Freeview Lite?

I feel that this comment on the 'half a freeview' page is a little misleading. As I understand it, it is proposed to move 'five' to multiplex B at some time in the future, so everyboody will get it. Also, reading the proposals, I got the impression that three multiplexes is the MINIMUM that it is propose to provide - many relays may get more - a few will get all six. It's all down to population coverage, and the willingness of the commercial operators to provide the gear for stations having a relatively small number of viewers.

You are right, Five will move to one of the BBC muxes at switchover, as will S4C and S4C2 in Wales. This is to ensure that, as public service broadcasters, they have near-universal coverage in the digital world.


The move will be possible without displacing any BBC services, because at switchover the BBC will return from 16QAM to 64QAM mode but maintain equivalent coverage and robustness of signal thanks to the high power transmissions which will be possible post switchover.


The mode change will create capacity equivalent to two standard channels on each of the BBC's multiplexes - enough for five, S4C and S4C2.


the three commercial multiplexes will not have the same level of universal coverage after switchover as the three psb muxes you describe - though I'm not sure we can assume they won't roll out at all. It is the case that they are not obliged to reach the same level of coverage as the psb muxes - and indeed will not be able to achieve it for technical reasons. But they may make a commercial decision to extend their coverage substantially. (map)

I've added a page
Analogue shutdown simulation issues
that highlights all the issues with switchover on relay transmitters.

I read somewhere that 120 relays which are currently analogue only will get all six multiplexes, thereby taking the total number of transmitting stations with all six multiplexes to 200. The rest (800 odd) will only get 3 multiplexes, according to what I read. Why limit any relay which currently transmits four channels (BBC1, BBC2, ITV1 and Channel 4)? If four frequencies will be vacated at even the smallest relay, those could be re-used for MUXes 1, 2, A and B.

Nicholas, there is a simulation of the shutdown at http://www.ukfree.tv/simulation.php?i=0. There are no published lists yet of which extra 40 transmitters WILL get all six multiplexes. Details of what will happen to the frequencies cleared is at The Ofcom Digital Dividend Review (DDR):

• New mobile services, with high quality video and interactive media delivered to handheld devices.
  
• Wireless broadband services, with high-speed data and voice services.
  
• Wider coverage for advanced services in remote and rural areas. This spectrum is particularly suitable for low cost, wider-area coverage.
  
• Advanced business and broadcasting services, such as those used to support major sporting events.
  
• Additional television channels including possible High Definition (HD) channels carried on Freeview

The reason for the non-publication is that it is considered a "commercial decision" by the multiplex A, C and D owners to extend their coverage.

This all goes to show what a waste of time relay stations are. I don't know why people waste their time with them. Given the choice between a weak main station signal and a strong relay signal I would go for the main station every time. More choice, less co-channel interference. less risk if breakdowns and power supply failures.Sadly, too many aerial riggers take the easy option and just sling up a cheap comntract aerial on the local relay instead of putyting up a decent aerial on the main station.True, there are some remote areas where it is the relay or nothing but those are the esception

Jay

It is simply not acceptable to have less channels available in low population areas because of commercial considerations.

Ofcom should insist that all commercial operators provide a uniform service across the UK and where the population is below a certain threshold then grants should be available.

The arts council makes multimillion grants so that minority (though vocal) groups can enjoy entertainment such as local theatre, national ballet and opera.

I do not accept that satellite is a viable alternative as many households especially with children have more than one TV

Given the space saving of wall mounted LCD DVB TV's many households will not want an add on box cluttering the wall.

I think that the "1074" is a tad misleading as these 1074 transmitters do cover a minority of uk households. I don't know the exact (or approximate for that matter) breakdown of main verses repeaters consumers but I feel that this would be a better metric to use. Other than that, fantastic website!

The current 82 Freeview transmitters give full coverage to 73% of the population for all six multiplexes and 80% for "at least some channels". These percentages are from Ofcom: Driving Digital Switchover

Dear Sir There should be sky sports
on freeveiw it would be good.

Sky are considering a proper Freeview channel at the moment - this will replace Sky Sports News if it happens.

The information above about 200 DTT transmitters being equipped to broadcast the 3 commercial multiplexes (muxes) is seriously out of date.

The current position is that after DSO the 80 sites which currently transmit DTT/Freeview at low power are required to transmit the three commercial muxes COM1, COM2 & COM3 at high power.

Their coverage is expected to reach 90% of the population after higher than expected power levels were agreed by the ITU RRC in June 2006. The operators of the commercial multiplexes, ITV plc and NGW plc advised Ofcom confidentially in
September 2006 whether any additional sites over and above the current 80 will
be equipped to transmit the commercial muxes at DSO and we await the release of
this information officially.

In any event it is unlikely that the total number of transmitters broadcasting commercial muxes will exceed 100 and the additional
number above 80 is entirely up to ITV & NGW to decide. However whatever they
decide will affect the master frequency plan and infrastructure costs to the PSB
multiplex broadcasters, so that is why Ofcom has asked them to decide now.

There is no actual evidence what you say, sadly.

The evidence is contained within this consultation published after the end of RRC-06 in June 2006 by OFCOM in July 2006 here

http://www.ofcom.org.uk/consult/condocs/dtt_changes/dtt_changes.pdf

and by this response to the OFCOM consultation by the BBC here

http://www.ofcom.org.uk/consult/condocs/dtt_changes/responses/bbc.pdf

As I said in my earlier comment we await the outcome of this OFCOM consultation.

The reason why the commercial multiplexes COM1, COM2 & COM3 will be transmitted from a maximum of about 100 sites is because the recent ITU Regional Radio Conference which ended in June 2006 only approved frequencies for that number see

http://tx.mb21.co.uk/dso/facts.asp

also the ITU information is available here

http://www.itu.int/ITU-R/conferences/rrc/rrc-06/index.asp

Current information from the sources I have mentioned indicates that a maximum of 10% of the population will not be able to receive the 3 commercial multiplexes after DSO. If the 80 transmitter figure is increased then the percentage unable to receive all of Freeview will be even less than 10%.

There is plenty of evidence available but sadly as a self-professed expert you do not seem to know what is going on.

I'm simply not going to put anything on this site that is SPECULATION. Ofcom is responsible for issuing the licences to broadcast in the UK, and they cannot confirm yet - they will soon - if the commercial multiplex operators have applied for the licences to broadcast from more stations. Also, they cannot confirm that the multiplexes will change their designations, as these desigations are set by the 1996 Broadcasting Act.
If what you say is correct, Ofcom will confirm it soon.

As you could not have possibly read the documents that I referred to above in 8 minutes, I hope that when you do, you will retract your statement above "There is no actual evidence what you say, sadly". Speculation does not mean quoting known facts from publicly available documents from OFCOM etc. Your website will not be the last to get facts wrong.

In particular the master frequency plan will, according to the BBC, be continually changing almost until the last transmitter has been converted. Therefore everything on your site relating to projected frequencies is pure speculation according to your definition.

The PSB and COM designators are used within the industry to distinguish the current low power multiplexes (Mux1, 2, A etc) from the new high power multiplexes, as a new distribution system is being built and for some years both sets of multiplexes will exist and thus need to be differentiated as they will not be identical.

I've ALERADY read the documents you posted. There will be no mode change of multiplexes 2 and A, as these are already in 64QAM mode. I have no doubt that the frequency plan will change from time to time. However, there is no FORMAL announcement that the multiplexes will change their designations, whilst it is obvious that there is going to be a situation for some years that Multiplex 1, B, C and D are going to operate with 16QAM in some places and 64QAM in others, this does not PROVE that their designations will change. If you can provide some EVIDENCE for what you say, fine. But until there is OFFICAL annoucement of any changes I am not going to propogate speculation.

Although there will be no mode change of muxes2 and A, they will not necessarily be carrying the same channels after DSO. Some ITV regions are changing on mux2 and Tele-G and S4C2 on muxA are expected to move to a BBC mux.

But you are getting away from your original mistake in that your website is implying that anyone who gets service from a low powered relay will only get "half a freeview service" after DSO. This is wrong as after DSO the 80 transmitters will increase radiated power to increase coverage from the current 73% to about 90% according to OFCOM. Some of those on low power relays will then be able to get service from a high power site after DSO with all 6 muxes and all freeview channels. A responsible website would have reported this which is only what OFCOM have said they are currently intending to do. If they change their mind they will let us all know.

I stand by everything I have written above which is not speculation but a true representation of the facts from official sources listed. You do not seem to be able to take any criticism at all.

Please keep your comments polite. To address your points:

a) The ITV changes are going to happen way before switchover and this will effect the current Freeview multiplex 2 transmissions as well as analogue (and satellite) well before switchover.

b) The move of five, S4C, S4C2 are noted above. Tele-G broadcasts for one hour a day, so it's not going to be a massive problem.

c) Anyone who is currently using a relay transmitter WILL only get half-of-Freeview, ie three multiplexes.

d) The current coverage of 73% for the transmitters that carry all six multiplexes will remain until switchover, and will eventually rise to 90% by 2013 as the signal strength will be turned up. However this does not mean that anyone who is currently using a transmitter that does not have Freeview WILL be able to have all six multiplexes, it just means that people who use a main transmitter that is too distant for Freeview reception now will be able to receive all six multiplexes after switchover.

As you have now resorted to removing my perfectly polite posts pointing out your errors, I see no further point in continuing discussions. Your paragraphs c) and d) above contradict each other. SOME viewers currently getting reception from a low powered relay station WILL be able to receive all 6 multiplexes after DSO from one of the 80 high powered sites by getting a new aerial setup due to the higher than expected ERPs being agreed by RRC-06. Not all but some. In 2013

Only post that are rude are removed. There is no requirement to support Trolls on this website.
Your point is that some people using relay transmitters will be able to use main transmitters if they choose to turn around and/or replace their aerial, which is true. However, this does not negate the fact that they will not automatically get all the Freeview multiplexes.

Oh Dear!! I Have just happened upon the arguments above. In this hilly part of the country (Devon) I have found that ghosting of the main tx mux's causes an irregular pattern on the spectrum analyser (dips and peaks) causing poor BER. I know they used to say that a ghost signal would augment the main signal but this does not always seem to be bourne out in practice. When the main tx's increase the power of the digital transmissions, surely the ghost signal stength will also increase by the same amount. Will this cause a reduction of errors on the mux's? Only time will tell, but I have found that if there is a ghosting problem then it doesn't seem to matter if the incoming signal is strong or weak, the error rate seems to stay the same. Also during periods of high pressure, co-channel interference will wipe out some mux's altogether. Looking at the spectrum during these periods one can see the analogue signals poking through the top of the mux's. This problem even occurs at locations that normally give perfect digital reception. It will be interesting to see what the effect of co-channel interference will be when the interfering analogue channels are changed over to digital, especially after the power is turned up! Obviously at the moment we choose to use the local relay tx's for analogue use and hope to continue to use them after switch off. If we are to be given as few as 3 mux's (half a freeview service!!) then there is going to be a lot of dis-satisfaction when viewers start asking each other in the street if they saw so and so on the box last evening only to find that they were not in fact able to even see the item due to their location! (map)

John Hindley Aerial Services: From memory, the whole point about splitting the datastream into either 16 or 64 pathways, and then using massive guard intervals and combining this with a few other techniques is supposed to have two effect. The first is that the signal looks like "noise" when analysed with "analogue" equipment. The second is that two transmitters can use the same frequency much closer than analogue because most of the transmission is actually the "guard interval". There are two possible modes of operation: either synchronous (ie, in single frequency networks) where all the transmitters are fed from satellite signal and can be kept in perfect synch and the signal is supposed to be augmented. The second mode of operation (as used in the UK, multiple frequency networks) is that the signals from neighbouring transmitters (in effect, those over the "normal radio horizon") will be 'out of sync' (or possibly 100% different) so any interference appears during the guard interval.

I've thought about what you said about "irregular pattern on the spectrum analyser" and I suspect it might be a combination of analogue and digital signals coming in.
If this changes with the pressure then the signals are much more likely to be analogue which bounce around with the Inversion Effect.

This is WHY the analogue signals have to be removed from the network to provide full national coverage with DVB-T transmissions.

Yes, I should have made the situation clearer re analogue trasmissions superimposing on mux's during adverse weather conditions. I forgot to say that examining the spectrum of an affected mux using the Prolink4C Premiums' constellation feature allows one to examine each of the mux's 1000 odd individual carriers and the frequencies of the ones affected corresponded exactly to the interfering analogue vision and sound carriers. Indeed the frequency position of the sound carrier indicates that it is usually an English analogue transmission rather than one from the continent, indeed, very often one in the same line of sight of the wanted transmission, hence using a very directional aerial making absolutely no difference. Now,carrying on the discussion re ghosting of digital transmissions rather than interference from analogue sources. The problem seems to be caused by the ghost(s) being frequency selective, ie some of the mux carriers are received 'in phase' giving individual carrier peaks and some out of phase causing nulls - 'suckouts', in a way similar to the way of analogue signals losing their colour sub carrier, mono sound, banging, crackling and loss of nicam etc during ghosting. As an aside, what are your thoughts about SFN's. I find it works very well on DAB especially here living on top of a hill between 2 different transmitters where a simple dipole allows the two transmissions to augment one another. Ok for the national network but not so good for the commercials. Good for 'Gemini Radio (Torquay)' on the south facing side of the bungalow and good for 'Gemini Radio (Exeter)' on the northern side, each one carrying its own programme content. Down in the valley we have to use 5 element DAB arrays and align onto whichever transmitter actually works at all. Back to the subject under discussion. To me SFN's for freeview seemed to be the answer to a lot of problems, obviously too late now for it to be implemented however. National bounderies and the constraints of commercial mux's would also probably bring problems. As with all new technologies we will have to wait until the switchover really swings into action before the real outcome will become apparent - time will tell. Way back in the 1950's co-channel interference had never been experienced or indeed even taken into consideration. Theory assured us that no transmissions would EVER travel further than 'line of sight' at VHF and that impulse interference would be non existent at such frequencies. No one had ever heard of 'continental interference' or 'inversion layers'. Sunspot activity was thought to be non active at 50 Mc/s (Hz!!). All this interference only became apparent during the 1960's and I think, was one of the reasons for the coming of the UHF/FM sound carrier era, the powers that be and we aerial riggers thought (hoped) that this would be the answer to our prayers. How wrong we were!! Maybe Freeview will be successful, as I said,'time will tell'. I have always been a 'practical' chap and over the years have had cause to become a little sceptical about some of the thoretical answers. Maybe the real way forward would be to bite the bullet and abandon terrestrial TV and going fully over to satellite. You and I have already discussed elsewhere the governments plans to give over large chunks of the UHF spectrum to other terrestrial transmissions - mobile phones etc. That would also sort out the 'half a freeview' question. Anyway, good to air one views. Thank you once again for the facility and an excellent site. John. (map)

John:You are only looking at a very small part of the CODFM encoding strategy. For one thing, the constellation points don't refer to different carrier frequencies, as with analogue TV, but the carrier points of the system. The "constellation points" refer to particular decoded views of the signals which are brought together in different phases. The system use "fast Fourier transformations" to decode this information.


Because the system uses several different forms of encoding, such as the outer Reed-Solomon wrapper, convolution, trellis and error correction a certain level of interference from analogue transmitters can be tolerated, no matter if they "add" to the signal or cause "suckouts". The data is transmitted multiple times and the error recovery system can cope. Most of the time!


The different transmissions mediums (cable, satellite and terrestrial) tweak the DVB parameters to get the highest bitrates with the lowest possible BER.


I wouldn't expect from your location to get anything other the UK TV transmissions, even when Inversion happens.


I have spoken to Ofcom's frequency planning people about using SFNs (like they do in Spain, for example). Whilst they agree that they could be used in theory for the multiplexes that do not have local content, they point out that it could only work with a new network of transmitter sites and most people having to have a new aerial and point them at new transmitters, which they felt was "not possible".


It works OK with DAB, because the DAB service uses QSPK with over-the-top error correction and massive "guard intervals".


It is interesting that no-one thought that Inversion would happen in the 1950s, or co-channel interference. But the design of DVB-T takes these problems into account, and most of the techniques I listed above are attempts to deal with them.


Of course there are going to be unforeseen problems when switchover starts for real. The switch to 64QAM mode, for one thing, will stop most loft aerial working. Going down from four analogue transmissions to three digital at the 1000+ "repeaters" hasn't been done anywhere else in the world. Upgrading the world's original broadcast TV network was never going to be easy.


The BBC are soon to launch their "Freesat" service will provide (almost) 100% coverage of the UK with HDTV, but satellites are still prone to "single points of failure" and are owned by foreign governments, so I think it's in the nations interest to keep the terrestrial network.

Hi Brian. Thank you once again. My theoretical knowledge is certainly lacking on the digital front and I accept gratefully the info you have just supplied. This sort of info is valuable and certainly not generally available so at least it is now being brought out into the public domain. Reading your second paragraph above makes me realise that I may be confusing you about the peaks and suckouts. These seem to be being caused by frequency selective ghosting of the digital signal and not by interference due analogue transmissions, sorry about that. I only base my observations on practical experience by simply turning the receiving aerial into the ghost and noting the effect on the BER etc. Stupidly I had also forgotten that DAB was QSPK based! A lot of time and a lot of our money is and will continue to be spent by the government and ourselves due to the switchover so obviously success is paramount. I take your point about the BBC 'Freesat' service being dependant on satellite ownership by foreign governments but am I not right in thinking that a lot of our terrestrial network is and will continue to be satellite fed anyway? I suppose that over the last 50 years of my working life in the what may now almost be classed as the aerial installation 'profession' rather than trade, my views have gradually declined from optimism not to pessimism but to realism. (On a personal note this realism took on a whole new meaning 14 years ago when the need arose for me to have a heart transplant - or else, but that's another story! If you want to know more about this then please feel free to e-mail me direct.) Thank you once again for the time spent discussing the above. John. (map)

John: the problem of ‘ghosting’ or ‘signal reflection’ is dealt with in DVB-T (it’s not a problem for digital cable or satellite) by having the very large ‘guard intervals’ in the carriers. As these are designed to occur in out-of-sequence in each of the subcarriers, it is possible to both detect the reflected signal and, by sending the data though multiple carriers, correct for it.


I usually find that you can usually receive the 16QAM multiplexes from a Freeview transmitter even when there is considerable ghosting on the analogue picture.


I remember when I first saw DVB-T demonstrated at the IBC conference in Amsterdam and I had personally been quite sceptical about the digital service working in practice. It worked fine in the lab, but as you point out these things are so much more challenging in the real world. So I was pleasantly surprised to see digital TV being received in perfect quality from the inside of a tram!


In practice the BER has to be tiny, but as I am sure you have found in practice, either you have a good enough signal and everything is fine or the BER is so high the channel is unwatchable.


I am really concerned about the amount of money that is being spent on digital switchover! There is the £600m that the BBC has to pay to support certain elderly people which should really be spent on informing, educating and entertaining.


In actual fact the terrestrial (and indeed cable) networks are not fed from satellite. They are supplied by bi-directional high-speed fibre optic networks. Some of them are fed by back-up satellite signals in the case of failure. The analogue networks are fed as “motion JPEG” at around 8Mb/s.


The repeater networks are fed from the main transmitters on analogue, but all 80 Freeview networks are fed by fibre-optics too.


Remember that BBC One and ITV1 have a huge number of regions, BBC TWO has nations, C4 advertising regions, which makes digital multiplexes 1, 2 and A have regional versions. This also means many Freeview transmitters report the wrong transmitter name to a set-top box, because it is the ‘regions’ that are multiplexed.

Hello Brian. Well, we seem to be clearing up the problems quite well between us, thank you for the info re TX feeds. Yes, Beacon Hill reporting that it is Stockland Hill is a continual source of confusion and irritation to viewers. At least I can now tell them that the TX's are fibre optic linked rather than satellite linked or over the air relaying of the signals aka relay TX's. (problably continue to tell them this for ease of explanation but will have to play it by ear after observing customers understanding of the situation!) Re, explaining reception problems. To explain the 'digital cliff effect I usually say to customers that rather than a good - moderate - poor pictures as in analogue , I tell them that in digital we tend use the technical term "all or bugger all"! Thanks, John. (map)

John: Yeah, I think all the transmitters in Wales are "Wenvoe"! Digital TV also tends to be digital (0 or 1) in terms of reception too. I think I often end up saying the "reception of analogue signals from a transmitter is no guide whatsoever to the strenth of digital signals from that transmitter".

I agree. Probably best to wind up for now. Please feel free to e-mail me personally if you want to keep this contact going or we will end up boring the readers of this column, I assume you can extract my e-mail address. One last one! Does it make you laugh, wince or dispair at some of the spelling and other oddities that seem to be happening to the written word in e-mails, or is it me being piccy? :=} John. (map)

John: The policy is not to correct or be picky about people's English... this is a site for people interested in digital TV, not verb declination.

Sorry! John. (map)

John: erm.. I just meant that the whole digital TV thing is complicated enough to only insist things being right when they matter, such things as wideband and groups and multiplexes etc.

Brian
In your analouge shutdown simulation issues for March 2012 you do not mention the transmitter that I receive my signal from Winterbourne Strickland any reason (map)

Doug Cheney: Please see Winterbourne Steepleton digital switchover date | ukfree.tv - independent digital TV and switchover advice

Hi,
Can someone tell me were the funding comes from for all the digital transmitter conversion work?

Regards
Dave

I have been reading the above with interest, although some of it is a bit technical! Regarding the comment above that "The switch to 64QAM mode, for one thing, will stop most loft aerials working."

Did I not read somewhere that after switchover that transmitters will broadcast DVB-T using 8k subcarriers instead of the current 2k? If so, then presumably that will include the existing multiplexes which broadcast in 64QAM mode.

Surely that will have the effect of making the transmissions not only more robust but easier to receive? In fact I have been wondering whether, my existing aerial distribution system -which works perfectly, will be swamped after switchover!

Patrick
North Worcestershire (map)

BBC NEWS | Scotland | South of Scotland | Dispute over digital TV 'lottery'

Recent announcements about shifting current Mux B transmissions elsewhere to allow 4 hd channels on Mux B lead one to ask if the current freeview lite transmitters will get hd transmissions?

Rod Grey: The good news is that all UK transmitters will get the HD service, which will be three HD channels, a BBC HD, ITV1 HD and Channel4 HD. The bad news is that the quality and number of other services will drop.





Basically you will not have one ITV channel and one C4 channel and you will miss a second C4 channel in wales (but gain S4C). You will get five though.


Also See BBC Freeview services to drop 33% in quality in 09 | ukfree.tv - independent digital television and switchover advice, since 2002

There is no terrestrial digital service at the moment from our relay (Corris) post code SY20 9EX so I have an old Sky box set up with a free sat from sky card. Will this work with the freesat transmissions. If I need a new box which one should I get? there are currently ones without Hard disks in Lidl for £40 and with hard disks for £130 will these work with freesat? Will the old sky dish work? At switch over how many of the MUX's will be output on Corris?

Thanks for a very informative site,

Martin (map)

Martin Brett: For details of your transmitter ... digital switchover date | ukfree.tv - independent digital television and switchover advice, since 2002 you have a Sky box with a card, you can get Freesat from Sky.

Booxes from Lidl are not Freesat boxes, just free satellite ones. Freesat boxes have a full seven-day programme guide and also "MHEG5" text and interactive services, plus support for the correct channel numbers and national/regional services.

Thats well unfair, we just really can gt a signal from winter hill or nearby freeview mast Saddleworth, so we have to watch some lousy three multiplexes from the Delph transmitter in 2009. I was getting really excited when i found out i was going to get sky sports news and other sky picnic. I cant afford to get a new aerial for Winter Hill or Saddleworth. Or I cant afford Sky. And there is just no reason atall why we cant have all channels. On a Possitive note, the post code checker is well more reliable the digital UK one, and Digital UK didn't even make it clear the I would be recievin half the chnnels. Its really ****** me off.

If you happen to live in a relay transmitter area (like just about the whole of West Cumbria, including the towns) they've just decided to "upgrade" today and remove two more of the limited number of channels we actually do receive.

Oh, and to make us feel really good all the "experts" are doing the rounds going on about how uninportant all us relay transmitter people are

mcshroom: On the plus side, you now have ITV2+1 and FIVE, and you will be be able to watch BBC HD, ITV1 HD and C4 HD from sometime next year!

I'm annoyed that I paid money out on freeview+ boxes, expecting decent freeview channels after 10th March 2010, only to find the SY20 area gets the basic channels.

I could have saved my money and put it towards Sky TV.
Funny how different parts of the country are treated by Ofcom, when they're raking in big salaries to look after us all

Poor show all round, me thinks

T. Thomas: It's nothing to do with Ofcom, they provided the frequencies and the commercial operators declined to use them.

You should, as the Freeview+ box and presales material says, check your postcode before you buy.