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Why did DTT start with 2K mode?


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Old 06-05-2012, 09:20
Mark C
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There were virtually no changes after the switchover programme was announced, other than DSO itself, except a few retunes in order to allow another transmitter to switch. The only one I can think of was at Sheffield where Mux 1 moved from C39 to C63 to make way for pre-DSO HD services at Emley Moor.
Rowridge had a major reshuffle (all 6 muxes moved) in March 2009, to enable DSO at Stockland.

The original plan was for the BBC Mux to take E37, thankfully at the last moment Arq A took that allocation, and the Beeb took E34.
Nevertheless there were problems for many, owing to a lot of older Group A aerials rolling off at E34.
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Old 07-05-2012, 15:29
spiney2
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uk dsb was handed to murdoch on a plate by allowing him to break eu broadcasting laws.

in uk dtt was seen as a political fix to this and got rushed through by iba (itv).

the so called engineers who predicted initial sytem performance were complete idiots and practical system capacity was only half that expected. so OnDigital reached only 20% of possible audience instead of 80%. which slightly mucked up the finances.......

...... cofdm requires real time inverse fft and the chipsets able to cope with 8k were not around during uk launch. effectivly the uk system was proof of concept. after our disaster all other countries knew to quadruple the transmitter power and could plan accordingly ......
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Old 07-05-2012, 23:25
Winston_1
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uk dsb was handed to murdoch on a plate by allowing him to break eu broadcasting laws.

in uk dtt was seen as a political fix to this and got rushed through by iba (itv).

the so called engineers who predicted initial sytem performance were complete idiots and practical system capacity was only half that expected. so OnDigital reached only 20% of possible audience instead of 80%. which slightly mucked up the finances.......

...... cofdm requires real time inverse fft and the chipsets able to cope with 8k were not around during uk launch. effectivly the uk system was proof of concept. after our disaster all other countries knew to quadruple the transmitter power and could plan accordingly ......
Although what you are saying is basically true, as a patriotic Englishman I thing you could have put it more diplomatically. After all we did invent the system, we just rushed into it before others improved it.
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Old 13-05-2012, 00:18
pinkteddyx64
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France made a similar error by launching HDTV on the TNT in DVB-T in 2008 instead of waiting one year more and launching it directly in DVB-T2.
Due to the fact that there are now many millions of HDTVs only able to receive DVB-T, it's very difficult to launch new channels in DVB-T2.
Australia made an even bigger error by launching HDTV in DVB-T MPEG-2 in 2002 instead of at least waiting for something better than MPEG-2 to arrive. Yes, broadcast MPEG-4 didn't exist in 2002, but I thought that a country like Australia had a lot more sense than to rush into introducing something so big so early on!
Due to the fact that there are now many millions of HDTVs and set-top boxes only being able to receive DVB-T MPEG-2, and it's very difficult to launch new channels in even DVB-T MPEG-4!
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Old 13-05-2012, 00:35
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Australia made an even bigger error by launching HDTV in DVB-T MPEG-2 in 2002 instead of at least waiting for something better than MPEG-2 to arrive. Yes, broadcast MPEG-4 didn't exist in 2002, but I thought that a country like Australia had a lot more sense than to rush into introducing something so big so early on!
Due to the fact that there are now many millions of HDTVs and set-top boxes only being able to receive DVB-T MPEG-2, and it's very difficult to launch new channels in even DVB-T MPEG-4!
I just wanted to say welcome back, pinkteddyx64, and may you be with us for a long time.
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Old 13-05-2012, 00:50
pinkteddyx64
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I just wanted to say welcome back, pinkteddyx64, and may you be with us for a long time.
Awwww, thanks!

Back on-topic, why do some countries love rushing into doing things such as introducing HDTV using inefficent compression methods etc whilst we hold off for nearly a decade and then launch something using the latest technology?
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Old 13-05-2012, 01:06
Winston_1
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Back on-topic, why do some countries love rushing into doing things such as introducing HDTV using inefficent compression methods etc whilst we hold off for nearly a decade and then launch something using the latest technology?
Well you have to jump sometime, otherwise you will never launch.
Australia is one of those countries that does its own thing rather than adhere to accepted standards. It's the only country to use 7MHz channels on the UHF band.
Actually I think PnG might as well but they were an Australian colony at the time anyway.
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Old 13-05-2012, 01:16
pinkteddyx64
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Well you have to jump sometime, otherwise you will never launch.
Australia is one of those countries that does its own thing rather than adhere to accepted standards. It's the only country to use 7MHz channels on the UHF band.
Actually I think PnG might as well but they were an Australian colony at the time anyway.
I don't think that PnG even has any digital terrestrial television services.
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Old 13-05-2012, 18:54
technologist
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Australia made an even bigger error by launching HDTV in DVB-T MPEG-2 in 2002 instead of at least waiting for something better than MPEG-2 to arrive.:

But like the USA, Australia was looking for something which was (a large chunk of) one programme per UHF channel -
and so MPEG2 HD was the obvious bit filler that they were looking for.
they did not want additional channels and tried to limit even daughter channels .
They simulcasted HD and SD in digital and SD in analogue ......
So very different from the multichannel UK ...
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Old 13-05-2012, 18:58
pinkteddyx64
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But like the USA, Australia was looking for something which was (a large chunk of) one programme per UHF channel -

and so MPEG2 HD was the obvious bit filler that they were looking for.
they did not want additional channels and tried to limit even daughter channels . They simulcasted HD and SD in digital and SD in analogue ......
So very different from the multichannel UK ...
Similar to how we regret being an early adopter of DAB and being envious of some other countries using DAB+, we would have been moaning about how we regret being early adopters of HDTV technology if we had used MPEG2 HD back in 1998!
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Old 13-05-2012, 23:50
Winston_1
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I don't think that PnG even has any digital terrestrial television services.
You are no doubt right. That does not alter the fact that I believe the UHF band uses 7MHz wide channels like Australia.
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Old 15-05-2012, 13:33
spiney2
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Although what you are saying is basically true, as a patriotic Englishman I thing you could have put it more diplomatically. After all we did invent the system, we just rushed into it before others improved it.
i dont think we did. we didnt invent cofdm and France was initially prime mover in Spectre.

the big mistake was performance prediction. done by complete gits hence rubbish. almost finished off itv completely.
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Old 15-05-2012, 13:43
spiney2
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Awwww, thanks!

Back on-topic, why do some countries love rushing into doing things such as introducing HDTV using inefficent compression methods etc whilst we hold off for nearly a decade and then launch something using the latest technology?
the usa had their computer semiconductor industry almost destroyed by japanese imports (due to much better manufacturing) and were getting paranoid about consumer elctronics. especially hi vision and muse which looked set to become world tv standards.

the policy of 8vsb - basically same as proven phone modem sytem so known to work, along with hd picture -was a deliberate ploy to stop an asian takeover. the atsc was federal and congressional.

the european route was via mac. inuitially to replace expired pal patents. then an upgrade path to hd ....
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Old 16-05-2012, 15:09
marceljack
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Australia is one of those countries that does its own thing rather than adhere to accepted standards. It's the only country to use 7MHz channels on the UHF band.
You are right but basically it was rather logical to use the same channel width in UHF and VHF with the B/G system in the sixties.
8 MHz channels were a waste of spectrum (12,5%) with this standard (until stereo transmissions started when this "waste" has been reduced by 400 kHz or so).
Anyway the channel width is not a big issue for a DTT receiver as all DVB-T and T2 demodulators can be switched between 6 / 7 / 8 MHz by software.
Its a completely different story beween DVB-T and T2 or MPEG-2 and MPEG-4 !
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Old 16-05-2012, 22:23
Winston_1
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You are right but basically it was rather logical to use the same channel width in UHF and VHF with the B/G system in the sixties.
8 MHz channels were a waste of spectrum (12,5%) with this standard (until stereo transmissions started when this "waste" has been reduced by 400 kHz or so).
Anyway the channel width is not a big issue for a DTT receiver as all DVB-T and T2 demodulators can be switched between 6 / 7 / 8 MHz by software.
Its a completely different story beween DVB-T and T2 or MPEG-2 and MPEG-4 !
Don't agree. The rest of the PAL western world (except Ireland and SA which used 8MHz at VHF) used 7MHz bandwidth at VHF and 8MHz at UHF. Australia should have used the same standard as did NZ around the same time.

In theory all DVB-T/T2 demodulators can be bandwidth switched, in practice no UK boxes can be switched except the no longer available Woolworths Worthit box.
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Old 18-05-2012, 01:32
kruador
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the big mistake was performance prediction. done by complete gits hence rubbish. almost finished off itv completely.
When will you stop repeating this nonsense? The BBC, and the BBC's and IBA's former transmission departments (by this time, Crown Castle and NTL) did the predictions, performed measurements to get correlation between prediction and actual to improve the predictions, and they published white papers on how they did it. See UK DVB-T Network Planning and Coverage Verification, UK Planning Model for Digital Terrestrial Television Coverage, and Multiplex Coverage Equalisation. The fault was in not realizing that people wanted the entire channel line-up and were not happy if they could only get the PSB muxes. To be fair, most users had bought onDigital's equipment and were subscribing to its services, on the three weakest multiplexes, they hadn't bought free-to-air equipment (rare at the time) for the digital versions of BBC One, Two, ITV1 and C4.

The predicted coverage levels were predicted for aerial systems in good condition; there was a serious underestimate of the general condition of aerials, which was picked up for switchover. See for example Domestic TV Aerial Performance, a research report for Ofcom.

ITV was not and could not have been affected. onDigital was set up as a limited-liability company in its own right. "Limited" means that the liability to any creditors is limited to the share capital of that company itself - there's no comeback on the owners of the company, even if those owners are other companies. The Football League's bid to 'look through' the limited liability structure failed, they got barely any of the money that was owed, and some clubs suffered heavily because of it.
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Old 18-05-2012, 02:33
Ray Cathode
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ITV was so worried that its name was about to be permanently associated with a liquidated company, that on the day before it failed the name was changed from ITV Digital back to On Digital. The latter remains listed at Companies House in the liquidated section.

If that's not proof of potentially serious effects on ITV, I'll eat my hat.
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Old 18-05-2012, 11:28
spiney2
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When will you stop repeating this nonsense? The BBC, and the BBC's and IBA's former transmission departments (by this time, Crown Castle and NTL) did the predictions, performed measurements to get correlation between prediction and actual to improve the predictions, and they published white papers on how they did it. See UK DVB-T Network Planning and Coverage Verification, UK Planning Model for Digital Terrestrial Television Coverage, and Multiplex Coverage Equalisation. The fault was in not realizing that people wanted the entire channel line-up and were not happy if they could only get the PSB muxes. To be fair, most users had bought onDigital's equipment and were subscribing to its services, on the three weakest multiplexes, they hadn't bought free-to-air equipment (rare at the time) for the digital versions of BBC One, Two, ITV1 and C4.

The predicted coverage levels were predicted for aerial systems in good condition; there was a serious underestimate of the general condition of aerials, which was picked up for switchover. See for example Domestic TV Aerial Performance, a research report for Ofcom.

ITV was not and could not have been affected. onDigital was set up as a limited-liability company in its own right. "Limited" means that the liability to any creditors is limited to the share capital of that company itself - there's no comeback on the owners of the company, even if those owners are other companies. The Football League's bid to 'look through' the limited liability structure failed, they got barely any of the money that was owed, and some clubs suffered heavily because of it.
no. the man in charge of of OnDigital said "the engineers" predicted 80% coverage. But the actual level was 20%. Hence the financial disaster.

Partly inadequate aerials. assuming everyone was getting analogue at 50 dB sign to noise was just stupid, But also the simulations for difgital reception were wrong. the main model used was simple rayleigh scattering. whereas the actual situation is far more complicated with something like an inverse forth power law in urban areas ......
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Old 18-05-2012, 11:56
Mark C
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no. the man in charge of of OnDigital said "the engineers" predicted 80% coverage. But the actual level was 20%. Hence the financial disaster.
.

It was bad, but never as bad as 20% coverage.

Please provide documentary evidence of your assertion ?
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Old 18-05-2012, 14:46
spiney2
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i am quoting directly from what the chief exec of itv digital said when he resigned.

should still be on web somewhere.

around time freeview started there was a partial apology with several technical papers explaining the various mistaken assumptions leading to crap predictions.

the difficulty with broadcast cofdm is the full "almost shannon" theoretical capacity canot be used since reception has huge range of s/n values.

the system verification done by bbc transmitters is still online at ebu. driving around in a van measuring field strengths in open countryside. not a good test ......
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Old 18-05-2012, 15:31
Mark C
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i am quoting directly from what the chief exec of itv digital said when he resigned.

should still be on web somewhere.
Good, then find it, and quote it please, (you've made the assertion, it's YOUR job to qualify it)
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Old 18-05-2012, 15:36
pinkteddyx64
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the difficulty with broadcast cofdm is the full "almost shannon" theoretical capacity canot be used since reception has huge range of s/n values.
Is DVB-T2 at the "shannon limit"? In other words, will there ever be a DVB-T3?
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Old 18-05-2012, 15:54
DX30
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Not at, but it is close, see
http://broadcastengineering.com/imag..._fig2-w700.jpg
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Old 18-05-2012, 16:03
joshua_welby
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Is DVB-T2 at the "shannon limit"? In other words, will there ever be a DVB-T3?
Good Question

I was thinking about this the other day
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Old 18-05-2012, 16:04
pinkteddyx64
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So does that mean that a DVB-T2 multiplex could be, in theory, be stretched to a maximum capacity of 45Mbps?
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