefax has always been broadcast digitally via an analogue service since its concept ?

The Cush

Cesium Clock wrote: »

So teletext and ceefax has always been broadcast digitally via an analogue service since its concept ?

Yes.

In the case of the Ceefax and ORACLE systems and their successors in the UK, the teletext signal is transmitted as part of the ordinary analogue TV signal but concealed from view in the Vertical Blanking Interval (VBI) television lines which do not carry picture information. The teletext signal is digitally coded as 45-byte packets, so resulting data rate is 7,175 bits per second per used lines (41 7-bit 'bytes' per line, on each of 25 frames per second).

http://en.wikipedia.org/wiki/Teletext

Antenna

Cesium Clock wrote: »

If the UK channels were being supplied via satellite ,analouge teletext would not be available,

The FTA Channel 4 on satellite DOES have what you call "analogue teletext" service (mainly horseracing pages). But AFAIK its not on the encrypted Channel 4 for Sky in Ireland.

The satellite BBCs do not have traditional teletext - as in Ceefax (i never said they do) but they do have P888 subtitles via traditional teletext.

winston_1

Cesium Clock wrote: »

So teletext and ceefax has always been broadcast digitally via an analogue service since its concept ?

That's right. The same applies to Nicam too.