All posts by Mike Dimmick
Below are all of Mike Dimmick's postings, with the most recent are at the bottom of the page.
The list of FM transmitters carrying BBC Radio nan Gaidheal is at BBC - Help receiving TV and radio - Transmitters and you can find FM coverage maps at mb21 - Transmitter Information - VHF Analogue Radio Transmitters - BBC National Radio - again, main transmitters only. Power for the Gaelic service is often lower than for the BBC National Radio services, so the coverage areas will be smaller for some transmitters.
Do also note that the population is more sparsely distributed in these areas, so absence of coverage of land area may not indicate that there is any population that is not covered!
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Nick: HD services start at switchover, apart from the few transmitters providing an early, temporary, HD service. These are large population centres where the HD signal could be crammed in, usually at lower power than the other multiplexes. The temporary service is replaced by the permanent service at switchover.
Early HD services are available from:
Lichfield, for Birmingham
Crystal Palace, for London
Black Hill, for Central Scotland
Pontop Pike, for Newcastle
Emley Moor, for Leeds
Winter Hill (for Manchester and the north-west) gained HD services at switchover, as have all transmitters which switched over from March 2010 onwards. Those that switched over before this were gradually upgraded between March and November last year.
No more early HD services are planned. HD services from Sudbury, and its relays, will start on 20 July, a little over a month away.
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Ian: Channels can choose to be 'free-to-view', though, only requiring the one-off purchase of a viewing card ('Freesat from Sky'). Dave is a subscription-only channel on satellite, you must subscribe to the appropriate Sky channel package and keep paying every month to keep the channel.
Sky distribute a (small) proportion of subscription revenue to the channels in the package, and the cost of carriage in the EPG is believed to be lower. Sky may also have offered to 'help' the channel with transponder space or rental costs.
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Speug: Brian went to a lot of effort to add those and is now being stubborn about removing them.
In short, they are wrong. They only ever appeared in an appendix to an Ofcom consultation about what to do with 'interleaved' spectrum, possible frequencies that could possibly made available, to cover a limited part of the transmitter's coverage area.
There has been no auction to licence these frequencies, and there is no date set for any auction. They might form part of the Culture Secretary's pet Local TV project, but that seems to be mired in disagreements over the scope. Even if local TV does get off the ground, it might not use the frequencies shown, as it may be better to use other frequencies for the job (for example, the Channel M multiplex in Manchester was actually allocated C56 where 'NEW7' was shown as C57).
To sum up, you're not missing anything now and you're not that likely to get anything in future.
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Ann Tait: Is there only one aerial on the building, or is there an aerial for each flat?
Your mother's situation may be like mine, that there is one aerial, the aerial cable comes in to one flat and is then split via an active splitter between the TV in that flat, and a cable running to the other flat. (I rent a converted terrace.) If that's the case, ask the upstairs neighbour to check that the powered splitter is still plugged in, and that it's working.
Some powered splitter equipment automatically reverts to bypassing on the first socket if the power supply fails or is unplugged. If this equipment does this, the neighbour may still have excellent reception.
You're only 5km away from the transmitter and it's fairly powerful for a relay, so signal strengths could still be high enough to use a passive, unpowered splitter instead. They could be high enough to get a distinguishable, though not perfect, picture without the aerial.
If there is one aerial per flat, or the splitter is passive or a powered splitter is definitely working, check that all cables are properly connected and that the cable is making proper contact with the connector. If there is a separate aerial, ensure it is pointing in roughly the same direction as the other and that it appears to be intact.
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steven wallace: At 20km from Winter Hill, with clear line of sight, too much signal is the most likely explanation. If there is a booster or amplifier, try removing it.
If that doesn't help, and this aerial was fitted by an installer, get them to come back and reduce signal levels, or otherwise do what's necessary to sort it out. If it was DIY, try adding an attenuator, and/or swap for a smaller aerial such as a log-periodic type, e.g. Online TV FM DAB Aerial sales .
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Green Gordon: OFcom have a map of licensed DAB areas at Ofcom - Digital Radio Coverage Map (DAB Primary Protected Areas) .
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Lisa: PSB, Public Service Broadcasting multiplexes. PSB1/BBC A carries all the BBC's SD channels, interactive services and radio stations. PSB3/BBC B/HD carries BBC One HD, BBC HD, ITV1 HD and Channel 4 HD.
PSB2/D3&4 carries ITV1, Channel 4, Channel 5, and whatever else the ITV companies and Channel 4 decide to carry on their respective halves of the remaining capacity. At present that's ITV2, C4+1, More 4, E4, and ITV1 +1.
Digital UK's predictor shows you have a good chance of reliable reception on all six multiplexes from both Sudbury and from Crystal Palace after their respective switchovers are fully complete. You aren't expected to get reliable service from Sudbury COM5 and COM6 (Arqiva A and B) until the final channel change in June 2012.
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Nick: Challenge is carried on Mux A/SDN. At switchover step 1, 6 July, this takes over the current main BBC multiplex's channel. It is due a power increase to double the current level, 14kW, but it's not clear whether this happens at step 1 or step 2 - Digital UK's predictor for Lisa's postcode shows the same (poor) prediction for 6 July as it does now, increasing to good at step 2 on 20 July.
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Jack: Since 2007 the transmitters have all been owned and operated by Arqiva. Before then, about half were owned by National Grid Wireless and half by Arqiva. The Arqiva half were originally set up by the Independent Broadcasting Authority and the NGW half by the BBC. Both were privatized, the IBA in 1990 and the BBC transmitter network in 1997.
Craigkelly was originally an IBA transmitter.
Permitted power levels and radiation patterns are regulated by Ofcom, but generally the broadcasters have been allowed to set whatever levels they feel are necessary. Most sites have had a reduction of 7 dB (one fifth) from their analogue signal levels, for the PSB muxes, with the COM muxes 3 dB (one half) lower than that. Some sites that previously had directional aerials to avoid interfering with other regions or other countries now have better directional properties on their new aerials, and are allowed relatively higher signal levels. For example, Rowridge only has a 4 dB (60%) cut, while Dover has a 1 dB cut (20%).
Craigkelly *does* transmit the full range of channels. If you can't receive some, that is either down to your location, or to your system setup. Digital UK's postcode checker shows a prediction of 100% probability across the board, which indicates that signal levels are likely to be high. Too much signal can also cause problems if the signals are distorted by any amplifiers in the system, including the amplifier in the TV, set-top box or PVR.
If you have an amplifier or booster, you should remove it. If not, or that doesn't help, add an attenuator to reduce signal levels, to avoid overloading the TV or box's input.
You are also expected to have a very good chance of reliable reception from Black Hill (after next week's final step there) and from Angus, while predicted levels from Durris are also high, so generally the received levels could be very high. It's worth checking that the box has tuned into the frequencies from Craigkelly and not weaker off-beam signals from one of the other transmitters. Some boxes store the first version that they find, even if it's poor, which could have happened with some of the muxes from Durris, as they're on lower channels.
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Jack: The reasoning behind the 7 dB difference appears to be:
- For perfect reception, analogue required 43 dB of signal-to-noise ratio
- For error-free reception, digital requires about 17.3 dB of signal-to-noise ratio if line-of-sight is available (20.3 dB if not)
- Planners added 5.7 dB of 'implementation margin'
- Propogation varies over time, but 99% of this variation is within 12.8 dB of the predicted signal
Adding the required signal-to-noise, the fudge factor, and the variation, we get 35.8 dB, call it 36 dB. This is 7 dB less than the 43 dB required for PAL.
The commercial multiplexes don't have to meet the PSB multiplex requirement of 98.5% population coverage, matching predicted analogue coverage, nor do they have to make their signals reach the relay transmitters, which are nearly all fed off-air (they pick up the signal from a main transmitter and re-transmit it, usually on a different frequency). Reducing the power by half (3 dB) reduces the tolerance of variation at the fringe of the coverage area by about 5%.
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Heinz, Dale: We're trying to keep up with what's going on, but the only official documentation comes from Ofcom and they seem to be following what the broadcasters do, not leading.
There is more information - from which a lot of that commentary came - in the "Digital Terrestrial Broadcasting Stations for Multiplex Licences" documents at Ofcom | Supplementary licence documents in relation to DSO . These now form part of the licences to broadcast. However, the notes are truncated badly for version 2 and fairly badly for version 3 on Mux A/SDN.
The version 3 document confirms Mux C/Arqiva A on C54 at 3kW and Mux D/Arqiva B on C50 at 2.2kW from DSO 2. Digital UK's postcode checker (which is run by the broadcasters) confirms this, but indicates that both will change mode to 64QAM 2/3 from the current 16QAM 3/4. The new mode requires about 4 dB more signal-to-noise ratio than the old mode. A doubling of power is 3 dB, so there will be a small reduction in the covered area, but not as much as if the power levels were left unchanged.
At other sites Arqiva have swapped their multiplexes A and B around, so that Arqiva B (which carries Sky Sports) gets the better channel/the one which can get a power increase earlier. Before switchover Sky Sports 1 and 2 are carried by the BBC on their second multiplex; if ArqB doesn't go to 64QAM 2/3 at DSO 2, these channels have no home because BBC B is changed to DVB-T2 256QAM 2/3 for HD channels.
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Heinz: Digital UK's predictor shows that you are well within the covered area, a prediction of 99-100% across the board, and I would say that any problems that occur at switchover are likely to be down to too much signal. This is particularly the case at Sudbury, where the peak power reduction from analogue to digital is only 4 dB, whereas at most sites it is 7 dB.
The average digital power is actually higher than analogue, because the peak-to-average ratio is much smaller for digital than for analogue. The analogue transmissions could also be, and are/were, synchronized so that the channels were not all transmitting at peak power at the same time, whereas digital transmissions cannot be synchronized in this way. You can get an idea of how digital signals combine from BBC White Paper 156, DVB-T and Voltage Ratings of Transmission Equipment at BBC RD - Publications - White Paper 156 DVB-T and Voltage Ratings of Transmission Equipment , and how that differs from analogue in White Paper 126, titled 'Co-axial Cables' at BBC RD - Publications - White Paper 126 : Co-axial cables (see section 10 on p17).
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Alan: The problem for you is that the final COM channels from Durris clash with the PSB channels from Knock More. (The underlying cause is probably the governments' decision to release channels 31 to 40, and 60 to 68, meaning less space for digital TV transmissions.)
Knock More is closer to you - 23km vs 55km - but Durris is more powerful, 100kW vs 20kW. Distance has more effect than the transmitter's power - theoretical calculations show that you should receive slightly higher signal levels from Knock More than from Durris. It does also depend on the terrain - there are hills blocking line of sight to both transmitters, but I would say the situation with Durris is worse than Knock More.
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Will: If you already have a wideband aerial, you don't need to change it. However, you're right that a Group A aerial should provide more gain, for a given size of aerial.
There's a chance that any new interleaved services could start up outside Group A. The report produced for Ofcom's review on the subject constrained the channel selections to those within or just outside the traditional analogue group, including Channel 5. You needed a wideband aerial for analogue C5, so they could have selected any channel between 21 and 60, though in fact the channel producing the best coverage from Durris was C30.
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Nick: When you say the picture is smaller, how does it compare? Does it have black bars at top and bottom? At left and right?
It could simply be that the modulated output only carries 4:3 picture information and not full widescreen, and also possibly that the channel is broadcast in the compromise 14:9 ratio. See More than just a pretty face... , which mentions (scroll down to 'Wot no AFDs?') that Sky digiboxes do not send the Active Format Descriptor to the set.
SCART can signal that a picture is widescreen using the status/aspect ratio pin 8.
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Wallace Douglas: If you have picture, but no sound, you probably have the TV set to the wrong mode. You need to make sure it is set to PAL I, System I or UK, not B/G or any other option that might be available.
I'm assuming that the satellite receiver is an official Sky box and not some other free-to-air receiver. If it isn't a Sky box, check that the receiver is also set to PAL I or UK. If it's a plug-in modulator, note that some sold by satcure.co.uk came pre-set for PAL B/G and need to be adjusted for PAL I.
TV transmissions have differed somewhat around the world, with the sound carriers at different locations relative to the video information, and sometimes different ways of encoding the sound.
If you're interested, there's a list of how the picture and sound were transmitted at World Analogue Television Standards and Waveforms .
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M
Sandy Heath (Central Bedfordshire, England) Full Freeview transMonday 20 June 2011 2:06PM
Dunstable
Adam: UHF reception can vary greatly between locations only a small distance apart, so we really need a full postcode to see the situation for you.
Taking a postcode for the centre of Dunstable (Bing Maps gives a co-ordinate of 51.8858052045107,-0.52066370844841 which nearby.org.uk translates to LU6 3SH), I get a prediction of 100% on the PSB multiplexes, 73% on Mux A, 76% on Mux C and 92% on Arqiva B. This is the estimated probability of finding a location for a rooftop aerial that would give reliable reception, at that postcode. The simplified coverage checker for consumers will show that as 'good' on all six multiplexes (the threshold is 70%).
I would start by bypassing the booster and splitter and seeing what the situation is like on each TV connected individually to the aerial. If you can get all the channels, plug the splitter in without the booster and try again. If you find that you can't get all channels with the booster, but can without, leave it disconnected. Otherwise, check that the booster has just enough gain to offset the loss through the splitter. A 4-way splitter typically drops 8 dB.
It may all just fix itself as the switchover programme completes. The retune in August changes the prediction for Mux A to 97%, while that in mid-September puts Mux C to 93% and Arqiva B to 99%. The November retune and mode change turns Mux C into Arqiva A, for which the new prediction is 99%.
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Doreen: Can you provide a full postcode, please? Reception depends very heavily on your exact location and can change quite a lot with just small changes in distance.
Does your box still show an entry in the Guide for ITV3 on channel 10? If you enter '10' on the remote, does it show NO SIGNAL, or just not change channel? If the channel is entirely missing, try retuning - some boxes retune automatically, and if the multiplex carrying ITV3 was off-air or at reduced power when this happened, it may have deleted the channel.
There is some natural variation in signal levels due to how the signal travels through the air, and over terrain and around buildings, which sometimes can cause drop-out due to either too low or too high signal levels, or higher levels of interference from other transmitters using the same frequencies.
Changes in reception can also indicate the start of a problem with your aerial system or cabling. Check that analogue BBC One is clear, or at least as clear as you remember. If not, get the system checked, although note that there is currently engineering work going on at Sutton Coldfield which may cause periods of low power and interruptions. We don't unfortunately, know how long this will go on for, as Digital UK only publish notice of works a week at a time.
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Chris: Assuming your postcode is RH5 5BH which you've put in before, you have very high probability of reliable reception, including Mux D.
You've previously indicated having problems with C66. If this happens when it's raining, the problem could be water ingress into junction boxes or cables. Higher frequencies are affected to a greater extent than lower ones. Cables are damaged by exposure to the sun over time, which can allow water to penetrate, or, if not well secured, the cable can rub against brickwork or tiles and eventually the insulation wears through.
Mux D also has the lowest signal levels of all, which is another reason it can be worse affected than other multiplexes.
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Dave: Because they're not actually comparing like with like.
It's stated that analogue transmissions require 43 dB of signal-to-noise ratio - about 20,000 times the power from the signal compared to the interference - for perfect reception.
Simulations show that error-free digital reception only requires 17.3 dB signal-to-noise ratio - about 0.27% of the analogue difference. However, this is the absolute minimum required: any lower, and the picture and sound start to break up. The broadcasters' statistics show that, to provide reliable results, the signal needs to be about 12.8 dB higher. They've also added about 6 dB of fudge factor (i.e. nearly 4x power levels), making for 36 dB in all.
This 36 dB of signal-to-noise ratio is 7 dB less than the required analogue level, so in general, levels have been set 7 dB lower than the analogue levels, or one-fifth of analogue power. This is the same right across the country, except that the south-east coast transmitters have been set higher to provide extra resilience to signals from continental Europe, or perhaps reflecting better aerial systems that send relatively less signal overseas.
Experience seems to be showing that the 6 dB fudge factor is unnecessary and levels could have been set lower. In effect, the digital coverage areas are actually larger than the analogue ones.
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Ray Reed: I'll say at the outset that I'm a software engineer rather than an electronics or RF engineer, though I did cover some electronics at university (started out studying electronics but couldn't handle the maths for Semiconductors and Opto-Electronics).
You could have too high a signal level.
Digital TV requires that all amplifiers in the signal chain are linear, or as close to linear as possible. Distortion introduced by non-linearities causes intermodulation of the individual channel transmissions making up the service as a whole. At Crystal Palace there are currently 11 services, four analogue and seven digital (six SD, 1 HD), plus one from Croydon (analogue Channel 5). The intermodulation changes the amplitude and phase of the signal from what was intended.
The digital transmissions carry redundant information from which the original data can be recovered. They also carry a further checksum which can indicate when the data recovered is incorrect. This 'outer code' can detect up to 16 bytes in error and correct 8 of them. The effect of uncorrected errors depends on where the errors fall and could cause colour errors, synchronization errors, picture and sound drop-outs. The MPEG 2 video compression scheme relies heavily on encoding only changes from frame to frame, so errors in one frame can persist for several frames.
The Confederation of Aerial Installers recommend that digital signal levels are set to 45 to 65 dBuV (some sources have 60 dBuV) for each 8 MHz channel. Ensure that your meter is measuring the power across the whole channel - for analogue, most of the power is concentrated in the carrier (especially in sync pulses) so older meters may measure a narrower bandwidth. Analogue levels should be set to 60 to 80 dBuV. At Crystal Palace, digital transmissions are currently 17 dB down on analogue, which means that setting analogue correctly should give roughly correct digital levels and vice versa. The overall signal level should be less than the maximum marked on the distribution amplifier.
I wouldn't rely on a cheap meter, they are often poorly calibrated - both in the designed range and in quality control - or don't even measure the right thing.
Intermodulation between two analogue signals tended to only cause a 'herringbone' pattern, due to the channel spacing. Digital signals had to be packed in anywhere they could be fit in, but to an analogue receiver, a superimposed digital transmission just looks like random noise - this is a deliberate property of digital transmissions, which are fed through pseudo-random processes to make them look random.
Your postcode is only 12km away from Crystal Palace. If the aerial were outside, you could theoretically get 100 dBuV at the aerial terminals for analogue channels, and 83.5 dBuV for digital. http://www.megalithia.com/elect/fieldstr.html
Neighbouring buildings can block signals, so you often get 10-20 dB less than predicted, and the tiles or walls will reduce that further. Still, I think it's more likely that your problems are down to excess signal than insufficient.
To fix the problem, I'd go back to your old aerial. You didn't need to change it. If that still gives excess levels even without the amplifier, add an attenuator. Ensure that the amplifier is only adding as much gain as you lose through the splitter - this should be marked on it, typically a four-way splitter drops 8 dB.
I suspect the change was down to the switchover at Sandy Heath in April. Digital transmissions cause more harm to each other than an analogue signal does to a digital one. While Sandy Heath is off to the side, aerials do still pick up some signal from neighbouring transmitters, and refractions and reflections within the loft space will amplify this.
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James: You are in a very strong overlap area between the Craigkelly and Black Hill transmitters, so there is a chance that your box could have decided to store a weak off-beam signal from the other transmitter when you retuned.
Check which transmitter your aerial points to - south-west for Black Hill, north-east for Craigkelly - and see Digital Region Overlap for some suggestions.
It's also worth checking that the signal levels aren't too high. If you have a booster or amplifier, you should remove it. Signal levels should be more than adequate without.
If you're using Craigkelly, and you never had a wideband aerial fitted, you will need one now as Multiplex A/SDN has moved from within the analogue group to outside it. This would apply if you couldn't get Multiplex C or D, or analogue Channel 5, before switchover.
A few boxes have problems if they pick up some multiplexes in 2k mode and others in 8k mode. Right now, all signals from Craigkelly are 8K mode, while all except the main BBC multiplex from Black Hill are in 2K mode. If you don't have BBC One, your box may not support 8K mode and, if so, will not pick anything up after Black Hill switches over tomorrow morning. As I say, some behave oddly with mixed modes so you could just try retuning after 6am on Wednesday, when everything will be in the same mode. You can find a list of some equipment that is known not to work at http://www.digitaluk.co.uk/2kequipment .
A few boxes are still around that don't support the larger Network Information Table introduced in 2008, but this is only a problem after they are retuned. If you hadn't retuned it since then, before this switchover began, you might not have encountered this problem before. You can find a list at http://www.digitaluk.co.uk/splitnit .
There are also some TVs and boxes that can't handle the number of channels now transmitted. I don't know of a list of these, unfortunately.
Craigkelly did not use the new frequency for Mux A/SDN before, so if you're using a communal shared aerial you might need to get the landlord to get the system adjusted. You might also have to look for any equipment that has an RF modulator, such as an old VCR, games console or Sky box, and check it isn't using C45.
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Ken Clark: In Aberdeen, she is likely to be using the Durris transmitter, where the second stage only resulted in the Public Service multiplexes moving to their final channel. The Commercial multiplexes had to stay on their old channels at reduced power. With Craigkelly having completed switchover, the commercial channels at Durris could move onto their final frequencies and power levels, which happened last Wednesday morning (15 June).
To get ITV3, which is carried on a commercial multiplex, back, you will need to retune the equipment in the same way as the other switchover stages.
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James McEwan: See my earlier reply to James from Falkirk! I can't do a detailed prediction, because you haven't provided a full postcode.
There is a relay transmitter at Canongate, to the north-west of Holyrood Park, which may indicate that signals from Craigkelly are poor in this area. Signals are aimed to the north-east of the transmitter, i.e. north of the park, on horizontal polarization, and to the west and the south on vertical polarization. Craigkelly is the other side of the Firth, above Burntisland.
Sometimes signal levels from the main transmitters are improved further than you would expect from the change in published levels, because the new main aerial is that much higher or has a different radiation pattern from the old digital aerial, so check for high levels. That said, both the old aerials - main and digital - were replaced by October 2010.
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Simon: Because the operators of any multiplex have to agree to any change to their licences, such as to add new transmitters, and the commercial multiplex operators have refused. They say it is not cost-effective.
All you can do is complain to ITV plc and Arqiva, who operate these multiplexes, or to the channel you want.
If they did extend their services, it would likely be only to the high-power relay stations, though Conway would probably be counted as one of these as the pre-switchover analogue power was more than 1kW.
The Public Service Broadcasters were quoted £24.7m for broadcasting from all 1,100 relay stations in 2007, while the commercial broadcasters were quoted £10.39m for broadcasting from only the 81 sites they used before switchover. Some of the costs for the PSBs would be shared if the commercial broadcasters extended their services.
It is much cheaper for the channels to be carried on satellite or cable, particularly with Sky subsidising carriage or providing subscription revenue, for subscription channels.
Because they refused the option early in the planning process, no frequencies were left free, and it may now be difficult to find any to provide the service. The coverage area for any additional services may not match the PSB multiplexes.
Depending on your location, you may find that it is possible to receive from a main transmitter - in this area probably Llanddona. If you provide your full postcode, I can check, or you can check for yourself at Digital UK - Home .
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Ron Wagg: Check the power supplies for all equipment in the vicinity and ensure that power cables are kept well away from the signal cables.
The scrolling line is likely to be interference from the near-50Hz power on the near-50Hz SCART connection from the box to the TV. If both were exactly the same frequency the line would be static, in the same place all the time.
The intermittent interference is more likely to be mobile phone interference on the satellite cable. Keep your phone well away, or replace the cables with better-screened ones. Satellite connections should always use 'satellite-grade' cable with copper braid over copper foil screening - traditional 'low-loss' coax is not up to scratch and will pick up more noise.
If that doesn't seem to help, check whether the interference is related to some motor or other electrical equipment switching on or off, for example the thermostat or central heating pump. If so, get that equipment checked.
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Nick: Well, I can only assume that the set overscans a bit more on one than on the other. No idea why it should do this, if the Sky box is sending the sync pulses at the same time on SCART as it does on the RF modulator.
My TV has zoom modes to reduce the black bars (e.g. 14:9 sent as 4:3, 16:9 sent as 4:3, which happens often on VIVA), any chance that you have a zoom feature selected when SCART is selected? Mine uses the same zoom mode for all inputs, but perhaps yours remembers the zoom setting separately for each input?
Otherwise you're probably down to hunting for 'timing' configuration options on the TV!
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Dave Dickinson: A freesat box should work with any dish pointed to the Astra 2 cluster, though it may need to be larger than usual to ensure that adequate signal is received from the 2D satellite. The 2D satellite carries most of the Freesat service (the same transmissions are included in the Sky service, they are not duplicated) and it is designed to only cover the British Isles with normally-sized dishes. The closer you are to the UK, the smaller a dish you're likely to need.
French-language transmissions come from a different cluster of satellites - looks like Astra 1 at 19.2°E. Some dishes do allow more than one LNB to be carried. You then have to set the dish up so the signals from one cluster are deflected to one LNB while the signals from the other, go to the other. It's possible, but the dish has to be adjusted more precisely. Separate dishes may be easier!
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Mike: Different equipment has different limits on what it will accept, and behaves differently if more than one transmitter is received.
Digital UK's predictor suggests a good probability of reliable reception from three transmitters: Craigkelly, Durris and Angus. They're all in kind of the same direction - Craigkelly slightly west of due north, 341°, Angus slightly east, 6°, and Durris a bit further clockwise, 20°. Aerials do have a fairly wide acceptance angle - the larger the aerial, typically the smaller the angle - so the TVs could be picking up one of the further transmitters. It's likely to be Durris, as that has the lowest frequencies, though I would have expected it to pick PSBs from Craigkelly and commercial channels from Durris.
The Durris commercial multiplexes only moved to this location on 15 June, their temporary locations were on much higher frequencies.
If the TV offers a choice of region, ensure you select Central Scotland rather than Highlands and Islands. If you can find a status screen, check that the UHF channels match those from Craigkelly, rather than one of the others. See Digital Region Overlap for other thoughts.
Check that you do need the amplifier, and if you're adding an attenuator, add it before the amplifier. Amplifiers should normally only have just enough gain to offset the losses in the splitter and cabling, if the basic level from the aerial is correct.
On pure distance alone, I would expect the signal levels at your location to be very high, but you're in a fairly deep valley, which means that you're relying on refraction over the hills. Still, excessive amplification can still cause problems.
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Bill Kett: The prediction for your postcode isn't great at the moment. It's possible that the level of interference has been steadily climbing as the switchover programme has progressed, both here and abroad, and is now too high for reliable reception.
Still, I'd normally expect break-up rather than complete failure. Check that the aerial is pointing in the correct direction and that all cables are still intact.
You say that the aerial is new. How new? Was there a guarantee? I'd recommend calling out the installer and getting them to remedy it.
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David Jackson: Presumably this was a diplexer, combining a Group A aerial pointing at Crystal Palace with a Group B or E pointing to Sudbury? There's no problem diplexing aerials together for digital services. Nothing in the chain is specifically 'digital' or 'analogue' until you get down to the receiver, and usually only the decoder stage rather than the front-end tuner.
Some boxes do get confused with a mixture of 2K and 8K mode transmissions, in the interim period between Sudbury and Crystal Palace switchovers, and it can be difficult to get some boxes to store the services you want at the preferred numbers. Most would likely store Crystal Palace services at the published channel numbers as they are on the lowest frequencies.
CP may be stronger now, but Sudbury shows a slightly higher probability of reliable reception once the switchover programme is completed. Both are ultimately good, though (except Crystal Palace Mux C/Arqiva A drops to 'variable' in 2013, possibly due to changes overseas as the UK programme should be complete by the end of 2012.)
However, you have to wait almost another year for Crystal Palace to switch over, while Sudbury starts in a couple of weeks. That said, only the PSB multiplexes change to final channels and power levels. The COM multiplexes (A/SDN, C/Arqiva A and D/Arqiva B) stay at low power from Sudbury until after Dover switches over in a year's time.
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pappyon: Usually this has something to do with the length of cable between the two boxes and the aerial.
If the aerial splitter is near the aerial itself, and the working box is on the shorter cable, signal levels may be slightly too low at the non-working box. Add a small amount of additional amplification or replace the aerial with a slightly higher-gain one, of the appropriate type. Warning: if your transmitter uses Group A, and you have a grouped aerial now, a wideband with a high quoted gain may turn out to have less gain in the place you need it.
If the working box is on the longer cable run, signal levels are probably slightly too high.
If you're splitting at the back of the living room recorder, the added drop in the cable run to the bedroom is probably too much. Try to split the cable as close to the aerial as possible. Again, an amplified splitter can result in too *much* signal - ensure that amplification only just offsets losses in the splitter. Also, amplification adds extra noise, which can be a problem if the signal-to-noise ratio is marginal.
Make sure you're using proper splitter devices, not just twisting cables together.
Ensure all cables are satellite-grade, double screened, copper braid over copper foil screen, and ensure that if you're building them yourself, that you're fitting the connectors properly.
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Ron Henshaw: Can you provide a full postcode so we can see the prediction?
You should not need boosters on any TV. It is always better to amplify as close to the aerial as possible if it is required, but unless you're in a particularly difficult location it shouldn't be. You should try to maximize aerial gain before adding amplification.
If you are splitting the signal, and some amplification is required to ensure that each set has enough signal after the split, just add enough to offset the insertion loss of the splitter and the losses in the cables.
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G Davies: You should be able to see the Neath Abbey relay out of the window - the centre of the grid square for the centre of your postcode is only 200 metres away from the centre of the grid square containing the transmitter. It's the phone tower behind the school.
Neath Abbey transmits on both horizontal and vertical polarization. The transmitter is due east of you, and transmits more signal on horizontal polarization in that direction. Make sure the aerial elements go left-to-right rather than up-and-down.
As you're so close, you could end up with excessive signal levels even though you're using a set-top aerial in the loft. These typically have little useful gain, but the theoretical received power level is about 10 times the recommended limit, roughly the gain you get from a good aerial. If you have any amplification in the system, such as a booster, try removing that first.
Your TV may have decided to store the signals from the main transmitter at Kilvey Hill, as they are on lower frequencies, or if it selects them based on quality and the Neath Abbey transmissions are distorted due to being too loud. Kilvey Hill is 6km south-west of you, just to the east of Swansea.
See Digital Region Overlap for thoughts on how to ensure you're getting the signals you want.
Digital UK's prediction for this transmitter is for a good chance of reliable service on the PSB multiplexes, but a variable service on the commercial multiplexes. The problem here is that the commercial muxes at Kilvey Hill use the same frequencies as the public service multiplexes from Caradon Hill in Cornwall. All multiplexes clash with services from Stockland Hill in south-east Devon. It looks like line-of-sight to Kilvey Hill is clear.
The raw field strengths could still be quite high from Kilvey Hill - theoretically still a few times the recommended upper limit.
With the expected relative signal strengths, I would recommend a grouped aerial to reduce the level from the unwanted transmitter. A Group A aerial, for Kilvey Hill, has a lot more gain and better directional properties than a wideband in the appropriate group, you can then add attenuation to reduce the overall levels. Neath Abbey uses Group C/D.
To reduce signal pick-up from Caradon Hill and Stockland Hill, you could try rotating the aerial clockwise so it points a bit to the north of Kilvey Hill. Aerials do have 'side lobes' in their response patterns, places where they have more gain than at others. Careful positioning can reduce unwanted signals to a minimum, though it's hard to quantify this without professional equipment. Higher-gain aerials have tighter directional response - you would need to add attenuation to keep levels down to what your TV can handle.
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Mark Aberfan Aerials: I assume the phone companies will want to site-share as much as possible, just as they do now.
The danger is that the combined signal level from the TV transmissions (wanted) and the 4G signals (unwanted) pushes equipment outside its linear region, causing distortion, resulting in intermodulation. That intermodulation creates frequency-shifted products, potentially splatting the 4G phone signal - an OFDM signal just like digital TV - onto one or more multiplexes. That will at least reduce the tolerance of interference and noise from other sources.
However, the 4G power is likely to be lower than digital TV power. If you make the coverage area too big, the bandwidth is shared between too many subscribers. Cells have to be fairly small. 800 MHz spectrum is in demand because of its penetration into buildings and the relatively lower power needed for the same coverage, not providing wider coverage (though some wide-area transmitters are needed for base coverage of relatively unpopulated areas).
I do think Ofcom are seriously underestimating the extent of the problem. It seems to be normal practice for newer aerial installations to have excess gain and often the owner has added amplification as well, thinking that this will correct any reception problems. Sometimes it might appear to have done so as by the time the amplifier is fitted, the root cause of the issue has gone away.
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Mary: 'Low Power' is relative. Digital UK's prediction for Emley Moor is 99-100% across the board, because 38km away isn't that much for even 4 kW transmissions. Indeed signal strength is more likely to be too high than too low.
You say you're on cable TV. Do you actually have the TV connected to an aerial, for Freeview? With the kind of signal strength expected in your area, it's possible that enough signal could be picked up just in cables for it to work some of the time.
If you only have the Virgin Media cable, and you want to stop paying for the subscription, you would need to have an aerial fitted. There is no free service on Virgin Media (there should be a basic free service of just the public service channels, i.e. the BBC channels, ITV1, C4 and C5, but VM are flouting the law). Even if there was one you would need a set-top box for cable transmissions, which are sent differently to Freeview, and Virgin Media are supposed to take the box away if you stop subscribing.
Some Virgin Media installers are careless or malicious and actually chop the aerial cable, preventing it from being used (happened to my sister). If it used to work before you got cable, and it doesn't now, you may find this has happened.
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Bryan McAlister: All power increases have already happened this morning, if your transmitter is back on-air. Some are still off-air as work is being completed. The status for each relay can be found at http://www.digitaluk.co.uk/when_do_i_switch/stv_central/black_hill/blackhillrelaytimes .
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Maggie Nicholson: Looking at the prediction for your postcode, chances are that you now have too much signal. If you have an amplifier or booster, remove it. Then you might need to add attenuation to bring the signals down to an acceptable level.
Based on the postcode, it looks like you're in a tower block, and using a communal aerial. If so, the system may need recalibrating and/or retuning. This may already be happening - check with your landlord or residents' association. See PARAS - Professional Aerial Riggers Against The Sharks for some thoughts.
Other possible problems would be 2K-only equipment, limits on internal memory in the box, failure to understand a large Network Information Table, failure to handle negative offsets on some equipment, or other equipment adding modulated output on a required channel. I don't expect any of these to apply to you. The first three would have shown up two weeks ago, Black Hill doesn't use any negative offsets, and modulators would normally only knock out one or two channels.
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Gerry: The SkyLink system is designed for you to plug the aerial connection into the Sky box's aerial input (e.g. RF IN). The Sky box does not actually use the input, it adds its modulated output to the rest of the signals picked up by the aerial.
Otherwise, you can use a splitter in reverse as a combiner.
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ALL: Officially the services from Black Hill were going to be off-air from midnight to 6 am. If you retuned between those times, your TV or box could have picked up signals from another transmitter, or a partially-completed reconfiguration from Black Hill.
If you're still having problems now, you should retune again first and see if the problem goes away.
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Derek Carpenter: Complain to ITV plc.
Basically they cheaped out and only bought enough delay equipment and monitoring for the six services they can fit on satellite.
Those services are:
Granada (Manchester)
Central West (Birmingham)
Wales
London
Meridian South-East (Maidstone)
Yorkshire West (Leeds)
You get the version that is part of the same advertising sales macro-region that you're part of. For you, this is the 'West' macro covering the old HTV West, HTV Wales and Westcountry regions.
The Meridian South-East service is transmitted to the entirety of the Meridian and Anglia regions (the South East macro), while Tyne Tees and all of Yorkshire get Yorkshire West. I'm not sure whether Border gets Yorkshire West or Granada. All of Central gets Central West.
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Colin: Check that your box hasn't decided to tune into Stockland Hill instead. Some just store the first version of the channels that they find, and Stockland Hill is on lower frequencies. The prediction for the commercial muxes from Stockland Hill is variable or poor, and the aerial will pick up less signal from that direction, but it could still be enough to detect the services. Changes at other transmitters, particularly Ridge Hill which now uses the same frequencies, could have made it worse. See Digital Region Overlap for some thoughts on how to fix this.
"I have the biggest aerial one can buy."
That could be your problem. Digital UK's postcode checker shows a prediction of 99-100% across the board, and it's usually a bit pessimistic.
There's a slight terrain restriction which will reduce levels slightly compared to clear line-of-sight. Line-of-sight levels are expected to be 80 dBuV max, on Mux 2/D3&4 (C54) and minimum 69.6 dBuV on Mux A/SDN (C62). These figures include 10 dBd of aerial gain, which is what Digital UK use in their predictions. The recommended upper limit, to avoid intermodulation, is 65 dBuV.
If you have any amplification, you should remove it. You will probably also need to add some attenuation to bring levels into spec.
As far as the TV licence goes, it's your licence to own and operate a TV. That's it. You have to pay the full rate if you own a colour TV. You can still pay a reduced rate for a monochome TV, bizarrely. The funds from the licence fee go to the BBC only, so even if it were based on reception - which it is not - I can't see that you'd be entitled to any discount if you were getting all BBC services.
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Donald MacLeod: Very few Freeview boxes put their output on the aerial cable. You would need one with an RF modulator. Your older box may have had one, most new equipment doesn't.
It is possible to buy separate RF modulators that just plug into a SCART socket on the Freeview box.
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John Lees, andrew mark: The BBC has never provided a West-region service from Ridge Hill or its relays. Given the cutbacks they are having to make, I doubt they would want to do so now.
ITV only started the West service after breaking up the older Central South sub-region in 2007, primarily to put Oxford in with Hannington to form 'ITV Thames Valley'. They put Ridge Hill in with Central West from Birmingham as the served area was considered too small for a separate news service. (Ironically, ITV Thames Valley has ended, and Oxford and Hannington viewers now get the Southampton service.) The three-way divide of Central's news service was a condition of the 1991 licence.
It's more likely that regional services will be closed down, though the Prime Minister - whose constituency is near Oxford - has put pressure on to keep his local service.
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Sean: Did it work before, or have you only just bought this TV?
The HD signal is at half the power of the other transmissions, but require the same signal-to-noise ratio as Mux 2, which carries ITV1 and C4 plus other related channels. It is transmitted from Lichfield, where analogue C5 comes from, rather than Sutton Coldfield, and aimed only into Birmingham to reduce the risk of interference to anyone else. They are also on a lower frequency, lower than the traditional analogue group, and your aerial might not pick up as much signal as for the SD multiplexes.
We really need a full postcode to see what the situation might be for you.
At switchover, at the end of September, the HD transmission moves to Sutton Coldfield, where it will be on a clear channel, broadcast in all directions, and at the same power level as BBC One (etc), as well as being within the range of all UHF aerials that have been used here. (It replaces the BBC Two analogue service.).
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Robert Dawson: 'DV3' is probably the stylised DVB logo from DVB - Digital Video Broadcasting - Home . The model number is likely to be on a sticker on the back of the unit.
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Bob: Red Button streams are up at 11954 MHz, on Astra 2B rather than 2D where all of the BBC's main channels live. It's possible that something was blocking the 22 kHz tone that the TV sends to the LNB to tell it to switch to the upper band.
If you are feeding the TV from another satellite box's 'LNB OUT', the other box will have control over the high/low and horizontal/vertical selection signals if it's on rather than in standby, or for recorders it may take control if recording two channels at once. If you have split the cable feed from the LNB to more than one box, either only one leg of the splitter will allow the control signals to pass up to the LNB, or if both boxes are on at the same time, the LNB can get confusing signals. Ideally you would run separate cables to separate outputs on the LNB for each input on each box or TV.
If you have some DiSeqC equipment, it may be blocking some of the selection signals, as it uses the same features. The TV might have a normal/DiSeqC selection mode - you might have selected the wrong mode. DiSeqC sends 22 kHz pulses for selection of different dishes, while the LNB requires a constant tone.
Of course it could simply be that the LNB's 22 kHz tone detector has failed, or the tone generator in the TV has failed.
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Ray Reed: You say this is happening on multiple TVs, fed from one distribution amplifier. Have you checked the amplifier's power supply? http://www.wrightsaerials.tv/articles/whatsat-201006.pdf
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Shuggy: In Glasgow, you would probably be using the Black Hill transmitter. All services were reshuffled to different frequencies on Wednesday morning (before 6am) as the analogue transmissions were turned off.
Everyone is recommended to do a full reset on both switchover days, and any subsequent major retunes involving frequency changes or mode changes, because some boxes will not discard previous channel information even if they detect new locations for those channels, or don't find the channels during one sweep.
If it's just a case of new channels starting up on an existing multiplex, the 'automatic scan' feature should work fine without discarding anything already known. You may still end up with channels that have closed in the EPG, and if a previous channel number is reused for a new service, or a channel moves to a different number, your box might not pick up the change or put the channel at the wrong place.
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R H Bevan: Digital UK's tradeview predicts that you should get the two multiplexes you do now, plus Mux A/SDN. Mux C/Arqiva A and Mux D/Arqiva B will stay on low power until after Tacolneston switches over in November, as their allocations clash with low-power services at that transmitter. Once the power is increased, the predictions are over 90% probability of reliable reception for all six multiplexes.
Note that it is possible to have too much signal as well as too little.
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Norman Smith: In OX25 you're likely to be using the Oxford transmitter. Mux 2, which carries those channels, is right at the top of the frequency range. Losing this often indicates that there is a problem with the cabling.
Has it been raining there today? Does it often coincide with wet weather? If so, it's likely that there's a leak somewhere allowing water to penetrate the dielectric of the cable - the insulation between the inner core and the outer screening - which reduces the ability of signals to travel along the cable. Higher frequencies suffer more loss than lower ones.
Check the seals on all external connectors and any boxes such as a masthead amplifier. The aerial should have been oriented so that the open side of the connection box, if any, faces down, so that any water that does get in can drain out. Also check that the cables are all well secured and haven't been rubbing against tiles or brickwork, as you start to get problems when the outer insulation wears through.
Finally, the outer insulation perishes with exposure to sunlight. They only last so long. If they've been up for more than 10 years they may need replacement.
If the dielectric is foam, it could be saturated and there's little that can be done to dry it out. If it's air-spaced, it should dry but water can run down it to the equipment at the bottom! There might be a loop where the cable enters the house, which could be full of water, which probably won't go away.
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Colin Tough: Durris commercial multiplexes now use the same frequencies as Knock More's public service multiplexes, and the Digital UK predictor shows that this co-channel interference is severe enough to stop you getting them from Durris.
The prediction for Knock More PSBs is actually slightly better than for Durris PSBs, and the Knock More COMs prediction is also good. You should be able to get a reliable six-multiplex service from Knock More.
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LF: If the aerial points to Craigkelly but it decides to tune into Black Hill, it probably indicates that the Craigkelly signals are too distorted to use. You should expect to get very high signal levels anyway - if you have any amplifiers or boosters, you should remove them. That might still leave you with too much signal, in which case you should add an attenuator.
Older boxes were often calibrated to the maximum possible signal from one multiplex - maximum safe levels (avoiding distortion) are often way below 100%. On my Humax box it's actually about 50%. I can't find a spec for the input range on your Pioneer box.
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Justin MacNeil: As far as we know, there are no faults on the transmitter. Can you provide a full postcode so we can see where you are?
It's common for viewers to have too much signal after switchover. If you have a booster, remove it. If reducing signal levels doesn't help, check with your neighbours to see if they can get HD signals, and if they can't either, use the BBC reception page at BBC - Reception problems .
As far as the first analogue channel to go is concerned, at main stations, the transmitter that is switched off/switched mode* is whichever the BBC A multiplex replaces, which was indeed C4. However, in cases where this is not BBC Two, the channel whose transmitter was switched off is moved to the BBC Two frequency for the two week changeover period.
That is, BBC Two closed down, C4 moved to C26, then BBC A started up on C29.
For West Linton it's likely that no change was actually required, because the same change (BBC A launching on C4's frequency, C4 moving to BBC Two's frequency) happened at the upstream transmitter, Penicuik. Faults at that transmitter, or the main transmitter, Craigkelly, would impact West Linton as well. Again, no problems have been reported.
* Largely the technical switch-over happened several months ago, and the old analogue transmitter or transposer was replaced by new dual-standard equipment, which is then switched over to digital operation on the actual switchover days.
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Wilf: Yes, it is encrypted. You need a Top-Up TV or BT Vision subscription to watch it.
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Percussim: Tennis took priority as two British women got through, as I understand it. Red Bee Media (who run playout for the BBC) don't always get the EPG data updated, or some boxes don't update if the programme ID doesn't change.
On other platforms, interactive streams don't even appear in the guide or provide now/next information. Me, I like being able to record the F1 Forum.
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Mark A.: Well, some advertising regions of Channel 5 are only available encrypted, but C5 don't do any regional programming. It just means you only get London advertising on Freesat or other free-to-air receivers.
I don't see why anything going free-to-view should require new cards. They should only issue new cards if the encryption scheme for the whole system is compromised, in which case you would lose access to all encrypted channels (free or subscription) if you didn't get a new card.
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Stewart Filshill: I'm not sure if all the boxes have a built-in RF modulator. If they do, you can just connect up an aerial-type cable from the box's RF output to the second TV. You just need the plain push-in 'Belling-Lee' connectors. I would recommend satellite-grade cable anyway.
You then tune the analogue tuner on the TV into the UHF channel configured on the V Box. You can only watch the channel selected on the V Box, so you would need a remote control extender as well.
If the box doesn't have a modulator built-in, you can buy an RF modulator that plugs into the box's SCART socket.
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Ruth: Check that the SCART cable is properly plugged in? If you're using an HD box with a DVI connection to the TV, the audio would need to be carried on a different cable - again, check that it's properly connected. HDMI cables carry sound on the same cable as the picture.
If you're using an RF modulator, and tuning in a channel on the TV to the box, ensure that the box and TV are both set to PAL I/System I/UK mode.
Also check that the box and TV are not muted, and if the box remote has a separate volume control, check that the TV and box volume controls are set appropriately. I set the box's volume control to maximum and control volume from the TV remote.
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Penny: Digital UK's prediction for you is very good across the board, so you really shouldn't be having problems. Some people found that the replacement aerial at the transmitter resulted in *more* signal than they had previously, and therefore had to remove boosters and/or add attenuation.
Oxford gets ITV Meridian news ever since they closed down the short-lived ITV Thames Valley service in 2009.
If it's only Mux 2 that's affected, it could be a cabling issue. If water has got into the cable, the loss in the cable increases, and loss at higher frequencies is greater than at low ones. This can happen if an outside junction box, masthead amplifier, or the connection box on the aerial is not properly sealed, or if the insulation on the cable is damaged, either by rubbing against brickwork or tiles or simply perished due to UV exposure. Cables should be properly secured about every 15cm with cable clips as they travel over tiles and down walls, they should not be able to move.
You could also be suffering from impulse inteference, which is more of a problem in the 64QAM mode used by Mux 2 and Mux A. Check whether the problem occurs when a thermostat or motor switches on, for example central heating pump or hot water heater. If so, get a heating engineer to check the pump. Mobile phones can also cause problems - keep them well away from the TV and cables. Better-quality cables (usually termed 'satellite-grade') are less susceptible to picking up interference.
At switchover, you must do a full reset on both days as the channels are all moving to different frequencies - they replace the analogue transmissions. Analogue channels are completely switched off - it is all digital from now on.
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Roelof Kramer: Digital UK's predictor reckons you have a slightly better chance of reliable reception from Oxford than from Hannington. While there is a hill blocking line-of-sight from Oxford, there is actually also one blocking line-of-sight from Hannington, it's just further away (Thurle Down, north-west of Streatley).
It is possible to have too much signal. Many people specifying new equipment add amplification completely unnecessarily. I would start by bypassing the masthead amp, and see what the results are.
A professional installer would use a strength meter indicating the Modulation Error Ratio - an indication of how much the signal is distorted from the ideal - to decide what size aerial to use and determine whether any amplification was needed. Digital UK's predictions are based on 10 dBd of gain from the aerial and 3 dB of loss in the cable.
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Hal: For communal aerials, check with your landlord or agent, or the residents' association. See PARAS - Professional Aerial Riggers Against The Sharks for more suggestions.
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Steven C: Did you get all the BBC channels between the first stage on the 8th and the second stage on the 22nd? If so, your box is certainly 8K-capable.
Did you retune on both days? All the digital signals moved to new frequencies, the PSB channels taking over the old analogue frequencies (which were the best allocations in this location). You would need to have done a full reset, also called a first-time installation, a full retune or a default setting, to ensure that the box forgot about the old location for the channels. Some won't save channels that they already think they know about.
Many people find that they have too much signal after switchover. If you have a booster or amplifier, remove it. It shouldn't be necessary any more (though you haven't provided a location, so I can't check). Signal levels might still be too high even after this, you can add an attenuator to reduce them further.
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John Fisher: Satellite tuners need two connections as they aren't just inputs. They actually carry some control signals back to the low-noise block converter (LNB) on the dish, which tell it whether to select low or high range, and horizontal or vertical polarization (there are two receiving elements, one for each polarization). Each tuner in each receiver has to be able to individually control these settings, for its connection, to be able to access all the channels.
UHF aerials are completely dumb devices. They don't do any frequency conversion, and they are installed in one polarization, whichever is appropriate for your local transmitter. Therefore you can split the connection as many times as you like (though you do lose some signal on each split). The receiver just splits the signal between the two tuners internally.
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Mike O'Pray: In your area, Digital UK's predictor says that you won't get anything much on Mux A/SDN and Mux C/ArqA because the channels from Sandy Heath clash with two of the analogue channels from Sutton Coldfield. However, ArqB is expected to be OK - high probability of reliable reception - *if* you have the right aerial and the system is in good condition.
On 31 August, Mux A/SDN moves to a different temporary frequency, C31, after that is released by Waltham. This should then be clear enough to receive reliably.
On 14 September, Mux D/ArqB moves to its final frequency (C48) and power level. Mux C/ArqA then takes over Mux D/ArqB's current frequency. Again, that puts the prediction for all services over 90%.
If Mux A and Mux C are working reliably at the moment, or at least more reliably than Mux D, there is a different problem. Honestly, it's easiest if you call out an installer to check the levels, the connections, the cables, etc.
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James Donnelly: The Chelmsford transmitter has only ever provided analogue Channel 5. Your other analogue signals, and any digital signals, will be coming from somewhere else.
I believe Chelmsford UHF TV transmissions will be switched off completely when Sudbury is switched over, despite Chelmsford technically being a relay of Croydon. I'm not sure what purpose the Chelmsford C5 transmitter serves - possibly the fact that Sudbury's C5 transmitter was one-fifth the power of the other four channels meant that another transmitter was needed to serve this area, if the aerial was pointed to Sudbury.
Croydon's transmission power for C5 is the same as the analogue power level for the other four channels from Crystal Palace.
The prediction for your postcode from Sudbury is for reliable results on the PSB muxes (Mux 1/BBC A, Mux 2/D3&4, and Mux B/BBC B/HD) and Mux A/SDN, but variable, poor, or no prediction for Mux C/ArqA and Mux D/ArqB, immediately after switchover. This will continue until after Dover and Bluebell Hill switch over next June, when the Sudbury COM muxes move to final channels and power levels.
From Crystal Palace, all multiplexes are good *now* except for Mux 2 and the early HD service, which are both shown as variable. At switchover in April, everything goes up to good, over 95% probability.
The ultimate predictions are about the same from both transmitters.
If you're currently using Crystal Palace, don't bother retuning in July. Nothing changes for you. CP will get to its final configuration slightly sooner as well. Look out for adverts for the London TV region switchover, rather than Anglia.
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Briantist: I believe the switch-off date for Chelmsford should be 20 July 2011, not April 2012, based on Ofcom's latest Digital Switchover Timetable at http://licensing.ofcom.org.uk/binaries/tv/sup_dso/dso-timetable-v2.pdf .
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Mr R Pierrepont: While there is ongoing engineering work, it should not prevent analogue reception. They are only supposed to reduce power by half (3 dB) if there is any reduction, though some interruptions are possible.
Given what you say, I would check for a broken or disconnected cable somewhere in the system.
The notification of engineering works has been very poor all round, at all sites. Unfortunately Digital UK only publish the information - that they are given by the transmitter owner/operator, Arqiva - a week at a time, so we really don't know how long it's going to go on for.
The TV licence is for owning a TV and therefore you are not entitled to any rebate.
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Mr K P Brady: Does the problem happen on all channels, or only some? If all channels, it could be a case of impulse interference or electrical noise. Check whether the problem comes and goes as the central heating or hot water thermostat goes on and off, or a pump goes on and off. If so, get a heating engineer to replace the thermostat or the pump.
The aerial could be pointing at Dallington Park, less than a mile to the south-west, or
Sandy Heath itself, which is slightly south of east. If using Dallington Park, the aerial elements should run up-and-down rather than side-to-side, as they should for Sandy Heath.
If you're using Sandy Heath, and only some channels are affected, this could be expected at the moment. Channels carried on Multiplex A, C and D are currently showing no prediction for NN2 6BU, meaning they're not expected to be reliable, though your box may still be able to detect them well enough to store the location. We need a full postcode for a better prediction.
Dallington Park doesn't even carry these multiplexes, and there is no plan to ever carry them. Depending on the exact aerial and location, they still might come through strong enough from Sandy Heath to be detected - but not reliable - if the aerial does point to Dallington Park.
If using a shared aerial, contact the landlord or agent. See also PARAS - Professional Aerial Riggers Against The Sharks for other ideas of who to contact.
You can also replace the cables to reduce the pick-up of noise. If the TV connects to a wall aerial socket, you can replace just the 'fly lead' that does this last step. Try Online Satellite/TV/FM/DAB Cable, Leads and Connectors sales. . The wall socket might not be properly screened - this would be a job for the landlord if this is a communal system. Finally, it's recommended that if the cables are replaced, that 'satellite-grade' cables (with dense copper braid over copper foil screening) are used, to minimize noise pick-up.
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Nicks: As text services, Rabbit and Gay Rabbit take very little space. Certainly not enough space to provide even one TV channel - possibly not enough to even carry one radio station.
The ITV1 +1 and Channel 4+1 channels are the most wasteful on there, but the infrastructure for carrying regional content only exists on D3&4 - they would have trouble providing regional variations (minimal as they are: on C4 just the advertising is regional) on a commercial multiplex.
Legally, the ITV companies and C4 are required to carry the regional ITV service and Channel 4, Channel 5 and S4C in Wales. After that they are permitted to carry whatever *of their own services* they like on their half of the multiplex.
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Jo Drury: It comes down to money. The commercial multiplex operators didn't want to spend any more on transmitting from any additional sites. The regulator had been prepared to negotiate for 200 sites (currently, the commercial operators broadcast from 81 sites) in the international co-ordination meeting in Geneva in 2006, but the operators declined the option.
The Aldeburgh relay may not be your best option in this area, though as you say the coverage area is quite large. If you provide a full postcode we can check whether a six-multiplex service is available from another transmitter.
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michael: BBC Devon is required to be, and is already, carried on the Exeter and Torbay (East Devon) and Plymouth ensembles. Receivers can use channel information to roam between DAB ensembles in the same way they use RDS to roam between FM transmitters.
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Michael Lancaster: Permanent until switchover next April.
In fact the power level is not low. It's the same as the other multiplexes. However, because they use a different mode, they require effectively twice as much power as the other multiplexes to provide the same coverage. The reason for this is historical.
After switchover, all SD multiplexes will use the same mode. The HD mux uses a different mode entirely, which requires about the same power for the same coverage area, so all multiplexes will be equal from Crystal Palace as all have the same power level.
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David: This site's predictions are unreliable, because it doesn't have knowledge of all the transmitters' radiation patterns, and doesn't have detailed terrain information. Use Digital UK's postcode checker, which is based on the BBC's 50 years of knowledge of how UHF signals travel across terrain, and computes interference from every other transmitter in the country.
It looks like you have clear line of sight to both Sudbury and Aldeburgh, so I'm guessing that the poor projected result for Aldeburgh is either down to the radiation pattern, or due to interference from Crystal Palace, which uses the same frequencies. From November until April, Aldeburgh BBC A will clash with ITV1 from Crystal Palace, while the other two multiplexes clash with low-power multiplexes at CP (though 'low power' at CP means 20 kW). After CP's switchover in April, they will clash with two high-power multiplexes.
You should get a solid PSB service from Sudbury after switchover, but the three commercial multiplexes (A/SDN, C/ArqA, D/ArqB above) will stay on their current channels with little change in power until after Bluebell Hill switches over next June. The prediction, from 20 July, for SDN is variable while no prediction is offered for ArqA and ArqB. After the channel change on 27 June 2012, the prediction for SDN and ArqA is good, but ArqB remains variable. A reception change is shown in 2013 which will drop the COM muxes to variable - this may reflect switchovers on the continent, which I believe DUK always show in 2013, whenever they really happen.
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David Hutson: We can't really offer any detailed advice without a full postcode.
For best results from Rouncefall, you should use a Group B aerial oriented so that the rods run up-and-down rather than side-to-side. However, the transmitter also provides a fill-in function for Sudbury PSB multiplexes - Sudbury and Rouncefall form a 'Single Frequency Network', where the transmissions from both are timed carefully so that in the overlap area, the signals largely reinforce each other. If you're in this overlap area, you should probably aim your aerial at Sudbury as that transmitter provides a full service.
Rouncefall will not transmit the three commercial multiplexes, Mux A/SDN, C/ArqA and D/ArqB. You will need to use a main transmitter for those.
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Peter Stonebridge: There is no standard way to access digital text and not all channels carry it. For BBC channels, press the red button on the remote. For ITV1, C4 and C5, press TEXT.
Your TV may show some indication that text or interactive applications are available on the channel. My Humax box shows an 'MHEG' indicator.
Subtitles are always accessed using the dedicated subtitles button on the remote.
Poor signal quality could lead to the MHEG data for the text service not all being decodable, though I would expect you to get some picture and sound break-up as well. If quality is right at the top of the so-called 'cliff edge' you can get poor picture quality without actual break-up, and there might be problems with MHEG at this quality level as well, but it's a very narrow range at which this happens.
DUK predict that your reception of the BBC mux is currently variable. It should improve to 'good' next week.
Do be aware that it is possible to have too much signal as well as too little, and users of Sudbury will be particularly likely to end up having too much signal as the post-switchover digital power is only reduced slightly from analogue, while much larger than pre-switchover digital levels.
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Tony: Yes, the prediction at that location from Black Hill is currently shown as poor. It is expected to improve next year, possibly when the Tyne Tees region completes switchover.
Bridge of Allan only provides three multiplexes, but the probability of reliable reception is shown as good from all three.
You're likely to need a different aerial to use the relay. It transmits in Group A, which wideband aerials are relatively weak in, so a grouped aerial is advised. An existing Black Hill aerial would be Group B. The aerial would also need to point at the transmitter, and the aerial elements need to run up-and-down rather than side-to-side (vertical polarization rather than horizontal).
The predictor also shows that a reliable three-multiplex service should be available from the Craigkelly transmitter north of Edinburgh, though you'd get the Edinburgh STV news service rather than Glasgow. You need a wideband aerial for all six multiplexes, though the prediction for the commercial multiplexes is poor.
Aerials are designed to reject signals from the wrong group, from other directions, and from the other polarization, so it's likely that there is too little signal to just tune into one of the other transmitters.
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Jenny: Or indeed on the Belmont transmitter page - "Hull" is a radio transmitter only.
The predicted coverage is excellent, there are no reported issues at the transmitter, and no planned engineering work this week. Check that all cables are intact and connected properly, including the connection to the aerial. Do a visual check to ensure that the aerial is still intact and pointing in the right direction. It should be pointing roughly south-east for Belmont.
There is engineering work at the Bilsdale transmitter, for north Yorkshire/south Teesside, though it transmits the Tyne Tees service rather than Yorkshire, so you're not likely to be using it.
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Den: The satellite footprint diagrams for the Astra 1 cluster at 19.2°E show a 60cm dish should be enough. Go to Satellite Fleet - SES ASTRA and click on the satelites in the 19.2°E column.
Any free-to-air receiver will be able to display any channels transmitted free-to-air. See Astra 1H/1KR/1L/1M/2C at 19.2°E - LyngSat for the list. A UK Freesat receiver should do the job, you will need to use the Other Channels feature to tune in the services you want. If equipped with the DiSEqC feature, you can hook up a DiSEqC switch and connect dishes for both the Astra 1 cluster, and the Astra 2 cluster at 28.2°E which carries the UK channels.
If you only want the German, Austrian and Swiss channels, other free-to-air (non-Freesat-branded) receivers are available, or some Freesat receivers have a non-Freesat mode.
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Andy K: The FOXSAT-HD box is a satellite-only box. You can't use it with terrestrial broadcasts like Freeview and Saorview.
A conventional Freeview box sold in the UK won't work with RT 2 HD transmissions, because they generally don't support MPEG-4 AVC. A Freeview HD box would work as it does support MPEG-2 and MPEG-4 AVC.
Saorsat will be carried on the Eutelsat KA-SAT satellite, orbiting at 9°E - a long way from the Astra 2 cluster at 28.2°E. You will need a separate dish for this service.
You should be able to use the FOXSAT-HD to watch Saorsat channels, as it claims to support the mode used, and you should be able to connect both dishes to the box via a software-controlled switch, as it supports DiSEqC. It may even support a motorized dish as the manual claims it supports USALS, one method of positioning the dish, though I think separate dishes would be cheaper than a motorized dish.
The manual is a bit sparse on detail of how exactly to set up multiple dishes, though.
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Daniel Peake: Have you just moved in the last week?
The last Scottish analogue transmissions were switched off last Wednesday morning. You will need to do a full retune on your TV if you haven't already. It might be called Full Reset, Default Setting, or First-Time Installation, and it might be under the Software Update menu rather than the tuning menu. Add Channels is not enough, you need it to completely remove everything it previously knew about where the channels were.
TV Re-tune may have a guide for retuning your TV, or a copy of the manual.
It's possible that your TV cannot handle the 8K mode used for post-switchover transmissions. Check whether it's on the list at http://www.digitaluk.co.uk/2kequipment , and check with Philips whether any software/firmware updates are available.
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Michael: Whether you are affected will depend on exactly where the 4G transmitters end up being sited, and how powerful they are (how large an area they are intended to service), and the aerial group and polarization of your target transmitter.
The problem that will occur will be intermodulation, which is caused by having too much signal overall. Transmitting the 4G signals in a band that many aerials are *designed* to pick up well (Groups C/D, E and Wideband) means that, when the 4G signal is added to the TV transmissions, it could cause distortion in amplifiers and/or in the receiver's front end (which contains an amplifier). That distortion results in frequency-shifted copies of each transmission appearing as well as the original, which when added together, result in too many errors to be automatically corrected.
If you are using a transmitter that uses horizontal polarization, which most of the main transmitters do, you are less likely to be affected, as the 4G transmitters are expected to be using vertical polarization. Aerials pick up much less signal from the opposite polarization (Digital UK's predictor conservatively assumes 16 dB less, about 40x, most real aerials are better though it varies across the frequency range).
Vertically-polarized aerials generally have a wide acceptance angle in the horizontal plane, that is, signals arriving to the side of the aerial. If you're using a relay, you're more likely to be affected.
People using a transmitter that transmits in Group A or Group B should use a Group A or Group B aerial. In Group A the gain for a grouped aerial is far better than a wideband, for the same size aerial. If your transmitter uses Group A *and* Group B, a semi-wideband Group K covers both groups but cuts off well before reaching the 4G frequencies. Often Group K aerials are sold as Group B or Group B/K.
If you start to have problems after 4G services start up, the first step would be to remove any amplifiers you have, or turn them down, depending on whether the intermodulation is happening in the booster or in the receiver itself. If that doesn't help, add an attenuator to reduce signal levels.
I suspect Ofcom are saying that filters may not help if your transmitter uses C60, because filters steep enough to cut off all of C61 while avoiding C60 would need to have many tuned elements and are likely to be expensive. You would only need a filter if the received signal strength from the 4G transmitter was substantially higher than from the TV transmitter. With the clearance programme still in the early stages of planning, it's hard to say exactly who would be affected.
I do think their 30,000 homes is likely to be an underestimate, due to the overuse of extra-high-gain wideband aerials (frequently where a smaller grouped aerial would have delivered more gain, and where high gain wasn't even necessary) and viewers' tendency to add a booster when any reception problem occurs.
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Michael: I see from your previous posts that you're using Waltham. This is mostly a Group C/D transmitter but SDN will be transmitted down at C29, Group A, so you do need a wideband aerial. When the transmitter switches over at the end of August, I would recommend removing any boosters at that point.
Digital UK's trade predictor already shows a prediction of 100% across all six multiplexes, so you're likely to have problems with too much signal at switchover if you do have a booster, or a high gain aerial.
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Justin MacNeil: Each device usually adds a small amount of amplification to offset the insertion loss of the device itself, and sometimes a little more to offset the expected loss in the cable. That amplification adds additional noise, which can cause problems. Also, each amplifier could be overloaded, introducing distortion, and cause intermodulation problems, or the level could be too high when it reaches the final device in the chain, again causing intermodulation.
If the device doesn't actually tune into the signal from the aerial, and you're not using the RF modulation feature, it's better not to include it in the chain. I have to admit I've not heard of Blu-Ray players with an RF modulator before!
You also need to check that any devices with an RF modulator are set to use a free channel. You should avoid using any channel that is 1, 5 or 9 channels above any transmissions that you want to receive. (N+5 and N+9 cause beating problems, while RF modulators commonly don't suppress the lower side-band as real TV transmitters do, which then ends up on top of the channel below.).
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John Child: The BBC recently changed their HD transmissions to use a new mode. Try unplugging your Freesat receiver for 10 minutes, and plugging it back in. If that doesn't help, see if there is a Retune option somewhere in the menus.
Receivers are supposed to pick up the changes from the information carried on the Freesat EPG transmissions, but they don't all seem to be doing this properly.
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Dee: In this particular case, the Sandale transmitter and its coverage area should no longer be shown, as it no longer broadcasts TV signals. It was formerly used for the BBC's Scottish service.
ukfree.tv was originally designed for pre-switchover Freeview and very few of the relays show up. As far as the prediction system here goes - which doesn't have as much detail as Digital UK's - Haltwhistle only covers a couple of pixels and they're all predicted to be served better by something else. A particular weakness of this site's system is that the terrain data is very coarse, so it can't tell that - in this case - Cold Fell is blocking reception from Caldbeck.
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Mike Gallimore: Digital UK's predictions are the exact opposite of what you're saying. The prediction is for extremely good chance of reliable reception from Mendip, but poor or variable for Hannington (South) and Stockland Hill (South West).
This tends to indicate that signal levels are too high overall. If there's a separate amplifier included in the chain before the distribution amplifier, remove or bypass it. If not, or that doesn't help, turn down the distribution amplifier, and/or add an attenuator between the aerial and the distribution amp.
If the distribution amplifier is separate from the splitter, remove the amplifier. If not, consider replacing the distribution amp with a passive (unpowered, unamplified) splitter.
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Phil Harwood: There is a fault shown on the Marlborough transmitter page on Sunday between 1:44pm and 4:46pm. It's possible that the problem occurred earlier and the BBC only found out about it at 1:44pm.
No maintenance work is currently happening at Hannington, as far as we know. Nothing was planned for last week and nothing is planned for this week.
We need a full postcode to identify which transmitter you might be using, and what the problem might be.
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Elizabeth Forsyth: Find out where the infra-red receiver for the TV is. There might be a little 'IR' symbol next to it, or it might be a visible glossy plastic window. Check that there's nothing blocking the path for infra-red light to pass between the remote and the TV's IR sensor. Also check that the IR sensor is clean, it's common to get fingerprints over them.
If none of this helps, you will need to get the TV serviced.
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Tosh: The predictor is based on 10 dBd of aerial gain (middling - XB16E has 11-15 dBd) and 3 dB of loss in cables (high - WF100 is rated at 15-18.3 dB per 100m, which if linear would take about a 15-20m run to drop 3 dB). It's also based on a maximum of 16 dB of rejection of signal from behind and to the side, an acceptance angle of about 40° (20° either side of the middle), and 16 dB of cross-polar rejection - rejection from the other polarization, so - if using Sudbury - rejecting vertically-polarized signals from the relays. Again, real aerials will beat this, though the exact amount depends on the frequency and angle. Larger aerials will generally reject more unwanted signal and have a narrower acceptance angle.
Therefore, the predictions can be quite conservative. Still, a prediction of 'poor' or 'nothing' is likely to indicate a problem.
Masthead amplification might be useful if the issue is simply that the signal will be too weak, but it's more likely that the problem will be co-channel interference.
The Rouncefall mast will use the same channels as Sudbury for the PSB services, timed so that for most people, the signals will arrive within the 'guard interval'. This idea - called a Single Frequency Network - reinforces the signals, but only if the timing is right. If it isn't, it stops the receiver decoding it completely. This may be why, for CM9 4TT, Digital UK predict poor reception for the PSBs but good or variable for the COMs. Again, it will depend on exactly how your aerial behaves - in this case it's the polar response of the aerial (angle to transmitters) that is important.
For that postcode, the trade predictor reckons Rouncefall should start out good but deteriorate next year, presumably as Tyne Tees switches over or possibly continental transmitters, while it's expected to get more reliable results from Dover!
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David Reid, alan denholm: No problems are currently reported, click the 'BBC Reception test' links next to your messages and follow the wizard to report the problem.
Some viewers have found that they have too much signal after switchover. If you have a booster, try removing it, or try adding an attenuator instead.
Also check that the TV has tuned in the correct transmitter - David, you are also predicted to get good results from the Dunoon relay, and alan, you from the Rothesay Town relay, which Digital UK are showing that you're practically on top of.
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Graham Powell: To receive HD signals right now, you will need a Group K or wideband aerial. A newish Group B aerial - made in the last 15 years - should have some gain down at C34, but the results are likely to be poor. An older Group B aerial, not designed to receive Channel 5, probably won't pick up much down at C34.
The HD transmissions actually come from Lichfield, where Channel 5 analogue comes from. If Channel 5 analogue is poor, HD probably will be as well.
At switchover, all services move into Group B, so you should *not* need a new aerial. The HD multiplex moves to Sutton Coldfield, and takes over BBC Two's current analogue frequency.
All relays will carry the HD service. For reference, the broadcasters call this relay Kidderminster.
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Mark A., gareth: While only 81 of 1100 transmitters provide six multiplexes, those transmitters serve all but 8.5% of the population. The situation is worse in Wales, with 34% of the population not being served by any transmitter that provides the commercial multiplexes.
Channel 5 is carried on the PSB2/D3&4 multiplex and is available from all transmitters. There are a tiny number of new relays where some multiplexes don't start up until after the official switchover date, but these are generally ITV-only relays like Derby, where D3&4 *will* start on the official date.
Ofcom's current switchover timetable says that Tyne Tees and Ulster - the only remaining regions for which dates have not yet been published - must be completed by the end of 2012.
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Ian Hill: The card in the box contains the decryption keys necessary to decode encrypted subscription and free-to-view channels. If you take the card out you won't get the service you're paying for.
Assuming you're not just paying for the ability to receive the BBC, ITV, C4 and C5 channels via satellite, that is. You can do that for free. Compare freesat with Sky's free offer at Compare Freesat and Freesat-from-Sky TV | ukfree.tv - independent free digital TV advice .
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Gareth: When the broadcasters of the multiplexes for those channels decide that it's economic to do so. They were offered the opportunity to broadcast from more sites than they did before switchover, and they turned it down on cost grounds.
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Dale: Someone's made a mistake in programming the system, probably, because those are the dates for Oxford and its relays.
I suppose it's possible that if there was a problem with the programme feed to Sudbury, that it might be taking a feed from Oxford, or at least the multiplexer that feeds Oxford. Is it happening on all channels or just the BBC?
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Whoops, I forgot about the power boost that happened on Wednesday morning. (I'm in the area, but my aerial points to Crystal Palace, not Hannington.) Mux C and D were boosted to 20 kW. This is to offset the potential for interference from Sudbury BBC A and D3&4 when they go to high power on 6 and 20 July respectively.
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Mark A: "Transmitter Engineering" just reposts what the BBC put on their 'Solve your interference problems' troubleshooter, and what Digital UK post at
Digital UK - Planned Engineering Works . The BBC put "DSO Related" on their page if they were previously advised of the 'fault', that it would be due to planned engineering works for digital switchover.
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abby gillespie: The Humax PVR 9150T is a full Freeview digital box as well as a recorder. However, it only has one tuner, so you can't necessarily watch one channel while recording another (although my 9200T allows you to watch channels that are part of the same multiplex as one being recorded).
Even if the box does not add its output so it can be tuned in as an analogue TV station - the component is called an 'RF modulator' - it usually does reproduce the input on an output socket so you can chain devices together. It should be possible to plug the RF output of one box into the input of another, you should have received a cable ('fly lead') with the box. If not you can buy a fly lead.
Alternatively you can buy a splitter to split the signal from one outlet to multiple boxes. This often produces slightly better results.
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ALL: Note that transmitters are officially off-air from midnight to (at least) 6am. You may find some services go off and on before the advertised completion time, but it is not guaranteed to be complete until then.
At Sudbury, the Multiplex A service moves to Multiplex 1's old frequency (C49) *tonight*, rather than in two weeks.
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Sudbury will be OFF-AIR from shortly after midnight until 6am (officially). Services may come and go during this time. It's recommended that you retune after 6am when all work should be complete. See Digital UK - Relay transmitter switching times for progress reports.
While maximum digital power is lower than maximum analogue power, the reduction is much less than at other sites, and the increase from pre-switchover power levels is substantial. If you had reliable digital reception before switchover started, and you have problems afterward, you could have too much signal. Remove any boosters or amplifiers, and if that doesn't help, add an attenuator.
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Felixstowe will be OFF-AIR from midnight. It is expected to be up-and-running again by mid-morning (the advice to installers says 9am). Ensure that the transmitter is fully running again before tuning in your digital box.
You can find progress reports at Digital UK - Relay transmitter switching times .
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Ipswich Stoke will be OFF-AIR from midnight. It is expected to be up-and-running again by mid-morning (the advice to installers says 7am). Ensure that the transmitter is fully running again before tuning in your digital box.
You can find progress reports at Digital UK - Relay transmitter switching times .
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Somersham will be OFF-AIR from midnight. It is expected to be up-and-running again by mid-morning (the advice to installers says 6am). Ensure that the transmitter is fully running again before tuning in your digital box.
You can find progress reports at Digital UK - Relay transmitter switching times .
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Wivenhoe Park will be OFF-AIR from midnight. It is expected to be up-and-running again by mid-afternoon (the advice to installers says 12 noon). Ensure that the transmitter is fully running again before tuning in your digital box.
You can find progress reports at Digital UK - Relay transmitter switching times .
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Woodbridge will be OFF-AIR from midnight. It is expected to be up-and-running again by mid-afternoon (the advice to installers says 12 noon). Ensure that the transmitter is fully running again before tuning in your digital box.
You can find progress reports at Digital UK - Relay transmitter switching times .
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Brian: If the old aerial works, I wouldn't replace it. Going by Justin Smith's aerial tests at Gain (curves), Again , a small log periodic (shown there as 'DM Log') should have more gain in Group A, for the PSB multiplexes, but will have less above C48, where the commercial multiplexes live.
The log periodic is supposedly more resilient to impulse interference, though, so if you find your reception breaks up when cars go past, it may help.
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Steve: DO NOT USE WOLFBANE. It is inaccurate, signal strengths shown are far lower than calculated by the ITU-R line-of-sight equation for known line-of-sight paths. I use Field Strength Calculator which shows a field strength of 81.3 dBuV/m at 66km from a 20kW transmitter on C67. Multiply the field strength shown in V/m by one million, take the base 10 logarithm ['log' on most calculators, not 'ln'] then multiply by 20.
We need a full postcode to see whether there is anything preventing line-of-sight. The Digital UK postcode checker considers how signals travel over the terrain and has factors for buildings and trees.
Bob Archer: If channels on higher frequencies break up when it rains, it often indicates that water is getting into the cables. Check that the seals on any outdoor boxes (such as a masthead amplifier or splitter) are intact and not letting water penetrate. Some aerials have a connection box on the aerial itself, where the cable connects to the aerial, again this needs to be watertight. If the cable has been up for a long time (over 10 years), the outer insulation may have perished due to ultraviolet light exposure and that again allows water to penetrate into the cable.
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Mark: Have you retuned your box since April? The 'red button' video stream, channel 301, moved from Multiplex B to Multiplex 1 a couple of months ago.
(I realise it's too late for today's game but that should sort you out for the next round.).
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G GUY: See Astra 1H/1KR/1L/1M/2C at 19.2°E - LyngSat for frequencies and channels. You should be able to get anything marked as 'PAL'.
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Lisa: Multiplex 2 did move from C30 to C33 on 20 April, because it would have clashed with high-power signals from The Wrekin. The prediction for that multiplex is poor.
Digital UK's postcode checker shows that Sutton Coldfield will be a better option for you, both now and after switchover.
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George: Only the BBC A multiplex (replacing Mux 1) and Multiplex A have moved so far. Mux 2 is still on C68 and should still be on C56. However, C56 only transmits at 1.1 kW, nearly 20 dB quieter than the new high-power BBC multiplex, and some boxes might have trouble with that much difference in signal levels.
Some boxes just tune in the first version of the channels that they see, rather than the best quality, so check whether there's another version of ITV1 up in the 800s, or somewhere else in the guide, which would be the version at C68. I'm afraid I don't know which area C56 was intended to cover.
Multiplex A, which was on C48, has moved to C49 already. This is so Woodbridge (permanently), Burnham on Crouch and Clacton (temporarily) can use C48 for BBC A.
At your postcode, Digital UK predict no reliable coverage on Mux 2 at present. I'm not sure if this is a change as they only show today onwards.
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Steve: All free-to-watch channels | ukfree.tv - independent free digital TV advice and search for 'Food Network'.
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Dale: Yes, in this interim period between the first and second stages of switchover, BBC Four and the BBC radio stations are transmitted from both high-power BBC A and low-power Mux B. In two weeks Mux B closes down and is (logically) replaced by the HD multiplex. (The HD multiplex takes over Channel 4's frequency, and Mux B's frequency is released.)
Which version was stored at 9 depends on how your box handles multiple versions; it might be the Mux B version if it just stores the first found, or the BBC A version if it stores the best quality.
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Brian: Logik is a Dixons/Currys group brand. I'm afraid they don't seem to be making much information available. Try contacting their customer support at Customer support | Dixons | .
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Dave: The irony is that the move to DAB is intended to free up the FM band for more local stations. There is actually nothing else that can reasonably use VHF Band II - the band's entire width is only 20.5 MHz, which is about the same as ONE WiFi channel in a/b/g mode. 802.11n can be configured to use twice the width, 40 MHz.
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joe abbott: It's not clear from the manual at TV Re-tune how to do a complete reset of the box, which is often necessary at switchover. On newer equipment, 'Add Channels' does forget the old locations.
My guess would be that you now have too much signal. If you have a booster or other amplifier, try removing it. Or you may need to add an attenuator.
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John A.: My mistake, Rouncefall is indeed shown as horizontally-polarized.
The timing of the signals from both transmitters reaching your aerial is critical. Outside the designed coverage area, the signals can conflict rather than help (self-interference). Digital UK's trade predictor shows variable reception whether you point the aerial to Sudbury or to Rouncefall. It only ultimately shows 'good' reception on all multiplexes from Dover.
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Ian: The 'HD Ready' logo indicates that the TV can show an HD source from elsewhere, it does not indicate that it can tune in to UK HD broadcasts. For that, you need a 'Freeview HD'-branded set-top box or PVR.
I'm afraid BBC West is not broadcast from the Ridge Hill transmitter, or any other transmitter that you are expected to get a usable signal from.
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Lisa: You are getting BBC A from Sudbury *and* Rouncefall. That's the way it now works. The signal from both transmitters adds together and (hopefully) produces better results than from one transmitter alone.
The exact influence each transmitter has depends on exactly where you are and which way your aerial's pointing. Digital UK's predictor (trade view) shows the prediction only for aiming the aerial directly at one transmitter or the other, but signals from both transmitters, plus the interference from all other transmitters, are taken into account.
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Jim: Looking at the specifications in the manual for that device, it looks like it only has an analogue tuner, not a digital one. It *might* be possible to record the programme you're watching by selecting the SCART input, but it's not exactly clear how to do that, and you might need to check that the TV is outputting the received pictures on the SCART connection. (SCART was originally designed to send signals to an external box to decode teletext subtitles and send them back to the TV to be displayed, so it has some pins designed to carry signals from the TV to the box and some from the box to the TV.)
Otherwise you would need to add a Freeview set-top box, to decode the TV signals before sending them to the DVD recorder. Connect the Freeview box to the upper SCART socket on the recorder as shown on p14 of the manual.
If you don't have the manual, you can download a copy from http://www.liteonit.eu/en/firmware-and-other.html . Select Category: Audio/Video then Model Number: DD-A110.
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Robert M, jb38: The Hitachi HDR082 is a rebadged Vestel T825. These are known to have problems with 8K mode with a negative offset. There was a firmware update available, broadcast last year, but your box may not have received it. See Unofficial Vestel PVR Information (UK) - T825 Freeview+ for more information.
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Steve Wilson: If your aerial is pointing at Sudbury but the TV can't detect the BBC multiplex, either the TV doesn't support 8K mode or the signal is *too strong*, not too weak.
The new digital signal level for BBC A is over 14 times the previous level for Mux 1.
If you have a booster or other amplifier, remove it or turn it down. If that doesn't help, try adding an attenuator.
If you're connecting the aerial input of the TV to the RF output of the PVR, consider splitting the downlead from the aerial using a splitter, and connect each device to the downlead separately.
There is a partial list of equipment known to have problems with 8K mode at http://www.digitaluk.co.uk/2kequipment .
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Robert Turney: ITV1 analogue is still available from Sudbury for the next two weeks. After that, the power level for the D3&4 multiplex will match that for BBC A, so you should expect to get equally good results. However, Digital UK's predictor doesn't offer any prediction for Sudbury at that location.
From today, BBC A is also broadcast from the Rouncefall transmitter, which shows a good chance of reliable reception now. Rouncefall and Sudbury use the same frequencies and work together to provide coverage, there is a contribution from both transmitters. Again, in two weeks it starts broadcasting D3&4 at high power. However, Rouncefall will not provide the commercial multiplexes (mux A/SDN, C/ArqA and D/ArqB shown above).
The predictor shows a good chance of reliable reception for most multiplexes from both Crystal Palace and Dover after they complete switchover next year (April for CP, June for Dover).
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P O'Donnell: For you, Cathcart, Black Hill and Netherton Brae should all provide a good chance of reliable reception. Make sure that your box is tuned to the correct frequencies for the transmitter your aerial points to.
Cathcart and Netherton Brae transmit on vertical polarization, requiring the aerial elements to go up-and-down rather than side-to-side. If your box stores the first version it finds rather than the strongest/best quality, it may have chosen to store Netherton Brae as this uses the lowest frequencies out of all these transmitters. Cathcart is at 48° east of north, so close to north-east, while Netherton Brae is at 131°, roughly south-east.
Black Hill requires a horizontally-polarized aerial, elements running side-to-side, and it is on a bearing of 80°, a little north of due east. Only Black Hill provides the three commercial multiplexes.
For completeness, Digital UK also reckons that you could get a signal from the Glasgow West Central transmitter, but there's a poor chance of reliable reception.
If you think your box is tuning into the wrong transmissions, see Digital Region Overlap for ideas on how to fix it.
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Joe: Digital UK's postcode checker shows a good chance of reception from Black Hill, Craigkelly and Darvel. It's possible that your box has tuned into the wrong transmitter. See Digital Region Overlap for suggestions on how to fix this.
It could also be that signals from Black Hill are now too strong. If you have a booster, try removing it.
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el: Can you provide a full postcode, please, so we can see where you are and what the prediction is for that location.
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darral: You will usually get better results from a rooftop aerial than a loft aerial, and from a loft aerial than an indoor one. The height of the aerial is important, as the signals are severely reduced by adjacent buildings. The signal propogation - travel - is also affected by surrounding objects, particularly metal ones.
In addition, indoor aerials are typically too small. Aerials work best if the elements are the right size, typically about one-half of the wavelength they're trying to pick up. For mid-band channels that means about 25cm. Because they're too small, or designed more for appearance than function, they usually don't have any useful amount of gain.
If you provide a full postcode, I can check whether you might be able to get a full service from any transmitter, although the terrain of South Wales does make it difficult.
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jack: If you have suddenly lost all channels, it's most likely that a cable has become disconnected, or that the aerial has been dislodged. Check for any loose or broken cables.
If this has happened, I would expect that analogue channels have also become very snowy or unwatchable.
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pmullans: Yes, TV aerials just don't come that short. See ATV`s Choice Of Aerials for digital TV for some example dimensions. That site doesn't list 'contract'-type aerials, which might be short enough, but might not give good enough performance - it depends where you are.
I do find that aerial installers tend to overdo it, fitting aerials that are way too big. Their tendency to use wideband aerials where they are not necessary causes size inflation too, because you can use a much smaller grouped aerial for the same amount of gain, particularly in the lower frequency groups.
A grid or billboard aerial is a possibility, particularly if your region has already switched over.
You could also try splitting the output of the aerial on the main house - to which I presume there are no objections! - and distributing that to the other location. You might need a small amplifier to offset the loss through the splitter and in the additional cable. If your region has not yet switched over, I would recommend using a separate amplifier and splitter, rather than a powered splitter, so that you can remove the amplifier after switchover if it is no longer necessary.
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Mark A.: While Sudbury does transmit Channel 5 analogue, it is at one-fifth the power of the other analogue channels and from aerial panels mounted half-way down one side of the mast. It's not a good indicator of whether you're using Sudbury itself, or another transmitter.
Kim Lay: Looking at your previous posts, in June 2007, you said that your aerial pointed to the 'Kent' transmitter. I assume you meant Dover. If that's still the case, yesterday's changes shouldn't have had much effect on your reception - although some boxes might store off-beam reception from Sudbury rather than the direct beam from Dover. That might cause unexpected picture break-ups on BBC channels now, and ITV1/C4/C5 if you retune in two weeks. See Digital Region Overlap for some ideas on selecting the versions you want.
You're ultimately expected to have the best chance of reliable reception from Sudbury, and once the other PSB multiplexes power up in two weeks, it will be your best option for those channels. However, the commercial multiplexes C and D are expected to be better from Dover until November. After that, Tacolneston's switchover will cause more interference to the Dover signals and it's a toss-up between Sudbury and Dover for these services.
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Bill: Check the manual for your box to see how to access the Other Channels feature. You can find a list of free-to-air channels, and the required settings to tune them in, at Eurobird 1 & Astra 2A/2B/2D at 28.2°E - LyngSat or Astra 2A / Astra 2B / Astra 2D / Eurobird 1 (28.2°E) - All transmissions - frequencies - KingOfSat .
These are only the free-to-air channels from the satellites in the cluster at 28.2-28.5°E. There are other satellite clusters viewable from the UK, but you would need a different dish, or a dish constructed to carry more than one LNB, or a motorized dish, to watch channels from those clusters. Some freesat boxes can control switches to select a different dish or LNB, and some can control a motorized dish. Look for mentions of 'DiSEqC' in the box's manual.
"Free-to-view" has a specific meaning if you're talking about 5* and 5 USA. It means that the channel is encrypted, and requires (for UK free-to-view channels) a Sky box and viewing card to watch it. However, the box and viewing card are a one-off purchase, you don't have to keep paying a subscription to watch the channels.
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Steve Wilson: Unfortunately none the pictures of the masts I've found actually indicate which way is north! C56 is reportedly omni-directional, but low power, while C68 is reportedly restricted to the east of the transmitter.
Digital UK currently predicts no coverage from either frequency at your location. This will change in two weeks at the second stage of switch-over.
It also predicts that you should have a much better chance of reliable reception on all six multiplexes if you use Tacolneston, rather than Sudbury.
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daniel, abby gillespie: Sorry, my error, the 9150T is indeed a dual tuner. I was assuming that it was a follow-on to the PVR-8000T which my parents have, which is indeed a single tuner, and that it was inferior to my 9200T.
(The 9200T has a USB download port, separate video/audio jacks and a S/PDIF digital audio output, which the 9150T doesn't. The 9300T drops the USB port but gains an HDMI port.)
abby: In that case my advice changes, you don't need the Bush box at all, unless you want to watch something else when *two* other programmes are being recorded, and what you want to watch isn't on the same multiplex as either of the recorded programmes.
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poeter: For the next two weeks, BBC One, ITV1, C4 and C5 are still available on analogue. *So far* only the BBC channels have gone to high-power digital, the other digital channels are still on low power. The other public-service channels will go to high-power on the 20th of July.
There will be some subsequent changes on 16 November, when Multiplex D changes channel so that Tacolneston can start using it the following week, and on 27 June 2012, when the final channels for Multiplex A, C and D are available - they will reach full power on this date.
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i king, Andrew: Your aerial is directional. It is designed to amplify the signals coming from directly in front of it, and reduce pick-up of transmissions coming from the side. The width of the area it picks up from - called the acceptance angle - depends on the design of the aerial, but generally larger aerials with more elements have a narrower acceptance angle.
If you want to use the Burnham-on-Crouch transmitter, you will usually get better results by pointing the aerial directly to it.
i king: it depends on the box. Some just store the first version found, some the strongest or best quality. Newer boxes will ask which region you want to store, if signals from more than one region are detected. Digital UK predict that you should get better results from Sudbury (plus the contribution from Rouncefall on the same channels) than from Bluebell Hill, so an aerial move might be worthwhile, but you might not get all multiplexes until next June when Bluebell Hill switches over. Still, they predict that you can't get all multiplexes now.
Andrew: Your box may be one that just tunes in the first version it finds. Dover Mux 1 is on a lower frequency (C45) than Sudbury Mux 1 was until yesterday (C49, now C44). Burnham-on-Crouch has started up at 100W and will eventually go up to 500W next June - you would also need to retune as it's currently using temporary channels.
Digital does not carry 'teletext' as such. The teletext button on your TV remote won't do anything. Press the red button on the set-top box remote to access BBC digital text, or the dedicated subtitles button to get subtitles.
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sue: You should do a full reset (also called default setting, first-time installation, 'virgin mode', full retune) on switchover days. This ensures it doesn't know about any channels before you start.
If you have ITV1 at both number 3 and in the 800s, you're probably getting signals from more than one transmitter. There are a few transmitter sites that carry the ITV/C4 multiplex on more than one frequency. If possible, find out which transmitter you're using and other nearby transmitters, and compare the UHF channel numbers carrying each version, to make sure that the box has tuned in the best quality version at 3. Some boxes just store the first version found, the one on the lowest UHF channel number/frequency, rather than the best quality. If this is the case you will have to either use the channel edit feature to move the one you want to position 3, or manually tune in. See Digital Region Overlap for more ideas.
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M Rose, M Adania: If you're using digital already, then you aren't using the High Wycombe transmitter. At present, this only transmits analogue signals: BBC One, BBC Two, ITV1 and Channel 4.
There has been engineering work for digital switchover this week, which I would expect to affect all channels, not just BBC One and Two. 'Transmitter Engineering' is just an automated piece of software that scrapes the Digital UK engineering page and the BBC problem reports page. The BBC only publish the status of their channels, not ITV1 and C4.
If you're using the High Wycombe transmitter, and BBC channels are back on but ITV1 is not, try the contact details at Broadcaster complaints details | ukfree.tv - independent free digital TV advice .
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Lorna Smith: Sometimes there could be a UHF channel clash between a main transmitter and a relay, or between two main transmitters, where there wasn't one before. The planners have tried to avoid it but sometimes it hasn't been possible to cram everything in, while releasing one-third of the available channels and minimizing the number of people who have to change their aerials to get the public-service channels.
People who are *only* covered by a relay transmitter that did not transmit Freeview before switchover will only get the three public-service multiplexes after switchover. I haven't seen the leaflets, so I'm not sure exactly what they say.
Looking at your previous posts, you gave the postcode BD20 8TT, which is expected to get very reliable reception. Indeed the prediction is so high that you may have too much signal after switchover. If you find that your reception is unreliable, remove any boosters or other amplifiers, and if that still doesn't fix it, add an attenuator to reduce the levels.
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m Sim: Most likely, your aerial is pointing to the Oxford transmitter. There have been no planned engineering works. We can also see reported faults on the BBC channels, which shows a problem on BBC One analogue for half an hour on Friday night, but we don't have that information for ITV.
It's possible that if you have retuned in the last couple of months, that the fringe reception from Sandy Heath - which is on a lower frequency - is strong enough for your box to detect, and that it is a model that stores the first version found in the scan rather than the strongest/best quality signal.
If so, the solution is to delete the channels you're having a problem with, and do a manual tune on C68 for ITV1/C4/C5 etc, and C54 for CBeebies. See Digital Region Overlap for other ideas.
If that doesn't resolve the issue, it could be a cabling issue. The multiplex carrying ITV1 etc is right at the top of the frequency range, and there is more loss in cables at higher frequencies than lower ones. Particularly if it's wet, water can penetrate into junction boxes and into old, perished cables, which means they perform worse: again, higher frequencies are affected worse than lower ones. This is likely to be the problem if the analogue channels have become more snowy than before.
If this is the case, you probably need to have the cables replaced. At the very least, the seals on any junction boxes or outdoor amplifiers or splitters need to be checked or replaced to stop water getting in, but there's a good chance that the cable's dielectric - the plastic or foam material between the inner metal conductor and the outer metal screen - are saturated.
Do also check that the aerial is intact and still pointing in the right direction.
The power increases greatly at switchover, at the end of September. This might make things better for a while but a cable fault will typically get worse over time.
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Ian Young: All we can say is that the commercial multiplexes have no plans to extend services to any more transmitters. They were asked, in the planning stages, and they turned it down, saying it was too expensive.
Digital UK's trade predictor reckons that you could get a signal from Black Hill with the right aerial, but the reliability is expected to be poor. You might manage reliable service with a larger-than-usual aerial. However, the cost of installation might mean it's better to investigate satellite.
Dave is a subscription channel on satellite, so you'd have to pay Sky at least £19.50 per month. Virgin Media cable is not available in your area.
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KMJ,Derby: It appears that the Sudbury transmission on C49 was restricted to the west to protect Oxford C5, and that this may have been done by transmitting out-of-phase signals from the lower aerial panels on the west side of the 'digital' mast in addition to the main signals from the top of that mast.
There was no restriction on Mux A before switchover, so it's possible that the out-of-phase signals providing the restriction are no longer transmitted - if that's how it was done.
Information sources: Sudbury Transmitter (note MUX3 = Mux A in this table), U.K. Television Stations (UHF Digital System) for aerial heights which indicate that there was a contribution from both arrays for Mux 1 and B, and the pictures at mb21 - The Transmission Gallery .
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Mark: The three public-service multiplexes - which carry the BBC channels, the primary ITV and Channel 4 channels, Channel 5, and the HD channels - will broadcast at 100 kW from 14 August (BBC SD channels)/28 August (other channels).
The other three, commercial, multiplexes, will ultimately transmit at 50 kW. They are restricted to 12.5 kW until 18 April 2012. This is when the Crystal Palace transmitter group completes switchover. We haven't been given reasons for the power restrictions, but you can often figure it out by looking at the maps of other transmitters using the same frequencies. My guess is that this is to protect viewers of the High Wycombe transmitter, although this will continue to use these channels after switchover. Some of Hannington's north-western relays (Lambourn, Chisbury, Hemdean) also use these channels, and are moving to different channels at switchover. However, Hannington's switchover is in February.
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Ian: If you're north or north-west of the transmitter, or if your aerial points in that direction, you may be affected by occasional interference from ArqB from Winter Hill, which uses the same channel (C55). Winter Hill's power level on this multiplex is restricted to reduce the problems, but some people are still affected.
Try rescanning during the day, if you last rescanned at night, or vice versa. Signal propogation - how it travels - varies depending on weather conditions and on temperature layers in the atmosphere, so some variation is normal and to be expected.
The problem will go away at switchover, as Mux D/ArqB will be moving to a new frequency that will not clash with Winter Hill.
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james cobby: The centre frequency of C21 is 474 MHz, and each channel is 8 MHz apart. To convert a UHF channel number to a centre frequency:
f = 8 x (n - 21) + 474 MHz
where n is the channel.
Check your box's manual for where it displays the UHF channel for the service you're watching. It isn't necessarily in the tuning menu.
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Steve P: DVB-T is not designed for mobile reception. The receiver has to read the entire multiplex all the time, every bit transmitted, while for DAB (and DVB-H) it knows when the data for the station you're listening to will arrive, so it can power the receiver up just for the data it needs. The Doppler effect - frequencies shift if the receiver is moving - is also a problem, as inter-carrier interference occurs. This happens at speeds well below 60 mph for the mode of DVB-T used in the UK after switchover. The Doppler effect still affects DAB, but not as much, both because it transmits at lower frequencies and because it uses fewer carriers. It's the difference between being able to use it on a high-speed train (coverage permitting) and only at walking pace.
http://www.broadcastpaper….pdf
Only the BBC National Radio stations and a few commercial radio stations are broadcast on DVB-T. The commercial stations are carried on commercial multiplexes, which have significantly lower population coverage than the PSBs, due to not being carried on all transmitters, and also at lower power than the PSB muxes on many of the transmitters they are carried on. The commercial muxes are not regionalized, so you get 'national' variants of Capital FM and Heart rather than the local breakfast show.
DVB-T is not a replacement for radio broadcasting in whatever form.
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Souriau: We have absolutely no idea. Ofcom haven't published that information yet. The RTE multiplex is not yet licensed. The digital switchover plan does not show any frequencies allocated to this multiplex and that would be where we would expect to find the information.
It looks like it will be broadcast using DVB-T2 in 16QAM 1/2 mode, and therefore you will need a Freeview HD receiver, even if the stations transmit in SD to begin with. They will probably use MPEG-4 AVC/H.264 as that's what's used in the Republic.
The latest we have is at Digital Television - Technical guidance on the availability of TG4 in Northern Ireland after digital switchover .
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David Maxwell:
Tacolneston Transmitter group works on 13 and 14 July 2011
Engineering transmitter work will take place between 00:01hrs and 06:00hrs.
TV services that will be disrupted:
Analogue services - BBC1, BBC2 and ITV.
Digital services - Not affected.
from
Digital UK - Planned Engineering Works .
It's likely that they're performing high-power digital tests - BBC Two will be replaced by BBC B, ITV1 by D3&4, and BBC One by BBC A at switchover, while Channel 4's frequency will be released, so it doesn't need to be turned off for the test. The commercial multiplexes will get new frequencies, not replacing any existing services.
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Rich: Welcome to the misery of rebadged equipment bought from an electrical retailer and then re-sold second hand or refurbished. The Bush brand is now owned and operated by Argos, who offer no support. The TU320DTR is a rebadged Vestel T845 - Unofficial Vestel PVR Information (UK) - T845 Top Up TV .
Luckily a reputable brand - Sharp - rebadged the same box as TU-TV322H, and you can find the manual at http://www.sharp.co.uk/cps/rde/xbcr/documents/documents/Marketing/Operational_manuals/pdf_OM-digitaltvreceiver-tutv322h-en.pdf .
Some boxes don't clear the saved channels before doing a scan. I'd first try the Reset procedure on page 33 of that manual, under Scenario 2.
It may be that the box has a problem with the Split NIT - a Network Information Table that is too large to fit into one Transport Stream packet - which started being transmitted from late 2008. Putting the channels in the 800s is a known symptom on some boxes, though I admit I don't see yours or any other T845 on Digital UK's list at http://www.digitaluk.co.uk/splitnit . It's worth checking whether the update listed at Unofficial Vestel PVR Information (UK) - T845 Top Up TV has been applied - if it was ever broadcast for the Bush boxes, it may be a long time before it comes around again. You'd need a classic serial cable and a PC with a classic serial port to perform a manual upgrade.
Honestly, I'd return it and get a Humax PVR-9150T or 9300T, which is a far better box and actually has ongoing support from the manufacturer.
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Roland Johnson: That all depends on the commercial multiplex operators extending their services to more transmitters. They turned down the option to do so at switchover, saying it would cost too much. These operators are focused on profit rather than public service.
I've heard rumours that they may extend to another 8 or 9 sites, but these are likely to be high-power sites that would add significantly to the overall covered area, particularly if populated with a wealthy demographic.
If you provide a full postcode, we can check the likelihood of getting a reliable service from Ridge Hill, or another main transmitter.
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Robert Sprigge: It does not appear in Ofcom's Radio Transmitter Tech Parameters document Ofcom | Tech Parameters which was last updated on the 28th of June. It also does not yet appear on the BBC's list at BBC - Help receiving TV and radio - Transmitters which goes up to 5 July.
The BBC's contribution to Ofcom's DAB coverage consultation Ofcom | An approach to DAB coverage planning does show Epping Green as a site expected to launch by the end of 2011, so it won't be long.
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roy: It's likely that you're using the Balgownie relay transmitter. If so, your aerial's rods will be going up-and-down rather than side-to-side, and pointing somewhere between north and north-east. The Balgownie transmitter is a 'Freeview Lite' transmitter, only providing the three public service multiplexes, shown as PSB1/BBCA, PSB2/D3&4 and PSB3/BBCB above. We do not know if the commercial multiplexes will ever extend their services to more transmitters - they turned down the opportunity at switchover, saying it would be too expensive.
If you have the aerial replaced, you may be able to get a reliable service on at least some of the commercial multiplexes direct from Durris. The chances of reliable reception, with a standard installation, are shown as good for Arqiva B, but variable for SDN and Arqiva A. In this area, the problem is co-channel interference from Knock More, so a more directional aerial is probably helpful.
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Jerome, jb38: Channel 5 has advertising regions as well. Only Region 2, London, is free-to-air - the other regions are encrypted. Your Sky box will use whatever version corresponds to the postcode that the last-used viewing card was sent to.
Spot Advertising Macro Map | Channel 5 shows the regions, Astra 2A / Astra 2B / Astra 2D / Eurobird 1 (28.2°E) - All transmissions - frequencies - KingOfSat shows the parameters for manually tuning the free-to-air 'region 2' transmission. Currently on 10773 H, SR 22000, FEC 5/6.
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dan: Because the commercial multiplex operators don't want to spend the money on transmitting from all sites, and they aren't being forced to do so by the regulator.
Digital UK's postcode checker (trade view) shows a pretty high (over 90%) probability of reliable reception from the main transmitter at Caradon Hill. Druid's Hill is in the way of direct line of sight to the transmitter, but there should still be enough signal refracted over the terrain. You would probably need a new aerial to use Caradon Hill.
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Mary Tudor: There is engineering work today, which means that the transmitter is off-air. There may be other engineering shut-downs during the week.
The Nailsworth transmitter relays the signal from Stroud, which relays the signal from Mendip. Engineering work is also shown at Stroud, which may explain the shut-down at Nailsworth. No work is shown at Mendip.
You can keep track of engineering works by checking
Digital UK - Planned Engineering Works .
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Peter Gordge: The adult channels share slots with other channels - the adult channels are off-air when the other channels are on-air and vice versa.
You can find a list of the slots for each channel, put together by 'Ray Cathode' at Digital Spy's forums, at http://www.bsa.talktalk.net/dtt/LCN%20&%20Multiplex%20Listings/England/Pre-switchover/England%20pre-switchover%20multiplexes.pdf . The black boxes show the 'slot' shared by each channel.
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Alan Matthews: Despite the title of this article, switchover is not really complete.
The commercial muxes remain on relatively low power until after Dover's switchover next June. They have all changed to their final mode, which requires more signal-to-noise ratio than the mode they used before today. The transmissions have doubled in power, but the required S/N ratio is slightly more than this, so effectively coverage has been reduced.
The new mode is somewhat more prone to interference as well - which is why the broadcasters stopped using it in 2002.
Digital UK predicts that you won't get a usable signal on Arqiva B (which carries ITV4 and Yesterday) until April next year. It may work once it moves to C63 on 16 November - you will need to retune.
In earlier switchovers, the commercial muxes have remained in their pre-switchover mode if they could not adopt high power or their final channels. However, the increased capacity has already been sold, to BT Vision for Sky Sports 1 and 2, so the mode changes are being done before power increases enough to compensate.
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MikeH: Have you done a full retune? Use the 'First Time Installation' option in the General menu to do this.
It's possible that the overall signal strength is now too high and overloading some part of your equipment. If you have a booster, try removing it, or turning it down if it's variable. If that doesn't help, try adding an attenuator.
As a relatively new box, the Sharp *should* ask which region you want to store, if it finds more than one, and it should store the best quality signals. However, some boxes do just store the first version found, which may not be the best version. Looking at the manual, I can't see any way to check which UHF channel it's actually tuned to for a particular service. You may need to do a First-Time Installation with the aerial unplugged to reset to a completely blank state, then use the manual tune features to select the versions you actually want.
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carl: Did you have the BBC channels after the first stage of switchover? If not, your box may not be able to handle 8K mode. See whether it's on the list at http://www.digitaluk.co.uk/2kequipment . That's a list of known-bad equipment, there may be others that also don't work (or sometimes boxes are rebadged, the whole family of equipment doesn't work, but only one appears on the list).
If you hadn't retuned since mid-2008, you might also now be experiencing the 'Split NIT' problem for the first time. See http://www.digitaluk.co.uk/splitnit for equipment known to have a problem with this.
No changes have been made to Freesat, you should check the connection to the dish. That would point to a problem with the cabling, generally. Are you using a communal system, sharing an aerial and dish with your neighbours? If so, the communal system may need adjusting - check whether this is currently being done.
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jb38, Keith Hook: The Sudbury transmitter transmits the Anglia region, and the probability of reliable reception is VERY HIGH - not 'not possible'. I assume you're referring to the probabilities for Sandy Heath, also part of the Anglia region.
Keith, are you missing any other channels or just those on Mux 2/D3&4?
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SJ: 'Blurring' can be a sign that the receiver is on the verge of being unable to correct all the errors in the signal. Since it's just started happening, my guess is that this is due to too much signal, which is causing distortion. If you have a booster, you should remove it now, or turn it down if you lose channels when you remove it. If not, consider adding an attenuator.
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Alan Matthews: When all is complete, on 27 June 2012 (the date of Dover's second switchover step), the power increases will be:
SDN by 5.5 dB (3.57x) to 50kW
ArqA by 12.2 dB (16.7x) to 50kW
ArqB by 13.6 dB (22.7x) to 50kW
These are all substantially greater increases than they have already had.
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Briantist: No, it is not for the London 1 and London 2 multiplexes, unless Arqiva have supplied the wrong map. The website Ash linked to is specifically for the London 3 multiplex, which is licensed to a different operator from the other two (each is a different operator).
The linked map does appear to be the correct map, because it shows the Brookmans Park transmitter near Potters Bar. Neither London 1 nor London 2 use this transmitter.
I think you need to go back and figure out why your maps don't correspond to Arqiva's published coverage maps.
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John Fisher:
Signal *strength* is the raw level of power coming in on the selected UHF channel, from *all* sources - the transmitter you want, other transmitters using the channel, signal distortion and noise.
Signal *quality* is a measure of how much interference or distortion there is. Any of either causes the box to read the wrong value for the carrier. The signal is encoded in a way that allows the box to determine the most likely value, but this decision can be wrong if the levels of interference, noise, or distortion are too high. To combat this, the signal carries redundant information to help guide the decision and correct the errors (called 'forward error correction', FEC). Signal quality is usually an indicator of how many errors were corrected.
Unfortunately on most boxes, both measures are useless for diagnostics. The 'strength' is usually a percentage relative to the maximum possible input from one multiplex alone with no interference, but as this differs from box to box, 50% (say) on one box may mean something different from 50% on another box. As a general rule you should stay well below 100%, as the combined power from all multiplexes (and remaining analogue channels) from all receivable transmitters would exceed the power on that one single test multiplex. The upper limit recommended by the Confederation of Aerial Installers for one multiplex (before switchover), which allows for a combination of five high-power analogue and six low-power digital signals, falls at about 50% on my box (Humax PVR-9200T). Some boxes apparently under-read if the signals are actually over the maximum they can handle.
Signal quality on many boxes (again, including mine) is simply 100% minus the relative number of uncorrectable errors over the last few seconds. It doesn't tell you how many errors were corrected, which means you can't find out how close to the point of break-up you are, and you can tell visually and audibly if it isn't capable of correcting all the errors, as it usually starts breaking up or giving audible 'pop' sounds at this point.
If the number of uncorrectable errors is low, you can get a more blocky or blurry picture without actual tearing (where a whole line is discarded). This is right at the top of the so-called 'cliff edge'. Otherwise, if the signal quality is good enough - sufficient signal, low enough noise and interference - all errors can be corrected and the decoding is perfect. Digital can tolerate up to about 20dB, or 100 times, more interference/noise than would start to cause problems on analogue, though the problems would be very minor at this point. However, you could still get an understandable picture and sound on analogue with noise levels greater than will cause complete failure on digital.
Note that you can still get a blocky or blurry picture with perfect reception, if the broadcaster is compressing the picture too much. We can only cram nine channels into the space that used to carry one by throwing a lot of information away. It's designed to throw away the least-noticeable information, and only transmit the changes between pictures, but if too much information is discarded you can see the joins between coding blocks, distinct colours where it should be smooth, or blurry detail that should be sharp. There's nothing at all you can do about this - the information was never transmitted, it wasn't lost in transit.
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Ed: The analogue television service was planned carefully to allow four complete networks to be transmitted from every site in the country. (There are a very few one- or two-channel fill-in relays where a region has later been split, to allow an area to get its 'correct' local news.) The original digital signals were crammed into this plan, at whatever level would cause minimum interference to analogue services, and from very few sites: the 'main' transmitters (fed directly from studios) and a few relay sites that served a large chunk of the population, or parts that the advertisers considered important. There simply wasn't room for any more power increases.
The frequency plan wasn't just for this country, but also to allow for the transmissions from Ireland, France, the Netherlands and Belgium (being most affected by our transmissions).
There were various changes over the years since digital services started in 1998, particularly the equalization programme of 2000, bringing the coverage of each multiplex from a particular site to a similar level (originally the plans might have huge coverage on Mux 1 but very low coverage on Mux D), the mode change of late 2002 (effectively increasing coverage with no power increase, on the four multiplexes that changed mode), and power doubling of many multiplexes at many sites in 2003/4. These changes could be made as interference wasn't as bad as first thought, or few people were actually using theoretical coverage from one transmitter: some changes were required to analogue relays to prevent people from losing reception. There were diminishing returns on these changes, though, and analogue switch-off is really the only way to improve it further.
The switchover is to turn off the analogue signals, so that the digital signals (at least for the public-service broadcasters) can take over their frequencies and, largely, power levels. But it can't happen until analogue is switched off, because it will cause too much interference at other sites.
You get two weeks to sort out problems - BBC Two is switched off first, replaced by high-power digital BBC services. Then, two weeks later, the other four analogue channels are switched off and the remaining high-power digital services start. If you had digital before, you need to retune on both days, as the signals move to the much better frequencies vacated by the analogue transmissions.
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Ben: Crystal Palace has NOT yet switched over. That happens next April. The Sudbury transmitter, which serves parts of Suffolk and Essex, has just switched - but some of the multiplexes are still on quite low power, because their new frequency allocations are still in use at Dover and/or Bluebell Hill, so they have had to stay on pre-switchover channels.
Digital UK's predictor does think that you'll get best reception of the PSB multiplexes - those run by the traditional analogue broadcasters, carrying their main channels - from Sudbury. The commercial multiplexes are expected to be problematic from there at the moment even with a roof-top aerial. This should improve as they move to clearer channels - you should retune on 27 June next year. The Arqiva B multiplex will move to UHF C63 on 16 November this year, but this change is not expected to improve your reception.
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Jane Hore: Can you provide a full postcode please, so we can see the prediction for you?
Using Bing Maps to get a co-ordinate for Oulton Broad, I got a nearby postcode of NR33 8QH from nearby.org.uk. This shows very high probability of reliable reception, suggesting a problem with your system rather than any issue at the transmitter. Is analogue reception clear? If not, is it snowy or is there 'herringbone' patterning? If snowy or lacking colour, I'd suspect a broken aerial or cable - if herringboning, it could be too much signal and you should remove or turn down any boosters or amplifiers.
In answer to your final question, the transmitters are owned and operated by Arqiva. This is the successor company to NTL, which took over the IBA's transmitters in 1993; in 2007 Arqiva bought up the company that eventually ended up owning the BBC's transmitters after they were privatized. Tacolneston was originally a BBC transmitter, the IBA (for ITV and later C4) used the site as a tenant for colour TV. At other sites, e.g. Sandy Heath, the IBA was landlord and the BBC the tenant.
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Barny Otoole: It's actually quite a tricky problem, because the island of Ireland uses a different grid reference system to that of Great Britain and the minor British Isles. It's based on a projection from a different point - a different way of displaying the curved surface of the Earth on a flat piece of paper. The maps are then displayed by Google Maps, which requires points in GPS co-ordinates, based on a third different projection and even a different model of the Earth's shape.
I suspect the part of Brian's software that gives the distance treats IJ163867 (which nearby.org.uk gives as the Irish Grid containing the centre of your postcode) as square IJ of the Ordnance Survey GB National Grid, which is actually just off the west coast of Norway. This would produce an error of 1,063km from the south-west corner of OSGB square NW to the south-west corner of 'IJ'. It should instead say I = Irish and use the OSNI transformation to GPS co-ordinates.
Digital UK's predictor - which I hope is based on the correct information, since it displays the OSNI logo - shows that you are 16km (10 miles) from Divis.
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Dave, Briantist: C40 will now be retained for TV broadcasting, along with C39, replacing C61 and C62 which are to be released for 4G. This change happened after most of the plans were made, so they're being redone.
Because the retained channels are in a different aerial group from those being released, they're actually moving allocations of C61 to C49 and C62 to C50 (in general, though it depends on interference). To make this possible, some sites allocated C50 move to C40 and C49 to C39, if they would interfere. It does depend on the aerial groups for the transmitters as well.
It's possible that Patcham's allocations may change before switchover to accommodate changes at other sites, or that C40 gets used by one of the main transmitters, preventing its use here.
Other local TV services are likely to only be available from the main transmitter sites. Certainly the tentative plans published as part of Ofcom's consultation several years ago - based on unfinished plans for the main multiplexes - only included main sites.
For the postcode you provided previously, it looks like Whitehawk Hill would be a reasonable option after switchover, though Patcham is the best option.
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jane hore: That doesn't usually happen on analogue. Are you sure you checked the right thing?
It's rare for that to happen on digital as well, it normally goes blocky for a period first. If you're using a separate Freeview box from the TV, try pressing the MENU button on the Freeview box's remote. If the menu doesn't appear, the problem is the connection from the Freeview box to the TV. Replace the SCART cable. If it still happens, try a different SCART socket at either end, because there may be a broken connection.
If the menu does appear, check to see whether the problem occurs when the heating thermostat switches on and off, or a heating pump is running. These can cause a lot of electrical interference, which is picked up by the TV aerial cable. Newer cables, termed 'satellite-grade', with better screening will usually pick up less interference, but getting the thermostat or pump sorted out is a better solution.
Do also make sure your mobile phone is well away from TV aerial cables, as its transmissions can also be picked up and cause problems.
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Mr R B Boyd: Looking at Digital UK's 'Almanac' document, feeding this transmitter is a bit tricky. At switchover, the feed changed from being directly off-air from Ilfracombe to being picked up via Combe Martin (itself fed from Ilfracombe). Ilfracombe was originally fed from Caradon Hill and moved to Huntshaw Cross.
If there's a problem anywhere in the chain from Huntshaw Cross - Ilfracombe - Combe Martin - Berrynarbor, it'll affect your reception.
Digital UK's Planned Engineering Works page does list 'Service Shutdowns' this week on Ilfracombe and Combe Martin - they must have forgotten to update the status for Berrynarbor (and Chambercombe, which is also fed from Ilfracombe).
Looking at the Combe Martin page, it looks like the problem was upstream, as the same issues are reported at the same times.
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jordan: Digital UK's aerial trade predictor shows a good chance of reliable reception from The Wrekin/Lark Stoke/Bromsgrove (already switched, but COM muxes on low power/busy channels) and from Brierley Hill. These predictions are based on a rooftop aerial, but The Wrekin is shown as 100% across the board after the COM muxes move to full power on 28 September (when Sutton Coldfield switches over). The PSB muxes are showing at 100% now.
Boosters generally do nothing useful. Try it without. They're only of any use if the receiver is particularly noisy (which Freeview boxes shouldn't be) or if the signal levels are so low that the box can't detect them reliably, but the interference is still very low.
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James Clifford: Can you get the BBC and ITV channels at all? Did you have digital TV before switchover?
If you had digital before switchover, and you can't get BBC channels or ITV, *and* you had poor analogue reception before switchover, there's a possibility that you actually had the wrong group aerial for Sudbury. It could have been a group C/D. This particularly might be the case if best analogue signals came from a relay, and the aerial was moved around to point to Sudbury for digital. You need a group E or wideband aerial (which cover groups B and C/D) for all services from Sudbury.
If you had clear analogue reception before switchover, you may now have too much signal, causing the signal to be distorted and undecodable. If you have a booster or amplifier, try removing it or turning it down. If you don't have one, or that doesn't help, try adding an attenuator.
If you do have the channels listed above under PSB1/BBC A and PSB2/D3&4, it's likely that your aerial is a Group B (which was all that was needed for analogue reception). A change to a Group E or wideband is likely to be necessary for reliable reception of the commercial multiplexes, both at their current temporary location and their final homes.
I would have expected you to have most trouble with ArqB, which carries Yesterday and Film4, because it's on the lowest power level. That may well point to it being a problem with too much signal.
We need a full postcode to see what the prediction for your location is. A postcode area covers hundreds of homes and usually a few miles, so isn't precise enough. UHF reception can vary greatly over distances of only a few metres.
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Dr. R. D. Feltham: The biggest lie that Digital UK have been propogating is that it will be two stages and done. That isn't true for quite a lot of areas, where there is a clash of allocated channels with those used by another region that is yet to switch over. In these cases there can be many later stages of power increases and sometimes mode changes and channel changes. At Sudbury, there's a channel change in November to get out of the way of Tacolneston's switchover, and final channels and power levels can only be adopted once Dover has switched over next June.
However, power *has* been increased on all six multiplexes already, albeit - for three multiplexes *not* carrying any historical analogue channels - not yet to the final designed level. This power increase is the *source* of problems for a number of people whose aerial system was upgraded for digital, as often those systems have too much gain, causing distortion. That distortion was barely noticeable on analogue, for digital it can prevent the system decoding.
It doesn't help that the strength meters on many boxes mis-report the level if the multiplex can't be decoded, and give the impression that they can handle far higher inputs than they actually can. (On my box, the DTG-recommended lower and upper limits falls at 17% and 58%.) The boxes frequently don't store the best/strongest version, either, sometimes storing signals from further away, again giving the impression that there has been a reduction when in fact it's that a distant transmitter has had a large increase, and your box is now incorrectly storing that rather than the transmissions from the mast your aerial is pointing at.
Again, in some cases, a nearby signal is too distorted after the power increase, preventing a box that does store the best signal from using what should have been the best, causing it to store a weaker distant transmission, which would appear to be a reduction in signal strength.
Please also be aware that signal propogation varies over time, with changes in weather conditions. The scale of this variation can be 100 times or more, and it can vary by frequency, giving different levels of variation on different multiplexes. The small power increases for the muxes yet to reach full power are smaller than this scale of variation, so on some days received levels could be lower than before switchover, despite the actual increase in transmission power. (On the worst days, even the PSB muxes could have a received level lower than the best days for the pre-switchover Mux 1 and 2.)
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Chris: Yes, confusingly, Digital UK report a status of 'working normally' for analogue on transmitters that have switched over, in their reports of planned engineering work. Analogue is off, and it's staying off.
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Briantist: UKTV also gets some subscription revenue. All their channels are subscriber-only on satellite, they are not available on Freesat or Freesat-from-Sky.
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David: North Norfolk is primarily served by both the Belmont and Tacolneston main transmitters. There are a number of relay transmitters - relaying Tacolneston - in the area which provide a full four-channel analogue service now and will provide a Freeview Light service after switchover.
There are also some two-channel relays which broadcast BBC One East and ITV1 Anglia only, in areas that are currently better served by Belmont. At switchover these will also become full Freeview Light transmitters.
In addition there are new relays at Great Yarmouth and Lowestoft, which will start up when Tacolneston switches over in November. Also, some relays in this region are getting the same power as before switchover - usually there is a reduction, as less power is required for digital - and some have a large power increase.
Please check the Digital UK postcode checker for an indication of what you can expect - though there are still some low-lying coastal areas where the signal will be blocked by the terrain.
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Mark: The relay in the Sandringham estate is called 'Kings Lynn' by the broadcasters. It currently only transmits BBC One Anglia and ITV1 Anglia - the signals from Belmont in its coverage area for all four main analogue channels are strong enough, but BBC One and ITV1 are the wrong region (since Belmont was re-attributed from Anglia to Yorkshire in the 1970s).
You should get digital equipment now and retune tomorrow, and on the 17th, to keep receiving BBC Two and Channel 4. You will still get BBC One East and ITV1 Anglia from Kings Lynn on analogue - you'll need to retune again on 9 November (for BBC) and 23 November (for ITV1) to get the new digital signals from Kings Lynn.
Digital UK's predictor suggests that you should get a full service from Belmont.
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Steve Williams: That's why "ends" is in quote marks. Yes, the commercial multiplexes are often delayed as they have to have new frequencies allocated, which are often in use elsewhere.
Sudbury can't start using the channels ultimately allocated, because they're in use at Dover (BBC Two analogue and two low-power multiplexes). Dover BBC Two would cause a lot of interference to the multiplex using this frequency, and Sudbury high-power services would damage the two low-power ones at Dover, so you have to wait until after Dover switches over next June.
In the case of the change in November, Sudbury ArqB is currently using a frequency that will be needed by Tacolneston from 23 November, and so it takes over the one freed by Tacolneston on 9 November.
The problem mostly doesn't arise for the PSB multiplexes as they are generally taking over three of the four analogue frequencies, which are usually clear of interference for a large enough distance, because of the original analogue plans and the way that low-power digital was fitted around that.
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s hugh-jones: I suggest you do a full retune.
It's possible that changes have been made to the Packet Identifiers (PIDs) which tell the box which bits of the transmitted data-stream contain the sound and teletext data. The video and audio, and subtitles, are carried in separate datastreams, so the first stage of decoding has to know which one contains what information for which service.
Boxes are supposed to check the Program Map Table every time, so they pick up the associations properly even if the broadcasters have changed something. Yours may not be doing this and may be expecting to find the audio and teletext data at an old location. As I said, retuning should fix this problem.
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Richard: You can probably get a list of major holdings via Companies House as I believe they are required to report. Go to WebCHeck - Select and Access Company Information and search for British Sky Broadcasting.
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Steve Williams: I assume they wanted to reduce the volume of support calls! The UK is unusual in that there is still such a high proportion of terrestrial viewing, most other countries which cut-over in a short period have far fewer terrestrial viewers.
I think it's down to a combination of the strength of the BBC, the fact that all channels could be received from the same transmitter using the same aerial, a blanket television transmission network covering a very large part of the population, and the early provision of a Digital Terrestrial Television system (even if the pay-part collapsed, at least it did so quickly). Cable systems weren't allowed to carry other channels until 1984, when the relay transmitter network was mostly complete. For these reasons, cable never had the take-up in the UK that it has done overseas.
At the start of 2006, which is roughly when the phased rollout plan was committed to, 53.8% of viewing on primary sets was terrestrial (analogue or digital), while it was 77.7% on secondary sets. That's a heck of a lot of phone calls if it went wrong!
The largest individual switchover is expected to be that of Crystal Palace and its relays, potentially serving over 4.5m households. The biggest before that will be September's Sutton Coldfield/Emley Moor. By themselves, they serve 1.87m (SC) and 1.55m (EM), but both have a lot of relays. Winter Hill (2.69m) serves more households but it was done separately from any other.
The phased rollout has also allowed Arqiva to save a bit of money, by having a smaller stock of temporary equipment that can move from site to site as installations are upgraded, rather than having to upgrade everything at the same time.
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Michael: Can you tell us which channels you have, and which you don't have?
My guess is that you've got everything on BBC A and D3&4, and nothing from SDN, ArqA and ArqB multiplexes. I also guess that you don't have HD equipment, so nothing from BBC B.
Looking at the predictor, it's probable that the low power signals on SDN, ArqA and ArqB are just too weak, relative to the amount of interference, for you to get them reliably at the moment. While these temporary locations have double the power of the services that previously used those frequencies, the new mode requires slightly more than that. (SDN hasn't actually changed mode but it has taken over Mux 1's frequency, which used the more robust - but lower capacity - mode.)
There's probably nothing you can do except wait for next June. A different box might be able to handle the difference in levels better, or a slight repositioning of the aerial might help, but you should get a professional to check this.
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david wood: Are you actually using the Belmont transmitter? Your aerial would point north-west, across The Wash, if so. Digital UK's predictor reckons this is your best bet, but you would have needed to get a wideband aerial for best results.
Please note that this transmitter starts the switchover process, to increase digital power and move to clearer frequencies, tonight. The transmitter will be subject to interruption from around midnight (probably 12:20am as that's when the programme ends, though it could be as late as 1:10am) and will continue to be disrupted until 6am. The new high-power digital service should then be running reliably, and you must retune to pick it up.
If you never changed your aerial for digital, this should be a lot more reliable as it's replacing the old analogue BBC Two service.
As Brian says, the signal levels should be more than sufficient without amplification and it could cause distortion. If you find you can't get the BBC digital service from Belmont, or it's unreliable, remove the booster (if any).
The remaining analogue services will be switched off, and replaced by high-power digital services, on the morning of the 17th. Mux C and D will remain on low power temporarily until 23 November, until after Tacolneston has switched over. You will need a wideband aerial for these services.
Note that Belmont carries BBC Look North (Yorkshire & Lincolnshire) and ITV1 Calendar (Yorkshire) rather than the Anglia regional service. There are a number of relays providing this service. Your best bet is Kings Lynn, which will switch over with Tacolneston in November. At present it only provides analogue BBC One East and ITV1 Anglia.
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Briantist: You may not get a detectable signal from Ireland or Sudbury, but you will get interference. For Ofcom's 800MHz clearance consultation, Arqiva provided a plan of how to handle it, which details potential interactions between Mendip and Rouen and Cap de la Hague, should it be allocated C48 and C51 to replace C61 and C62.
However, I suspect this is in the 1% case (e.g. ducting), not general problems with reception.
John_Ha: I'd start by checking that cables are still making good contact and that the aerial is intact. Cable insulation does deteriorate with exposure to UV light and water penetration becomes a possibility - higher frequencies are affected worse by water problems than lower ones.
Amplification can also cause a problem - digital TV requires very linear response, it can't handle any significant distortion. If you have an amplifier or booster, try removing it or turning it down. Amplifier power supplies can introduce ripple if they start to fail, and ripple in the PSU causes ripple on the output, which again causes periods of drop-out or distortion.
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Nigel, Briantist, Keith: http://www.digitaluk.co.uk/transmitternetwork/tools__and__resources/almanac/installer_newsletters_transmitter_groups2009_pdfs/Belmont_and_Olivers_Mount_1MO_FINAL_July_2011.pdf says:
"Oliver's Mount and Hunmanby will carry the same regional news services as Emley Moor."
That'll be Look North from Leeds then.
The BBC call the Hull service Yorkshire & Lincolnshire.
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James: You will need to retune to continue receiving BBC channels, but other channels should still be fine as they haven't moved.
If you're using a communal aerial, the system may need adjusting for the new channels and signal levels - contact your building manager or landlord. It's possible that this work is currently being done.
If you're using a booster, try disconnecting it, as it may now be getting overloaded and distorting the signals.
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I realise it's a lot of work, but would it be possible to incorporate the interim stages for transmitters that can't go to final channels in one step?
I know that the information is available from Postcode Checker - Trade View (for example) but I find it more accessible in your format.
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Michael: Yes, as I thought, the BBC A and D3&4 multiplexes only at present.
Digital UK have failed to properly communicate that Sudbury can't go to its full, final configuration yet, giving the impression that everything is done. The commercial multiplexes actually remain at lower power and on busy channels. There will be another retune on 16 November, to free up a channel for Tacolneston, which isn't expected to make any improvement on your reception but may help some people. The final step, with all multiplexes going to their final channels and power levels, doesn't happen until 27 June 2012, when the Dover transmitter switches over.
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Paul: First, forget about averages, they're meaningless. The coverage on one set of channels is not altered by the power level on another set of channels, and what you care about is whether it's strong enough on the channels you do want.
On digital, TV channels are carried in a 'multiplex', a digital transmission that carries lots of channels in the space that one analogue channel used to take. This is done because there's much more capacity available that one compressed TV channel takes (three to four times typical DVD rates, TV is more heavily compressed than a DVD), and there's a certain amount of space wasted if you tried to divide up the broadcast channel into smaller blocks.
All that's happened so far is that the high-power BBC A multiplex has replaced the old analogue BBC Two and the low-power Multiplex 1, which carried most of the BBC channels before yesterday. Because BBC Two's analogue channel is being freed for 4G mobile services, the digital transmission has actually taken over BBC One's frequency and BBC One has temporarily moved to BBC Two's old location.
That new BBC A multiplex is transmitting at a maximum of twice the maximum power of the former analogue transmitter on that frequency. It's 20 times the power of the old low-power Multiplex 1.
Where there are factors of millions of times between the highest and lowest levels accepted, engineers usually use a logarithmic scale - decibels. A multiplication of the original by a factor turns into an addition of the logarithms of the original value and the factor. Multiplying power by two is adding (about) 3 dB and multiplying by ten is adding 10 dB. It's a useful scale if, like human hearing and vision, there is a logarithmic response, or if, like TV transmission, the source is diffused in all directions, but we largely 'see' just the straight-line path between transmitter and receiver.
On the 17th, the remaining analogue and low-power digital transmissions will be switched off. The replacement high-power transmissions will start up at their allocated power levels - 2000W for the three multiplexes that were gifted or licensed to the public service broadcasters (BBC A, D3&4, BBC B/HD) and 1000W for the three multiplexes licensed to commercial operators (SDN, Arqiva A, Arqiva B).
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Alan Parker: It depends where you are.
Switchovers for the following regions aren't scheduled until 2012:
Meridian (excluding Oxford)
London
Tyne Tees (no dates announced)
Ulster (no dates announced)
Switchovers for some transmitters in these regions will require changes after the publicised 'switchover' dates, in 2012:
Anglia (Sandy Heath, Sudbury)
Border (Caldbeck)
Central (Oxford)
STV Central (Darvel)
West (Mendip)
West Country (Stockland Hill, Huntshaw Cross)
The interlocking nature of the frequencies used at sites around the country means that some changes have to be delayed so that as few people as possible lose any service they already had.
Where I say 'channel' below, I mean the radio frequency that the service or multiplex is transmitted on.
At almost all sites, the three public service multiplexes - carrying the BBC services, ITV1, ITV1+1, ITV2, Channel 4, C4+1, E4 (except Wales), More4, Channel 5, and the four HD services - start up on their final channel at switchover and at full power. This is because they are directly replacing the analogue channels, which don't clash with any pre-switchover services at other sites.
At some relays, the post-switchover channels are different from those used before switchover, and are not available until changes happen at other sites. Where this happens, a temporary channel is used, but at full power. In some cases, if a relay only transmitted two services - cases where the 'wrong' region was transmitted from the best main transmitter - the HD multiplex is postponed until later (e.g. Derby).
The three 'commercial' multiplexes, which carry the rest of the services, are harder. The analogue system was planned for four channels at each site, meaning at least two more frequencies have to be found for sites carrying the commercial multiplexes (only the 81 main sites that broadcast digital before switchover). Two chunks of space aren't available, either, with C31-C38 being released for some undefined future use and C61-C68 released for 4G mobiles, which often rules out at least one of the old analogue channels. They have to be co-ordinated with overseas broadcasters too. So there are often clashes between what has been allocated, and what is available at the time of switchover. Those clashes might be with a relay that will move to new channels at switchover, or with a low-power digital service elsewhere that is yet to switch.
Where this happens, the best option is usually to leave the low-power versions of the commercial multiplexes alone for the time being - on their original channels and original power levels - until the other site switches over and releases the required channel. Where possible, a (relatively) small increase in power is used, and/or a retune to use one of the frequencies used by a multiplex that has moved to its final location.
However, some services have started up in the BBC's spare capacity before switchover, and they must move to a different multiplex at switchover because this capacity is removed (for HD services). To do this requires the Mux C/ArqA and Mux D/ArqB multiplexes to change mode, and this mode needs more power. Many sites get a small power boost, but this may not be enough for all viewers to keep the services in the interim period before the final channels and/or power levels are available.
A few sites have to swap their interim channels for different temporary channels, before getting their final locations, to work around more than one clashing site.
If you provide a full postcode I can give an indication of when you will need to retune and whether any interim arrangements apply.
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Mark A.: Just like the broadcasters, we use decibels, because the signal strength reduces logarithmically with distance, not linearly.
One-fifth is actually not a very large drop in power - especially compared to the difference in signal-to-noise ratio required for PAL, which was 43 dB, and that for the post-DSO digital mode, about 20 dB. The other 16 dB is a margin to allow for the normal variation of levels - on analogue you'd see increased snow, annoying but not totally obscuring the picture, but digital would start cutting out.
Your box likely has a very wide range of gain available. Mine claims to handle 35 to 95 dBuV, a range of 60 dB or one million times the power. (1000 times the voltage, because power = voltage squared divided by resistance.)
At some sites, the pre-DSO digital power can be a tiny fraction of analogue power - e.g. Sutton Coldfield analogue is 125x more than low-power digital, or Sudbury analogue was 227x more powerful than Mux D. Using your method, the bar would be incredibly short, giving quite a false impression.
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jason: Because the channels that will eventually be used are still required at other sites. Both the allocated channels and the temporary ones clash with other sites. Moving to full power now would damage other people's reception, either of analogue or of low-power digital services.
In order of what's going to happen:
On 31 August, Mux A will move from C43 to C31, at the same power level, to free C43 for Sutton Coldfield. C31 is released by Waltham on that date.
On 14 September, ArqB moves from C67 to C48, its final frequency, at full final power level. C48 is in use at Oxford before this date. Mux C changes mode, becoming ArqA, and takes over C67 from ArqB, at the same power level.
On 23 November, ArqA moves from C67 to C52, which is currently used by Tacolneston, at full power. This is its final channel.
On 9 May 2012, Mux A changes mode, becoming SDN, and moves to C51 at full power - this is its final location.
On 27 June 2012, the vertical beam tilt - the angle of the main part of the transmission - will be raised. It is currently restricted to the south-west, to protect services at Rowridge. Effectively this will increase power levels for viewers further away from the transmitter.
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Briantist: I'd been meaning to mention that. I'm certain they will not shut down ITV1 analogue early.
There will be some clashing with Belmont C60 but that has been handled by delaying power-up - it will double to 8 kW at DSO2. Hemel Hempstead will release C60 for Oxford on 14 September; this is a PSB channel at Oxford, launching at full power (100kW). It's already an analogue frequency there, so there might be a small net reduction in interference at TAC for the last couple of months.
There's a note in the 'Supplementary License Documents for DSO' version 3 that says, for Mux 2, "until 17 August 2010 services will be provided on channel 60". If we assume that 2010 should read 2011, it does match where Mux 2 is now, and the date that Mux B moves from C58 to C66, and Mux C from C61 to C68. I have to assume that this note is just complete rubbish.
The document does not mention the Mux B and C retunes at all. It does seem to indicate a power increase to 10kW on Mux A at some point between now and DSO2, or that could just be more rubbish.
There is a version 4 document now at http://licensing.ofcom.org.uk/binaries/tv/sup_dso/digital-stations-v4.pdf which looks like it has the same notes, but for Mux 2 the rows of the spreadsheet are too short and only the first line is visible.
Ofcom are really, really failing with switchover. They're letting the broadcasters do whatever they want and not keeping up with the paperwork.
The best source of information seems to be the 'Trade Region' section of DUK's postcode checker at Postcode Checker - Trade View , though that doesn't include power levels.
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snowflake: You may be in a region where the local ITV1 service, and the Channel 5 ad region, are encrypted. The viewing card is required to decrypt it. Also, the postcode that the card was registered with is used to determine which version to store. Make sure the viewing card is still in the box and that it's making good contact.
I believe Briantist intended to link to What can I do when my Sky Digibox says 'No Signal' or 'Technical fault'? | ukfree.tv - independent free digital TV advice which goes into more detail.
If that process doesn't work, you may need to buy a new viewing card from Sky.
Alternatively you can use Other Channels to tune into any ITV1 regional variant or the unencrypted version of Channel 5. See Astra 2A / Astra 2B / Astra 2D / Eurobird 1 (28.2°E) - All transmissions - frequencies - KingOfSat or Eurobird 1 & Astra 2A/2B/2D at 28.2°E - LyngSat for the tuning details.
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Peter Henderson: We simply don't know yet. Typically the dates are announced with about a year to go. For example, London (4 April 2012) was announced on 7 April 2011, Meridian West (lead transmitter Hannington: 8 Feb 2012) on 15 Feb 2011, and Meridian East (lead Heathfield, 30 May 2012) on 10 May 2011. The later the announcement comes, the later the switchover is likely to be. I think the shortest period between announcement and switchover was for the Channel Islands, about 10 months in advance.
Every region that Ulster TV borders has already switched over, so I don't really see any reason why it can't all happen on the same day. The Sutton Coldfield/Emley Moor switchover next month affects many more relay transmitters and people than all of the Ulster region. Fenton switches on the same dates so that's three 'Full Freeview' transmitters on the same date. The most is five main transmitters with some work to do on the same day - Oxford DSO2, Mendip, Bromsgrove, Lark Stoke and The Wrekin retune and power up all on 28 September, Nottingham and Sheffield have a retune and power up scheduled for the day before.
Some co-ordination may still be required with the Republic, I'm not sure if they've started up Saorview on final channels or not. Because of the pull-out of the commercial provider, they seem to have only launched two multiplexes so far, and one of them just contains placeholder content according to Wikipedia, so they may not have as tight frequency requirements as we do, right now.
Looking at the Geneva 2006 frequency plan, it appears Ireland asked for 4 frequencies at each major site, in addition to their existing analogue frequencies, so the co-ordination may already have been done. (They still use Band III VHF for RTE1 and 2 at many sites, so only six UHF frequencies total are required at those sites, before analogue switch-off.).
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dan preston: It is likely that the 9200T stores the first version found rather than the best quality, although you'd have to ask why it wouldn't pick all services from Sandy Heath.
Your best bet is the Hemel Hempstead transmitter, which requires a vertically-polarized aerial pointing east-south-east. You might alternatively be aiming at the Crystal Palace transmitter, which is horizontally polarized, and due south-east.
If the box was just storing the channels based on the first found, you would expect it to store Crystal Palace C25 C22 C28 C32 C34 C29 (1-2-A-B-C-D) in preference to Sandy Heath C27 C24 (C21) C43 C40 C67 (C21 carries HD signals which the PVR9200T won't tune in). Hemel Hempstead is up at C48 C55 C59 C60 C62 C65.
Check which way your aerial's elements are running - up-and-down or side-to-side - and if up-and-down, try tuning into the Hemel Hempstead frequencies, otherwise, try Crystal Palace. However, the predicted reliability from Crystal Palace is variable, up until switchover.
If you are using Hemel Hempstead, be aware that you will need to retune on the 16th of September, as Mux 1 and A move to temporary frequencies to allow Oxford and Sandy Heath to use their current frequencies.
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Richard Evans: Some TVs or boxes can get confused if they're retuned from one site to another. It might be necessary to do a full reset/factory default/first-time installation on the TV.
If you get really stuck, try doing a full reset with the aerial unplugged, in order to delete all channels, then manually tune the frequencies you actually want.
Do also be aware that the Humax PVR9200T has an RF output, that is, it puts the currently-tuned picture and sound on the RF cable going to the TV, as if it was an analogue TV station. Check that this doesn't clash directly with any multiplex you want to use, isn't immediately above or below one, and that it isn't 5 or 9 channels away either.
My PVR-9200T seems to create a lot of noise on and around C36 no matter what I set the RF output channel to, when it's in standby.
The Humax also has a small amount of gain and noise, so if reception is slightly marginal, you may find that it works better or worse when the box is in standby.
There will be a retune at Bromsgrove on 28 September, which will move the COM muxes to their final channels and power levels.
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Thursday 16 June 2011 1:29AM
Green Gordon: You can find a map of Scottish Gaelic speakers at File:ScotlandGaelicSpeakers2001.gif - Wikipedia, the free encyclopedia . The highest percentages are in north and west Scotland, particularly the Western Isles.
Radio nan Gaidheal is available on FM. It is also available on the Central Scotland regional DAB ensemble, and on a number of local ensembles, but it is not on the BBC National Radio ensemble. The ensembles have to be identical on all transmitters that carry them, and BBC National Radio (12B) is carried across the entire country, from Dover to Eitshal on Lewis.
The local ensembles:
Aberdeen, run by Switchdigital Scotland (UTV). Broadcasts from Durris, Meldrum and Mormond Hill.
Ayr, run by NOW Digital (Arqiva). Broadcasts from Darvel, Brown Carrick Hill and West Kilbride.
Perth & Dundee, run by Score Digital (Bauer). Broadcasts from Angus, Purin Hill, Kirkton Mailer, Faire Mhor, and possibly Kinross.
Inverness, run by Score Digital (Bauer). Broadcasts from Mount Eagle.
You can get an idea of the Freeview coverage from the *main* transmitters at mb21 - Transmitter Information - Analogue Television Map , though this is really an analogue TV map. It doesn't show the coverage of the relays, which - in the difficult terrain of north-west Scotland - are numerous.