All posts by Mike Dimmick
Below are all of Mike Dimmick's postings, with the most recent are at the bottom of the page.
Heavenscentrose, Dazultra: You are both likely to be using the Whitehawk Hill transmitter, which is off-air for engineering works today and yesterday. Check
Digital UK - Planned Engineering Works for updates.
| link to this comment |
Canukinuk: Check whether it's a model that uses GuidePlus rather than the standard Freeview EPG. If you're having trouble getting Multiplex A - the information is attached to the bid.tv channel - this may explain the problem.
You might see if it's possible to put the TV in 'standard Freeview' mode.
Otherwise, if you're experiencing break-up on the BBC channels and the other affected channels, but not on other channels, it could be too much signal (see above). However, all multiplexes carry regular Freeview EPG data for all other multiplexes, though the services on the same multiplex are prioritised.
Some equipment gets confused if there are multiple copies of the same channels. Ensure you do a full retune/full reset/first-time installation/default setting/'virgin mode'/reinstall all channels, to clear out everything it previously thought it knew. If you still have duplicates after that, see Digital Region Overlap.
| link to this comment |
stafford: If you have ITV4 but not Film 4, check whether Film 4 appears in the 800s. If it does, you probably have a box that can't handle the larger Network Information Table, or otherwise has a problem with the NIT.
Check http://www.digitaluk.co.u…tnit , a list of some boxes known to have a problem with it.
Otherwise, check with the box supplier.
| link to this comment |
k: For FreeVIEW you need to use an aerial connection, which is a push-in connector. This might be connected to your Sky box at the moment, to distribute to other rooms in the house.
For FreeSAT - free TV through a satellite dish - the connection from the dish uses a screw-on connector. Just transfer this from the Sky box to the Freesat box. However, you need a second, completely independent, connection from the box to the dish if you want to guarantee recording two programmes at the same time. You cannot split an existing cable. The recorder sends some signals back up the cable to the LNB (the box at the end of the dish arm) to tell it what range of channels to select, and each tuner has to be able to select any of the four options.
Some installers do use screw-on connectors for aerial connections as well, but the last cable to the TV or box will end in a push-in connector.
| link to this comment |
Claire Evren: For satellite TV, you need a cable running from the dish to the box. This is the screw-on connection typically labelled LNB1 on a satellite receiver. If you only have an aerial lead, which pushes in (typically labelled RF1), you would need to get a cable run from the dish to your bedroom.
You can connect to the TV with EITHER HDMI or SCART, you don't need both (and this will often result in getting SD pictures on HD channels). If the TV has HDMI, use that.
| link to this comment |
Ryan: You should be getting 100% signal *quality*. You will not get 100% level and you don't want it anyway - see Freeview signals: too much of a good thing is bad for you | ukfree.tv - independent free digital TV advice .
| link to this comment |
Iain: See Freeview reception has changed? | ukfree.tv - independent free digital TV advice .
| link to this comment |
Ryan: That assumes you have a box where the signal quality is calculated as percentage of data received without errors, after all error correction. Most boxes do. Unfortunately that makes it a completely useless stat, because it cannot tell you how far away from break-up it is. It will only go below 100% when it's already starting to break up!
| link to this comment |
brian walker: Please provide a full postcode. Note that many relays are still off-air as they had to wait for work at the main mast to be complete, the last is actually not scheduled to complete until 4pm as it relies on four intermediate hops.
| link to this comment |
bill whyte: See Digital Region Overlap. My guess is that your main TV simply stores the first version it finds, not the best quality or strongest: the Belmont transmissions are on the lowest frequencies.
| link to this comment |
Jon-G: The list of relays and times is at Digital UK - Relay transmitter switching times . Some will be off-air until 3pm.
Since relays simply retransmit what they receive off-air from the parent station (which for some relays is another relay), you can't put up a caption specifically for the viewers of that relay. Also, most people don't know which relay they're using! (They usually don't even know which main transmitter provides the service.) Most relays only serve small pockets that aren't covered by a larger transmitter. It's very hard to target communications specifically to viewers who will have a long outage, so you just get generic messages of 'could be off 'til lunchtime'.
| link to this comment |
Steve P: Nottingham is part of Waltham's group and would display East Midlands.
Dave Jenks: The work was being done this morning in daytime, expected to finish at 12 noon, rather than in the early hours. It could be that services were off-air when you retuned.
Do check Digital Region Overlap, to see if anything there applies to you.
Digital UK predicts a variable service from the Nottingham relay for you, you're expected to get a much better service from Waltham or Sutton Coldfield. If the aerial points south-west, and is oriented with the elements going side-to-side, the box *should* tune to Sutton Coldfield as that's what the aerial is pointing at. If it points slightly south of east, that's Waltham. If oriented vertically - elements going up-and-down - and pointing roughly due north, it's aimed at the Nottingham relay.
| link to this comment |
Jack Johnson: There will be no need whatever to do that after switchover, and there is no prospect of any changes being made before switchover.
There are no free channels in this area - Fawley Channel 5 had to close to allow Rowridge to take over C37 - and the 2K mode doesn't lend itself to Single Frequency Network operation.
You should replace the aerial entirely. They are not designed to work with elements missing and are not designed to have parts replaced, either.
| link to this comment |
John Ormerod: HD services start from Rowridge at the second stage of switchover, 21 March 2012. I don't know where the November date has come from, perhaps you are close enough to a West or Westcountry transmitter that the Freeview HD site (which scrapes the Digital UK predictor results) thinks you can get it from there - though this would be November 2009 or November 2010. The only transmitter site switching over *this* November is Tacolneston near Norwich.
The line-up for regions that have switched over is currently:
BBC One HD
BBC HD
ITV1 HD
Channel 4 HD (4hd)
BBC One HD, ITV1 HD and 4hd are all simulcasts - they broadcast exactly the same as the SD version of the channel. If the programme was made in HD, the HD version is broadcast, otherwise the SD programme is 'upscaled' to 1080 lines. The exception is that BBC regional news is not yet carried on BBC One HD - when this is on, BBC One HD broadcasts a caption telling you to switch to BBC One.
BBC HD always broadcasts HD content. This might be a simulcast of something on BBC Two, BBC Three or BBC Four, or it might be another programme made originally for one of those channels in HD.
It is expected that by the time Rowridge switches over, a fifth HD channel will have been squeezed in, but the decision process of what it will be has only just started.
| link to this comment |
Nicholas: The + or - indicate that the centre frequency of the transmission is +167 kHz or -167 kHz from where it would normally be. There's enough margin either side that it stays within the 8 MHz bandwidth.
As to why they do it - before switchover, it was to keep the transmission further away from an analogue signal that could interfere.
After switchover, offsets are used to keep those transmissions further away from neighbouring frequency bands. C21 usually gets a + to keep it away from anything below (e.g. emergency services TETRA radio).
Originally, C62 was going to be the top channel, but C61 and C62 are now going to be released so C60 becomes the top channel and gets a - offset. C31-C40 were going to be released too, so C30 gets a - and C41 a +. However, C39 and C40 are now retained (in place of C61 and C62), so C39, the new band edge, gets a + where it's used.
If one channel has to have the offset at a transmitter, an adjacent channel might also have one, to keep the inter-channel spacings. In extreme cases, all channels get an offset. For example, at Caldbeck, where 9 channels are required for all multiplexes as it carries Scottish and English versions, the lowest channel is C21 and gets a +, which causes C22 to need a + offset, which causes C23 to need one, and so on.
Low-power relays are generally allowed to have more emissions out-of-channel anyway, so typically don't have offsets.
| link to this comment |
John Dusconi: My guess is that you were away when Sutton Coldfield switched over. You need to do a full retune of your box. Look for a full retune, default setting, full reset, first-time installation, 'virgin mode' or 'reinstall all channels' option.
If the manual doesn't make it clear how to do this, try looking at TV Re-tune .
| link to this comment |
Mr B: The messages cannot be customized for each relay transmitter. The whole point of the relays is that they just retransmit what they receive from the parent transmitter. If the message said '6am' that would be wrong for some of the relays. So it's left a little vague.
If the message listed all of the times for all relays, it wouldn't be any more helpful as viewers generally don't know which relay they're using.
| link to this comment |
Aynsley: You might get a weak analogue signal from Hannington, which doesn't switch over until February.
Some DVB-T2 equipment measures T2 signal strengths differently from DVB-T. It's not clear whether you're measuring values from the same card or from multiple cards.
The HD mux from Oxford does indeed use BBC One's old channel, C57. Analogue had to be switched off to allow high-power digital to use the old analogue channel allocations. It was a good plan in the 1960s and so it forms the basis for the post-DSO plan too - it means that nearly everyone should be able to get the PSB multiplexes with no changes to their aerials or communal systems, even those which only distribute specific frequencies.
| link to this comment |
Chris.SE: The move to C67 was a very late-breaking change, the Digital UK Installers Newsletter describing today's retune was issued on the 29th of August showing the move to C56 (with no offset), then reissued a day later showing the move to C67.
The trade view when plugging in a postcode does show the correct information, but the 'trade region' page doesn't.
Ofcom's most recent licensing document http://licensing.ofcom.or….pdf also shows C67 from 28/9/11 to 28/3/12.
| link to this comment |
Dave Jenks: Do you have the latest firmware? It was broadcast over-the-air on 4 July 2011; if you don't have it you can get it from
Welcome to HUMAX [UK]
. The version numbers are also listed at that page.
Freeview HD equipment *should* prompt you for the region to select when tuning for the first time. If this box doesn't, check with Humax support. You might be able to get it to prompt again if you select Factory Default from the Installation menu, rather than Automatic Search.
| link to this comment |
Mal: Is that an *actual* channel scan or is it being downloaded from some website? The necessary information is all carried in the Network Information Table on all multiplexes, in the terrestrial_delivery_system_descriptor. However, a lot of PC software doesn't actually read the descriptors and instead downloads the information from a website.
The exception is that PSB3's descriptor is a t2_delivery_system_descriptor instead - because it is carried on DVB-T2, not DVB-T. This confuses several boxes.
COM5 is actually on C67, 842 MHz, but it was advertised that it would be on C56, 754 MHz.
To convert from a channel number to a frequency: Subtract 21, multiply by 8, add 474.
If the transmitted descriptors are wrong, you could try telling the BBC - go to BBC - Help receiving TV and radio , enter your postcode in the upper right under 'Diagnose your problem' and follow through the wizard. The people really responsible are DMOL DMOL | Home Page but they don't have any customer services facilities.
| link to this comment |
Jack Sukerman: I'd look for any other equipment, such as a Sky box, that has an RF output on C66, C67 or C68. You will need to retune that to a different channel - perhaps down at C21. If you're not using the feature to distribute the box's output to other TVs, turn it off entirely if possible. Or, simply don't pass the aerial signal through the box.
If you don't have anything like that, check that the cables are waterproofed and that the cable run is as short as possible - losses along cables are greater at higher frequencies. Water in cables increases the losses further and again higher frequencies are affected more than lower ones. If cables can rub against bricks or tiles, the insulation may be letting water in directly; if not, check that all connection points outside (including the aerial) are sealed, and any covers are on the bottom side so that any water that does get in can drain out.
| link to this comment |
Alex B: Bit of disagreement on Mux A/SDN's current mode. DUK's installer newsletter says it should have changed to 8K mode, the postcode checker still shows it in 2K mode.
The installer newsletter shows FULL power - 100kW - for SDN, and Ofcom show no restriction after today.
Ofcom's licensing information shows ArqA at 26 kW and ArqB at 25.7 kW until 28 March 2012, which DUK's installer newsletter say is to avoid interfering with Salisbury.
(References to these documents are in my earlier post.).
| link to this comment |
David: There is no mention of DVB-T2 and only the Freeview logo is shown, not Freeview HD. I'm sorry, it looks like it isn't compatible. You would need an additional Freeview HD box, but it's unlikely you'd be able to record from it.
I'd get in touch with them, see if you can return it.
| link to this comment |
jordan: Mux 7 and 8 are several years away and still might not actually be licensed for digital TV, although that's looking more likely.
| link to this comment |
k w wild: The Wrekin is no longer transmitting on C53 or C57. It moved to final channels this morning.
Chances are you actually have too *much* signal. Anything you do to correct this may well stop the West Midlands services working, though.
For best results from Cefn Mawr you need a SMALL aerial oriented vertically - elements going up-and-down - pointing roughly south-south-east (158°). For best results from Sutton Coldfield you need a horizontally-polarized aerial pointing east-south-east (116°). For The Wrekin, a horizontally-polarized aerial pointing directly south-east (133°) would give the best results.
Using grouped aerials, you would use a C/D for Cefn Mawr, a Group B for Sutton Coldfield, and a Group K or wideband for The Wrekin.
You may find that switching to horizontal polarization and aiming the aerial somewhere between Cefn Mawr and The Wrekin gives best results; signals from Cefn Mawr should be stronger without significant aerial gain than from The Wrekin. If not, you may have to consider combining two aerials, one vertical, one horizontal.
| link to this comment |
Pedro B, Brian G: Have they *ever* worked? If so, go to BBC - Help receiving TV and radio , enter your postcode under 'Diagnose your problem' and follow the wizard. If you keep saying 'no' to 'Does this answer your question?' you eventually get to a web form where you can report it.
If they have never worked, please see What does "Full HD Ready" actually mean? | ukfree.tv - independent free digital TV advice to check whether you have compatible equipment.
| link to this comment |
k w wild: This site is not always entirely up-to-date. The Wrekin, Bromsgrove and Lark Stoke all had a change yesterday to get the commercial multiplexes onto their final allocations of C41, C44 and C47. These channels were previously used by low-power multiplexes at Sutton Coldfield; after Sutton Coldfield's DSO last week, The Wrekin/Bromsgrove/Lark Stoke could all move to the final channels.
Digital UK's installer newsletter describing the changes at The Wrekin can be found at http://www.digitaluk.co.u….pdf . Posts on The Wrekin transmitter page on this site confirm that the changes did happen.
If it works on an indoor aerial, the problem is too much signal from the main aerial. The relative amount of interference should be the same on the indoor aerial as on the rooftop aerial (may be slightly different as the two will have different amounts of cross-polar rejection). If you have an amplifier (sometimes called a booster), remove it. If not, or if that doesn't help, add an attenuator.
| link to this comment |
Steve P: The Wrekin no longer transmits on C24 or C31. SDN moved to C41 yesterday morning. Mux A stopped using C24 at switchover, taking over C31 from Mux 2.
| link to this comment |
Tony: If it's a shared aerial, get in touch with your landlord or agent. See PARAS - Professional Aerial Riggers Against The Sharks for some more ideas of who to talk to.
The system may need recalibrating or retuning, depending on what sort of system it is. D3&4 should have been OK, though, as it uses BBC One's old channel - I would have expected problems on the commercial multiplexes (SDN, ArqA and ArqB) as they use channels that have never previously been used at Sutton Coldfield.
If you have a Sky box, or something else with an RF output, check that the RF output isn't anywhere near any of the multiplexes. You might get this problem if it was on C37, I suppose, because signals at N+1, N+5 and N+9 are typically affected, though I would expect BBC A to have problems as well. I'd look at putting an RF output somewhere in the C21-C30 range or up at C52-C60.
| link to this comment |
Tony Scull: The 'no problems' message comes from scraping the BBC's reception website, and this is only done periodically. By clicking through the 'BBC Reception Test' link, I can see there actually was a problem reported from 13:08 to 13:13 today.
To report a problem, go to BBC - Reception problems , select 'No' under 'Does this answer your question' and click Continue. If you keep following through the wizard, eventually you get to a form where you can enter a problem report.
If you still have problems that don't match up with the BBC website, it's possible that you have too much signal. See Freeview signals: too much of a good thing is bad for you | ukfree.tv - independent free digital TV advice .
| link to this comment |
David Cusworth: Transmitter Engineering is an automated poster that scrapes the BBC Reception and Digital UK Planned Engineering Works pages. Because the wording of these pages can change frequently, older information is de-emphasised. This was to ensure posts from actual humans could be picked out - particularly necessary at sites like Emley Moor where the engineering work went on and on seemingly without end.
In this most recent case, the information is actually the same for the last three posts, but the BBC site reports 'today', then 'yesterday', then gives the actual date. Because the text has changed, the automated process posts a new message, even though the *meaning* of the text hasn't changed.
| link to this comment |
Anthony R Lea: You're getting confused between ITV1, ITV2, ITV3 and ITV4, which have different content, and the time-shifted version of those channels, with a '+1' after the channel name. These simply broadcast the same as the main channel, but an hour later, in case you have missed it.
It's a very cheap way to sell more advertising space, or charge more for the same ad space.
In the early days, you might get a message saying that the programme cannot be rebroadcast. That meant the channel didn't pay for the rights to broadcast it again, or the rights to time-shift a live football match.
Also, ITV haven't paid for enough equipment to time-shift all regional content, so you may find that ITV1 +1 has a different news service from ITV1. This is the case both on Freeview and on satellite and cable.
Generally ITV1 is the general entertainment channel, ITV2 is more youth-oriented, ITV3 runs archive content from ITV licencees and occasionally from the BBC, and ITV4 is sports-oriented. Freeview only carries the time-shifted +1 versions of ITV1 and ITV2; ITV3 +1 and ITV4 +1 are available on satellite and cable.
| link to this comment |
Judith Lee: Two multiplexes at Mendip moved to their final channels on 28 September, and these final locations clash with the transmissions from Usk.
My guess is that your aerial is horizontally-polarized and pointing at Mendip. Digital UK predict that you should get a reliable service from Usk if you have the right aerial set up correctly.
You will not be able to get the commercial multiplexes from Mendip any more, however.
See Will there ever be more services on the Freeview Light transmitters? | ukfree.tv - independent free digital TV advice for the explanation of why Usk will not get any more services.
| link to this comment |
Rod Roberts: *Just* Sky News or are other channels from ArqA missing? If other channels are missing, did you have a problem receiving Film4, ITV4 etc before Wednesday's retune?
If so, you have a problem receiving C67. This could be down to a Sky box or other device with an RF output on C66, C67 or C68. You should set the output to somewhere in the C21 to C30 range.
Another reason is just that higher frequencies carry less well along cables than lower frequencies. I see you're splitting your aerial feed - if you're splitting at the back of the TV, you will probably get better results from splitting as close to the aerial as possible. If you're distributing the output of a Sky box, this is obviously not possible.
ArqA will move to its final channel on 28 March 2012. We don't know yet what it will be, but it will be lower than C60.
| link to this comment |
Peter Smith: The reason for transposing on analogue is to avoid ghosting - due to the processing delays in the amplifier, the direct path from the transmitter can be shorter than the path via the cables. If field strengths are high enough, the direct path shows up as a ghost image.
Digital TV is designed to cope with delayed paths - indeed multiple paths are used deliberately in some areas, called a Single Frequency Network - and you should be fine without transposing.
Property managers should look at the appropriate section of the Digital UK website, at Property Managers - Home .
The transmissions *do* include descriptions of where to find other multiplexes belonging to the same transmitter or group, but very few boxes actually pay any attention to that information. (We wish they did, it would save all this retuning hassle!)
| link to this comment |
kevin standbridge: If your aerial points to Crystal Palace - which it probably does if your switchover date is April 2012 - the problem is probably that Sandy Heath SDN multiplex also uses C31, the same as the pre-switchover HD transmissions from Crystal Palace. It moved to this channel on 31 August. The exact behaviour will depend on how your aerial handles signals from other directions, and the relative propogation of both transmissions (which changes with the weather and with the time of day).
In my opinion, the planners have made a mistake by moving Sandy Heath SDN to C31. It had to move away from the pre-DSO allocation of C43 as that was needed at Sutton Coldfield, but cannot yet take C51 (the final allocation) as that's still needed elsewhere; it had to go somewhere, but I don't think this was a good choice.
| link to this comment |
Brian G: At the link that Briantist provided, the BBC's Reception Problems page. If you're having a problem that isn't shown there, say 'No' to 'Does this answer your question?', click Continue, then keep going through the wizard until you get to the problem report form.
The BBC use a mixture of direct off-air monitoring, reports from a small group of viewers, and reports from the general public. The direct off-air monitoring is typically only at major transmitters.
| link to this comment |
Briantist: Update on current power levels - according to Ofcom "Table of Digital Terrestrial Broadcasting Stations for Multiplex Licences" v5:
SDN: C48, 100kW
ArqA: C67, 26kW
ArqB: C52, 25.7kW
| link to this comment |
Stuart O.: The voltages we're talking about are very low. The recommended signal level for analogue was 60 to 80 dBuV - which is 1 millivolt to 10 millivolts. The normal level for the signal on a cable from another piece of equipment, such as SCART, is 1 volt peak-to-peak, 50 to 500 times the size of the signal arriving at the TV.
The problem is that most boosters are simply one transistor, as is the mixer circuit in the tuner. (The mixer downconverts from the frequency arriving on the aerial to a much lower intermediate frequency; it does this by controlling the gain of an amplifier with a local oscillator circuit, that outputs a pure tone at the tuned frequency.) Digital TV requires that any amplification is linear. A transistor's transfer curve is actually exponential - Bipolar Transistor - Characteristic Curves , second diagram down - but if you use a small enough region of it, it's approximately enough linear. If the input is too large, the range of the curve covered becomes larger and it's no longer linear.
For analogue transmissions this didn't actually matter too much - it was noticeable if you knew what to look for, but the transmissions were spaced far enough apart that it didn't really matter. For digital it causes problems both within one multiplex and for adjacent multiplexes - it's a problem called intermodulation.
At extreme high levels it can cause clipping as the amplified signal reaches the upper supply voltage - the maximum that the transistor can switch - or the ground voltage - no current flowing at all. Neither of these cause damage either, and you would notice intermodulation long before clipping was a problem.
| link to this comment |
Rod Roberts: The overall signal levels have been increased this week as well as the changes to channels. I suppose it's possible that you could have too much signal, although I would have expected that to affect the more powerful multiplexes, not the weakest. See Freeview signals: too much of a good thing is bad for you | ukfree.tv - independent free digital TV advice
| link to this comment |
Mick Lemon: Correcting Briantist: Waltham is HORIZONTAL, Nottingham is VERTICAL. Nearly all main transmitters use horizontal polarization, nearly all relays use VP.
| link to this comment |
John Daly: Since you don't mention problems on Pick TV (LCN 11) or Yesterday (LCN 12), which also require a wideband aerial, I'm going to guess that you have some device interfering with C41. If you have a Sky box from which you distribute channels around your home, you will need to retune it. See Single Frequency Interference for more information.
Signal levels are also generally increased, it's possible you could now have too much signal. See Freeview signals: too much of a good thing is bad for you | ukfree.tv - independent free digital TV advice .
| link to this comment |
Simon: See Single Frequency Interference - it could be that there is some other device blocking that channel.
This is also the only channel adjacent to another channel, and is the weaker of the pair. It could be a problem of too much signal. See Freeview signals: too much of a good thing is bad for you | ukfree.tv - independent free digital TV advice .
| link to this comment |
Andrew McPartland: There's a manual for this box at TV Re-tune productmanuals (or at least STBHDIS2010 which I assume is very similar). Have you tried using the Factory Reset feature, to see if that will allow you to select a different transmitter?
You should always select whichever transmitter the aerial is pointing to, not the nearest to you, as the aerial is directional - it is designed to reject signals from other directions. (This is not perfect rejection, some signal from other directions is still picked up.) Crystal Palace is slightly east of due south, while Sandy Heath is slightly west of due north.
For best results when feeding multiple rooms, you should split the cable as close to the aerial as possible. Try to avoid using amplification if you can; if you can't, add just enough to offset the loss in the splitter.
Digital UK do predict that the chance of reliable reception from Crystal Palace is poorer on Multiplex 2 than on the other multiplexes, at present. A long cable run will make this more difficult. It's expected to be better after switchover.
If using Crystal Palace you will need to retune on 4 and 18 April 2012, for switchover; if using Sandy Heath there are retunes on 23 November 2011 and 9 May 2012. On both occasions it's recommended that you do a factory reset.
| link to this comment |
Paddy: At that postcode it looks like the problem is that Sutton Coldfield now (since 21 September) uses C42 and C45, and those transmissions are powerful enough to knock out LYM.
You're not really in the planned service area for this transmitter, the radiation pattern shows a -7 dB (80%) reduction in your direction.
The alternative Welsh relay listed by Brian's predictor, Llanfyllin, uses the same channels as Fenton's commercial multiplexes, so again, Digital UK offer no prediction for either Llanfyllin or for Fenton's commercial multiplexes.
The mast owners are Arqiva, but you can only blame the planners and the regulator for this. The easiest option may be Freesat. It's certainly possible to build antenna arrays that are more directional than a single antenna, and to get more directional/higher-gain aerials, but honestly, a satellite installation is cheaper.
If there is a large population that's affected, you could talk to Ofcom about a self-help relay: Ofcom | Self-help TV Relays and Digital Switchover
| link to this comment |
Steve E: Over the last few days, the weather conditions have been right for signals to travel a lot further than normal. That's probably the most likely explanation.
Rowridge Mux 1 and 2 are now co-channel with Crystal Palace Mux A and Mux C; a digital channel - even at lower power - does more damage to another digital channel than an analogue channel does. Or, given your aerial points roughly due south, it could be interference from France.
At switchover, Rowridge will be much more powerful so this should not happen as often; if it still does, you could consider changing the aerial to vertical polarization - all services will transmit on VP from 18 April 2012, and the commercial multiplexes will be more powerful on VP than on horizontal polarization.
| link to this comment |
John: If you had reliable reception before switchover, chances are you now have too much signal. See Freeview signals: too much of a good thing is bad for you | ukfree.tv - independent free digital TV advice .
| link to this comment |
Phil: It may be co-incidental, the hot weather is helping distant signals arrive much more strongly.
In Windsor I would expect you to be using the Crystal Palace transmitter, but I can't be sure without a full postcode.
| link to this comment |
Mark Heselden: The boundaries between this site's predicted 'best' area for one transmitter and another are fairly arbitrary and probably wrong - like most of the predictions, because far too much of the information is kept private by the broadcasters/transmitter owner.
In this case, it's because the coverage area is divided - by the tool that generated the map - between Crystal Palace and Croydon. Croydon only normally transmits Channel 5, although in a dire emergency it can transmit the main four analogue channels (Crystal Palace's own reserve antenna and transmitters would have to fail first). So this line is completely erroneous.
There's an analogue coverage area map dating from the 1980s at mb21 - Transmitter Information - Crystal Palace - this was measured, rather than predicted. Post-DSO digital TV coverage should be substantially similar.
| link to this comment |
Simon: I'd look for another device with an RF output - perhaps one tuned to C36. See Single Frequency Interference for the types of device that might be doing this.
Even the box's own output might be causing it - my Humax PVR-9200T's RF output defaults to C36, despite the high likelihood of clashing with analogue Channel 5 at a large number of sites (well, before switchover started anyway).
| link to this comment |
Lou: If there is an aerial socket, it's likely that there is a communal aerial system already. Contact your landlord or agent to see whether they have made provisions for digital TV already, and how they will handle switchover. If *analogue* TV doesn't work, definitely get in touch - check with other residents to see if it's a common fault.
See also PARAS - Professional Aerial Riggers Against The Sharks for general advice for tenants.
| link to this comment |
J N Collis: Firstly, make sure you do a full retune from scratch. The option might be called full reset, First Time Installation, Default Setting, 'Virgin Mode', Factory Reset, or something similar depending on the box or TV. You may find instructions at TV Re-tune . Newer equipment (since 2009) should have included a leaflet specifically telling you how to retune at switchover - do the same now.
If that still doesn't help, and it's only the channels on the SDN multiplex that are affected (see the Lark Stoke transmitter page), look for any piece of equipment with an RF output, such as a Sky box or an old VCR, or even the Freeview box itself, and make sure that is set to a channel well away from any multiplex. Above C50 is probably sensible. The RF output can cause problems on the tuned channel, on adjacent channels, and on channels 5 and 9 higher than the selected channel.
Lark Stoke never carried analogue Channel 5, so even very old equipment could still be set to output on C36, which is very likely to cause problems with C41.
| link to this comment |
RobWhitwell: Does anything else on the SDN multiplex work? For example, ITV3, Quest, Pick TV? If they do work properly, switch to ESPN, then press MENU and go to Status, Signal Detection. If that says it's using channel 31, then it's probably an issue with the CAM or the viewing card. Try turning off the PVR using the switch at the back, unplugging the CAM and removing the viewing card, turning on the PVR, turning it off again, and plug the CAM and viewing card back in.
If it's not shown as using UHF channel 31, try pressing MENU, then going to Installation, then Default Setting, to wipe all channels and retune from scratch. If, after that, it doesn't show as C31, do the Default Setting again but this time don't save the results of the automatic tune. Use Manual Search to scan C24, C27, C31, C48 and C67.
The reason for this is that the PVR-9200T appears to just store the first version of the channels that it finds, rather than the strongest or best quality. In the recent weather conditions, signals from Crystal Palace - which uses lower channel numbers - could be stronger than usual.
It's also worth checking that the PVR-9200T's RF output is well away from the desired frequency range. I'd put it around C55. The setting for this is in Preferences, UHF Output. The Default Setting option resets this to C36. This shouldn't clash with anything that you're using, but it can't hurt to keep it further away.
If signals from CP *are* travelling further than usual, it could simply be a clash with the Crystal Palace 'temporary' HD service, which also uses UHF channel 31. In this case it may come and go with changes in the weather. The problem will ultimately be resolved when Crystal Palace finishes switchover on 18 April next year (and therefore stops using C31).
| link to this comment |
Christopher: If that's her postcode then yes, it is expected to give good results.
An aerial upgrade should not have been necessary if analogue signals were clear. It could have resulted in too much signal. Or, it could mean that signals from Divis are picked up strongly enough to be stored in preference to those from Limavady. It may be worth checking whether another version is present somewhere else in the programme guide that works better. If so, a manual retune should sort it out - see Digital Region Overlap for other suggestions.
| link to this comment |
Steve P, RobWhitwell: C67 is definitely in use, it carries Multiplex C until after Tacolneston's DSO. It will move to its final channel, C52 (becoming ArqA), on 23 November.
| link to this comment |
Frances et al: it's *probably* an error at Sky's broadcast centre or Arqiva's multiplexing centre. The mention of a delay and 'press red' suggests that it might be a bug or incompatibility in new MHEG software for the Sky Text service.
You could try doing a factory reset on your box. This might also be called a full retune, first-time installation, 'reinstall all channels', default setting, or 'virgin mode'. If you've needed to do a manual retune in the past, you will need to follow whatever steps you did then.
Richard and John: If you did a full retune/factory reset at the last round of changes at your transmitters, I'd be very surprised if the box had managed to screw up its programme guide this soon. That would point to a general fault in transmission.
| link to this comment |
jb38: C59 is the only one of the lower-power multiplexes adjacent to another mux. Even at its current lower-than-final output it is more than twice the power of pre-switchover Multiplex C, and should have similar noise characteristics: though the relays at Lambourn, Chisbury, Hemdean and High Wycombe are closer than the nearest relays that previously used C51, Chisbury and High Wycombe will continue to use C59 after DSO, so I have to assume they aren't a major problem. ArqA does need a bit more than double power compared to Mux C, due to the mode change, but it should be roughly equivalent in coverage.
Given all that, I suspect people having problems with C59 are quite likely to have too much signal - see Freeview signals: too much of a good thing is bad for you | ukfree.tv - independent free digital TV advice for more information.
Otherwise I'd be looking for a device with an RF output on C50, C54, C58 or C59 which could be generating local interference. I would expect other multiplexes to suffer as well, though, at least with some of those frequencies. See Single Frequency Interference for the sort of thing to look for, and don't rule out your Freeview box itself, it may have an RF output particularly if it's an older model.
| link to this comment |
Tim, Suzanne, Simon, Ron Valentine: Having looked at the Digital UK predictor's results, which show 99-100% probabilities across the board, the problem is very likely indeed to be too much signal.
| link to this comment |
Brian: You presumably have a box that stores the first version of the channels that it finds. Due to the hot weather, the signals from distant transmitters have been coming through a lot more strongly and were - presumably - strong enough to be detected.
See Digital Region Overlap for tips on resolving this problem, although it may well go away if you retune once this spell has passed. For now, you may find the correct service somewhere else in the channel list, e.g. around 800.
| link to this comment |
Son in Law: The SDN multiplex, which carries ITV3, is at full power since last week's retune.
The prediction at SP8 4AD is much better than that at SP8 5PY, so I would expect something different in the receiving set-up.
C48 is in Group C/D, but only just. If the aerial is quite old it might not work very well down at that frequency - the groups were extended to squeeze in Channel 5 when it launched in 1997. It might be worth going wideband now, as there may be new services as far down as C33 (although this has not yet been finalized).
This frequency hasn't ever been used before at Mendip. If this is a residential block with a communal aerial - bird's eye view on Bing suggests it might be - it could be a channelised system and the system would require retuning to amplify this channel rather than the previous location. The levels might need to be recalibrated too, even if it isn't channelised.
The overall signal levels are substantially increased since last week, and that could push a system that was working into having too much signal. See Freeview signals: too much of a good thing is bad for you | ukfree.tv - independent free digital TV advice for more information. (SP8 4AD) (SP8 4AD)
| link to this comment |
Mr. J Talboys: This can often happen if you use the 'automatic search' facility and the box has run out of permanent storage memory. Or, some boxes apparently don't overwrite the permanent locations with this facility.
At major retunes you are recommended to reset the box to a blank state, using the Factory Reset, Default Setting, 'Reinstall All Channels', Full Retune, First Time Installation or Virgin Mode options. Different equipment calls it different things. There are retune guides for some equipment, and full manuals for some others, at TV Re-tune .
| link to this comment |
sam: If it's an oval-shaped mesh dish, it's probably set up for the digital satellite services targetted at the UK. If it's older than 2001, it could be aimed at the Astra 1 cluster of satellites that was used for analogue signals before 1998 (these were switched off in 2001).
If it is the right dish, you can just plug in a Freesat box and it should work.
A dish can always be moved to point at a different cluster, and some viewers - particularly in northern Scotland - were recommended to get larger dishes or fully circular ones, so this isn't a sure-fire test of being able to just plug in and go. You can adjust the dish yourself with the help of tools like UKSatelliteHelp.co.uk - Satellite Dish Alignment / Setup Calculator 2.0 , but you may need a meter for best results.
| link to this comment |
Cavendish: Digital UK's postcode predictor gives you an excellent chance of getting a full service from the Belmont transmitter in north Lincolnshire. This transmits Yorkshire local news. The probability of reliable results from West Runton is shown as substantially lower and is expected to deteriorate after September 2012; it is your best option for BBC Look East and ITV1 Anglia, however.
You should actually be able to get four out of the six multiplexes from Belmont now; the other two are on low power to avoid interfering with services from Tacolneston. You would need a wideband aerial for all six once they power up, which happens after Tacolneston switches over.
Relay transmitters are usually directional, transmitting most of their power in one or two directions. Unfortunately, we don't know what the radiation pattern is. Given the distance between you and the transmitter, and the relatively high power level, I have to assume that there is quite a high restriction in your direction.
| link to this comment |
John de Carteret: See Will there ever be more services on the Freeview Light transmitters? | ukfree.tv - independent free digital TV advice for an explanation of why relay transmitters only carry some channels.
| link to this comment |
Graham Booth: Lower quality values after DSO - assuming that it's a grade out of 10 - is often an indicator of too much signal. See Freeview signals: too much of a good thing is bad for you | ukfree.tv - independent free digital TV advice for more information.
| link to this comment |
Looks like Channel 4 HD will be moving to Astra 1N when it gets into position:
News - SES.com
| link to this comment |
Briantist: Sudbury has a retune on 16 November. To clear C50 for Tacolneston, ArqB moves to C63.
http://www.digitaluk.co.u….pdf
It will remain at 2,200 watts.
| link to this comment |
Steve P: That information is out of date. It came from an Ofcom document (licensing section) that has been superseded and wasn't consistent with a different Ofcom document ('stakeholders' section). All sources now agree that ArqB has moved from C63 to C39, now that Emley Moor's early HD service is no longer in the way.
mycloud: Given you are practically on top of the Sheffield (Crosspool) transmitter, you probably do have too much signal. See Freeview signals: too much of a good thing is bad for you | ukfree.tv - independent free digital TV advice .
Do be sure that you have done a full factory reset, exactly as you should have done at switchover; many boxes simply can't handle a multiplex moving to a different frequency using the 'add channels' function.
| link to this comment |
Clive Jenner: I got that when Hemel Hempstead retuned a few weeks ago (14 September). HH simply retransmits what Crystal Palace transmits, so a change in the frequency information for HH had to actually be transmitted by CP.
I also have a PVR-9200T, but it hasn't prompted again since. Are you up to date? If you press MENU and go to System, Status, the versions should be:
System ID: 3020.0000
Application Version: PGXTF 1.00.23
Loader Version: A4.09
Update Date: 20th May 2010
If the versions are older than that, the current version is currently being rebroadcast. In the Software Update menu, make sure that it is set to automatically update at 4am. Make sure you put the receiver in standby before you go to bed, it will not update unless it is in standby.
That said, I think the change notification was only added in the that version.
As I recall, there are three options, Now, Later and something else. I pressed whatever would cause it not to retune at all, and never ask again (i.e. the third option).
Humax do recommend doing a Default Setting after installing that update. You might try doing one anyway. That will delete the future recording schedule and all channels, and all other settings - previous recordings are kept. I'd particularly advise moving the RF output away from its default as it clashes with analogue Channel 5 - I've set mine to UHF 53.
| link to this comment |
Mary: At that location, chances are extremely good that you have too much signal even without a booster. If you were much further away, I would say that maybe the reflector is too short, but you should be able to use an indoor aerial at that location (or no aerial at all) and still have excellent results.
A wideband is completely unnecessary at Crystal Palace and it's unlikely that it ever will become necessary.
Remove the booster completely, it won't be doing anything useful and could be harming the signal quality.
| link to this comment |
Stan Hill: Mendip has never previously used C48 or C52. If you are using a communal aerial, the distribution system might need retuning to amplify these channels instead of the old locations. If you had a similar problem in January when ArqB moved to C67, that's probably the issue now.
You might also or alternatively have another box, such as a Sky box or VCR, with an RF output on a clashing channel, most likely C43 or C47. RF outputs clash with the same channel, adjacent channels, and 5 and 9 channels higher. If you do, try turning it off if it's not used, or retuning it to C21 - this channel is unlikely ever to be used at Mendip.
| link to this comment |
Stan Hill: 813 isn't a standard location for any channel. BBC News should normally be on 80. Anything stored in the 800s is a duplicate of something else, and the order they get stored will depend on the order they are found or the relative strength, when you retune.
It could be an indicator that your box doesn't handle the larger Network Information Table, or other extended service information, correctly. Digital UK have a partial list of equipment known to have problems at http://www.digitaluk.co.u…tnit and more information for specific boxes at Digital UK Retail - Troubleshooting guides .
| link to this comment |
Chris.SE: A minor quibble, Oxford did not get a temporary mast to provide services while the main antenna was re-engineered. Instead the reserve antenna was used for all services. This is fitted *below* the FM radio broadcast aerials, which occupy a significant amount of space - the reserve is 55m lower down a 159m mast than the main antenna. This is the last resort should a future problem take out the main antenna or transmitters. The main antenna itself is designed in two halves and can be run on only one half, although (presumably) at reduced power. This redundancy is carried through to the combiner unit.
Unlike many sites, at Oxford, low-power DTT ran from the main antenna, plus an extra 'hat' on top of the old cylinder, with the possibility that a couple of multiplexes (1 and B) had an extra filler on the side of the mast, a little below the new reserve. That meant DTT was also quite seriously affected when the main aerial was being replaced.
| link to this comment |
KB: Lyngsat says Novasports are on Hotbird 8/9, 13°E. Encrypted using Irdeto 2 - you can get an Irdeto CAM to plug into a free-to-air receiver at a number of UK websites (or at least they're priced in pounds).
Funny how UK channels are on a satellite further east than the Greek channels!
Nova are well aware of this situation, they carry the English commentary (which I believe is the Sky commentary!) on a second audio stream. All adverts and match build-up and review are in Greek (or were a couple of years ago).
It does test your knowledge of the Greek alphabet to figure out which channel is showing your team's match... as I recall, it was in the two seasons when I was interested.
| link to this comment |
Suzanne: At 13km from a 100 kW transmitter you need a 14-element Yagi, tops. A 'contract' 10-element would probably have been fine. An indoor aerial will probably work well enough at this location.
I have to say that aerial looks pretty flimsy.
The difference between C60 and C59 at the moment is only 9 dB, there was a much bigger difference between adjacent analogue and digital channels before switchover (e.g. Channel 4 on C53 and Mux B on C52 differed by 19.2 dB).
The problem is that digital TV requires any amplification to be very linear - including automatic gain control and the internals of the tuner. If not, you get intermodulation - frequency-shifted copies of the signal in one channel, that then interfere with another channel. Most amplification circuits are approximately linear - near enough for reliable performance - in their designed input range. Go outside that range and they distort. It's that intermodulation that I think is happening to you.
IF your fitter had set up the signal levels at the recommended level for analogue, they should not now be so strong as to cause intermodulation. However, many fitters either set up the signals at the maximums for low-power digital, despite the large difference in levels between analogue and pre-switchover digital at Oxford, or just fitted the same aerial everywhere regardless of the requirements of the location.
Some boxes might have trouble with very different signal levels between multiplexes, say if their gain control circuits set the level based on the overall signal level, but then I would expect all the commercial multiplexes to fail, not just one. I didn't see very many reports of problems at Sutton Coldfield between stage 1 and 2 of DSO, which had the new BBC multiplex booming in at 200 kW on C40 and the old ITV1 mux (Multiplex 2) at 8 kW on C41 - a difference of 14 dB.
| link to this comment |
R Lees: It's cost.
In 2007, the two transmitter owners, Arqiva and National Grid Wireless, published Reference Offers for Network Access, basically sample contracts for transmitting a multiplex. In those documents, the public service broadcaster outline costs - in 2005 prices - were given as £24.7m per multiplex per year, while the commercial multiplex operators were quoted £10.4m. If the costs were shared equally across all six multiplexes, each would pay £17.5m, so an increase of £7.1m (+69%) for the commercial operators, for an increase of potential viewers of only 8.8%.
There are 80 main transmitters and 1,074 relays. The main transmitters are higher-power, but there's a substantial capital cost of equipment required at each relay site.
No, the licence fee is the same, there is no rebate. The licence is for operating or installing a television, the money raised goes mostly to the BBC, and the BBC's public-service channels are all broadcast from all transmitters.
The BBC does own - through BBC Worldwide - half of UKTV, which runs the Dave, Yesterday, Really and G.O.L.D. channels on Freeview, plus a few more on satellite. The revenue from advertising feeds back into the BBC public-service broadcasting budget.
| link to this comment |
Richard: I'm not sure what Mendip clash you're talking about, Mux 2 at Oxford was adjacent to Mendip Mux D before switchover, and the two stations ran like that for ten years since March 2001. Both got subsequent power increases, Oxford in August 2002 and Mendip some time in mid-2003. From January this year, Mendip C67 had a power increase from 10 kW to 26 kW so ArqB could launch in final mode, restoring Sky Sports. This would presumably be the upper limit that could be used.
People out in Swindon might have had a problem on occasion with adjacent channel interference (caused by filtering being imperfect - in the real world, some leakage into adjacent channels is inevitable - and a little cost-saving on using less complex filters where there isn't an adjacent channel at the same site). Someone in or near Beckley itself would be unlikely to have this problem except in incredibly rare weather conditions.
I'm really not sure what your issue was - some local source of interference does seem the most likely. If you're having increased problems now - the same on all multiplexes - I'd look into sources of impulse interference like a thermostat or other motor.
| link to this comment |
Mike Bryce: Most likely explanations are either an overlap, with the box tuning in the wrong transmitter, or too much signal. See Digital Region Overlap and/or Freeview signals: too much of a good thing is bad for you | ukfree.tv - independent free digital TV advice .
| link to this comment |
BobH: Existing recordings are preserved when you use the 'Default Setting' option, which is recommended with major retunes. In the latest firmware 1.00.23, 'Automatic Search' is supposed to be equivalent for retuning, but I still found scheduled recordings could be unreliable unless you delete the schedule and re-create it.
Default Setting resets all other preferences, so you will have to reset the output format option (reverts to 4:3 with letterboxing), the UHF output channel, and the recording schedule (that being the minimum that I do).
| link to this comment |
M
Nottingham (Nottinghamshire, England) Full Freeview transmitterThursday 6 October 2011 2:54PM
Nottingham
Pixelated: If you had reliable results before switchover, you could have too much signal. I can't advise any more on that or on the possibility of using Waltham without a full postcode.
At NG12 3JL - roughly the centre of Cotgrave - Waltham gives a better chance of reliable reception than Nottingham, or at least will do after the SDN multiplex reaches full power next Wednesday. You would need a wideband aerial for all multiplexes. It looks as though that postcode is shielded slightly by the terrain, so a higher-gain aerial is probably necessary, and I would recommend an outdoor aerial.
ian from notts: Yes, Emley Moor and Nottingham now use the same frequencies for the SDN, ArqA and ArqB multiplexes, since the retune on the 27th. I don't think these are actually co-ordinated so will interfere with each other in some areas.
| link to this comment |
John Morris: The cable insulation is plastic and like all plastics, it deteriorates with exposure to sunlight, and can then let damp in. White insulation tends to be affected worse than black or brown.
Cables should be anchored at frequent intervals, including clips over tiles, so that they cannot move in the wind and rub over the brickwork or tiles, which wears through the insulation.
I'd say you should plan to replace cables about every ten years.
| link to this comment |
Willie Donaghy: The number of transmitters and power levels for Freeview, before switchover, was necessarily limited to avoid interactions with the Republic. That's why take-up of digital in Northern Ireland has been relatively poor.
It means digital coverage from Limavady isn't anywhere near the analogue coverage area. Four of the digital multiplexes also clash with the Claudy relay. I'm not surprised that it's unreliable out where you are, although Digital UK's postcode checker isn't currently accepting your postcode so I can't see the actual prediction.
Aerials and cables do deteriorate over time with weather exposure, and if water gets into cables, it seriously degrades the cable's performance - and higher frequencies are affected worse than lower ones.
At switchover, the PSB digital transmissions should have parity with the current analogue transmissions, or slightly better. The commercial multiplexes will still only transmit from Divis, Limavady and Brougher Mountain and will be half the power - but that still means they should be nearly the same coverage as analogue, except for a few areas where channels clash with the PSB channels from a relay (Plumbridge and Castlederg).
It looks like switchover is about a year away, stage one on 10 October 2012 and stage two on 24 October. This is based on a leaflet that briefly appeared on Digital UK's website on Friday - my guess is that the announcement is supposed to be on Monday or Tuesday and someone pushed the leaflet out too early.
| link to this comment |
K W: I assume you mean Freesat-from-Sky as Freesat does not require a viewing card.
You can set up parental controls on all Sky boxes. See Sky TV | Set up for the manuals for each different type of box, which will show you how to do this.
They do say that the default PIN is the last four digits of the viewing card's serial number - if you don't have the card, and you haven't set the PIN to something else, you will need to contact Sky to find out what it was or to get it changed.
| link to this comment |
Phill: Saorview launched at the end of last year.
A Freeview HD receiver should implement MPEG-4 AVC on DVB-T, which is required to receive RT 2 when it's broadcasting in HD, even though at present the UK only uses MPEG-4 AVC on a DVB-T2 multiplex.
For interactive text, the Irish standard permits either MHEG-5 as used in the UK, or the legacy teletext system. Freeview HD equipment is not required to implement legacy teletext.
You can check to see whether the address you'll be using the equipment at is covered by going to Coverage Map | SAORVIEW
| link to this comment |
Graeme Young: Yes, BBC A on C61 will have to move, as C61 and C62 are now to be released for 4G mobile in addition to C63-C68 in the original plan. All stations with greater than 1kW ERP output are subject to international co-ordination - although the plan from 2006 shows that Waltham did not need to be co-ordinated with anyone else. Still, the co-ordination required for other sites like Tacolneston, Mendip, Wenvoe (not itself affected directly but it might have to move out of the way of Mendip) means that Waltham is unlikely to make an earlier move than other sites.
C21-C30 are retained for TV broadcasting - they are not going to force the 4.4 million Londoners using Crystal Palace to all buy new aerials (well, unless they're completely mad). The SDN multiplex on C29 is very unlikely to have to move.
You may need to retune the SDN multiplex early tomorrow, as it reaches full power and changes to 8K mode. Changes are supposed to be complete by 6am.
| link to this comment |
Craig: Boosters are typically no use whatsoever. They are only of any use if the receiver is particularly noisy, and most Freeview boxes will actually be less noisy than an added booster.
The prediction at your address is 100% across the board, suggesting that the problem is actually too *much* signal. See Freeview signals: too much of a good thing is bad for you | ukfree.tv - independent free digital TV advice .
| link to this comment |
Nicholas: The standard Freeview EPG is transmitted on all multiplexes. Each multiplex transmits its own information more frequently than others, and information about programmes coming up sooner more frequently than later events, but it does all get sent and repeat after a few minutes. Some boxes can get very confused with a mix of different services from different transmitters.
I'd start off by doing a full reset or first-time installation with the aerial unplugged, then doing a manual search for the transmissions from your most preferred transmitters. If that is then reliable, do a manual search for just the regional services (BBC A and D3&4) on your second preferred transmitter, which will put those services in the 800s. If it stops being reliable after that, you'll know where the problem lies.
Some equipment does still use a proprietary EPG. Top-Up TV's EPG is attached to TOPUP Anytime 1, Guide+ to bid.tv, and RadioTimes Extra to Television X. All three are on Mux A/SDN.
| link to this comment |
Paul: Ofcom's official documentation of Sutton Coldfield's frequencies was re-issued in January this year, to move BBC B's allocated channel from C50 to C40, and ArqB from C49 to C39. This is part of the plan to free C61 and C62 for 4G mobiles - basically C39 and C40 were going to be freed but are now kept. However, a direct move from C62 to C40 or C61 to C39 would affect a lot of people, as they aren't in the same group, so the compromise is *generally* to move allocations of C62 to C50 and C61 to C49, and move C50 to C40 and C49 to C39, where there is a clash.
Yes, this means there will be another retune at Oxford some time in the next two years, to move SDN from C62 to somewhere else, although it *should* remain in Group C/D.
Hannington C50 isn't particularly low at 20kW, that actually made it joint equal most powerful pre-switchover transmitter, with Crystal Palace, Rowridge and Sandy Heath! Post-switchover PSB power levels are only 4 dB higher at 50 kW (COM power levels are 1 dB higher than at present, 25 kW).
| link to this comment |
Chrisonahill: The signals from Beacon Hill are at their final power levels. It's unlikely that there will be further power increases.
If your location is still BH20 6JG, I would guess that Rowridge on the Isle of Wight would give better results than either of the mentioned transmitters, once it switches over in March. You're likely to get best results using a vertically-polarized Group A aerial, once the VP services are running at full power from 18 April 2012. The commercial multiplexes from Rowridge will use the same channels as Stockland Hill, which will have some effect, though the use of VP should help (as Stockland Hill is horizontally-polarized).
Your reception of commercial multiplexes from Stockland Hill is liable to be clobbered by Rowridge once it completes switchover, even with Stockland Hill's power increase, and Rowridge's horizontally-polarized COM transmissions being one quarter of the power of VP.
Please note that this is my guess, rather than a prediction from Digital UK, whose website is currently not accepting that postcode.
| link to this comment |
John Hodgson: Stow is a 'Freeview Light' transmitter, broadcasting only the public-service multiplexes. The channel line-up should be:
1 - BBC One Scotland
2 - BBC Two Scotland
3 - ITV1 Border Scotland
4 - Channel 4
5 - Channel 5
6 - ITV2
7 - BBC Three
8 - BBC Alba
9 - BBC Four
13 - Channel 4+1
14 - More 4
28 - E4
33 - ITV1 +1
70 - CBBC Channel
71 - CBeebies
80 - BBC News
81 - BBC Parliament
301 - BBC Red Button
and a number of BBC radio stations and text services.
Please see Will there ever be more services on the Freeview Light transmitters? | ukfree.tv - independent free digital TV advice for the explanation (short version: cost).
| link to this comment |
Matt: The numbers are the percentage of locations, within the 100m x 100m National Grid square that the centre of your postcode falls into, that are predicted to have (on average) sufficient signal margin to be reliable 99% of the time, and 50% of the time, respectively. It's a measure of the difficulty of locating an aerial within that square and how coverage might vary between you and your neighbour.
The prediction is based on an aerial with CAI Standard 1-class gain, and loss of 3-5 dB in the cable depending on frequency, but the template for cross-polar and front-to-back rejection is weaker than such an aerial would normally achieve. The prediction allows for losses if the signal path goes through a square made up mostly of woodland or of dense buildings but it only allows for average losses. They might be higher or lower than allowed for.
The prediction calculates both the signal from the wanted transmitter and the interference from unwanted transmitters, including adjacent-channel interference.
Short of actually going and surveying every grid square in the country, this is probably the best we can do, but it's always going to give 'wrong' answers for some people.
| link to this comment |
Neville Wake: Upscaling cannot create resolution that didn't exist in the original content. An upscaler is only of any use if the upscaler in your TV does a poor job.
Freeview HD channels broadcast (mostly) content that was recorded and processed in HD. The BBC HD channel carries only HD content, the others have a mix of HD and upscaled content depending on how it was sourced. The majority of new programmes are made in HD. The EPG information for BBC One, BBC Two, BBC Three and BBC Four ends with 'Also in HD' if the programme was made in HD and is being simulcast on BBC One HD (for BBC One content) or on BBC HD (Two/Three/Four).
Giles: Ofcom are still deciding what to do with UHF channels 31-37 after DSO completes. The transmitter provider Arqiva have been asked to prepare a Reference Offer for broadcasting up to three new multiplexes using this range of channels; the predicted coverage is lower than for the current six multiplexes. The new capacity could be used for SD or HD channels - that will be up to whoever bids. Ofcom could still decide to release these channels for services other than TV broadcasting.
Over time I would expect the existing multiplexes to be upgraded to DVB-T2 in order to get more capacity from the same spectrum, though DVB-T is likely to remain around for quite a while.
| link to this comment |
Briantist: Digital UK's postcode checker is now showing 'COM Mux FEC Change' on various muxes at various sites, over the next couple of months. Hovering over ArqB for The Wrekin shows a change from 64QAM 2/3 to 64QAM 3/4.
It's possible that this will be accompanied by an increase in the guard interval, aiming to improve coverage by turning co-channel interference into SFN; I notice that Hannington and Crystal Palace now show all three COM muxes going to 64QAM 3/4 at switchover, and CP COMs are co-channel with Rowridge. The net capacity is likely to be the same, if that's the case.
64QAM 3/4 8K 1/8 has a fraction more capacity - 24.88 Mbps - than 64QAM 2/3 8K 1/32 (24.13 Mbps).
| link to this comment |
Peter Henderson: Digital UK did publish a brochure stating 10th and 24th October 2012 on their website, but the site was reverted to an older version. There could still be an announcement in the next week or so, much longer and it's probably further delayed.
Black Mountain is the old IBA VHF TV mast - Divis was the BBC mast - and has plenty of aperture for a high-power antenna. Channel 5 analogue transmits at 50 kW, apparently from a skew-fire array at the top of the 228 metre mast. A cantilever could perhaps be added if required, or RT could take over the C5 array, depending on how flexible it is and whether it might be needed for MUX 7, 8, 9.
It may be that the new Divis mast wasn't designed to take the weight of the RT mux antenna in addition to everything else, assuming that for whatever reason the PSB or COM main antennas can't be used.
| link to this comment |
Andrew Clinton: The only engineering work was this morning, bringing the SDN multiplex up to full power and on the main broadcast antenna. This shouldn't have had any effect on reception of HD channels, unless you were close to having too much signal before, and the additional power on the SDN multiplex has now pushed it over the edge.
See Freeview signals: too much of a good thing is bad for you | ukfree.tv - independent free digital TV advice for more.
| link to this comment |
P Smith: Sudbury's next stage is to move ArqB - which carries Yesterday - to C63 on 16 November, to get out of the way of Tacolneston's high-power digital transmissions on C50.
The final channels and power levels will be reached on 27 June 2012, after Dover has stopped using them - the Meridian East region completes switchover on this date.
Digital UK's predictor suggests that your reception of ArqB should be improved when it moves to C63 in mid-November.
| link to this comment |
Ian: Sky would waive the fees because they don't want a full investigation into their subscription business. Sky take most of the money off the top of the regular entertainment pack subscriptions and use it to subsidise the sports and movie packages.
| link to this comment |
Ian: Sorry, I misread the headline, assuming something that I shouldn't have, that Sky had decided to do so.
The fact is, Sky charge the channels a 'Platform Contribution Charge' which has nothing to do with the costs incurred - it is weighted to the share of viewing. This is actually the majority of the money, the BBC being charged £9.89m overall, £4.78m for BBC One alone. The platform is very well-developed and this charge should be entirely dropped, for all channels.
The actual EPG charges per EPG slot are outrageous too, costing approximately one average worker's salary per slot. I can't believe that it takes anything like that much to manage the flow of EPG data, particularly for the BBC which is very well set up for metadata, since they feed Freeview, Freesat and cable services in addition to Sky.
The regionalization component is something like £2-3m - I couldn't figure out exactly what rules Sky were applying.
| link to this comment |
Stuart Dunn, z: Freesat receivers may have a Common Interface (CI) or CI+ slot. This slot takes a Conditional Access Module, which performs the decoding according to the algorithm programmed into it. The CAM requires a card which contains the decryption keys.
Unfortunately, Sky's Videoguard system (owned and operated by a News Corp subsidiary) is not available as a CAM, so you cannot use anything other than a Sky receiver for their services.
z: I'm not sure how a foreign channel got linked to your Sky subscription in the first place.
| link to this comment |
Mitchell: Hannington's low-power digital broadcasts are seriously restricted to the north-east, east and south-east. This is because they currently use the same channels as the Guildford analogue transmissions. The main ITV/C4/C5 multiplex - which carries ITV1, ITV1 +1 and ITV2 - uses a less robust transmission mode that is more likely to have problems with this clash.
Digital UK currently show no prediction for five out of the six multiplexes from Hannington, for your postcode.
At switchover, the digital services take over the main antenna, which has no restriction.
You should *not* upgrade your aerial to attempt to get the services. If you do, you are likely to end up with too much signal when it does happen.
Switchover starts on 8 February 2012 - analogue BBC Two switches off, Mux 1 switches off, new high-power BBC A starts on BBC Two's old frequency - and completes on 22 February. The commercial multiplexes remain on the low-power digital antenna until the London DSO on 4 and 18 April 2012, as they still clash with Guildford until those dates.
| link to this comment |
Anne White: There are two meanings of 'channel'. One - which this map relates to - is the frequency that the TV service or multiplex is broadcast on. That's the 'UHF Channel' - around here we usually prefix it with a C, e.g. C50. The other is the number you enter to watch a particular service. That's the 'logical channel number'. It's a suggestion that the box is supposed to follow, but if there's already a service stored at that location, it can put the service elsewhere.
With the analogue system, one analogue TV service was transmitted in one UHF channel, so the name 'channel' started to be used for the TV service. Digital services are carried in a 'multiplex', a combination of multiple services in a stream of data, to share some of the overheads of digital encoding and error correction. One UHF channel contains an entire multiplex, which carries anywhere from six to twelve services.
Hannington broadcasts Multiplex 1, which carries the majority of the BBC's digital services, on UHF channel 50. The exceptions are BBC Four, CBeebies and the radio services.
Logical channel number 50 is BBC One HD, at sites that are broadcasting the HD multiplex. This is transmitted in a slightly different way to the other services, which requires 'Freeview HD'-branded equipment. The HD multiplex starts up at the second stage of switchover, except for a few locations that were particularly important to the advertisers (London, Birmingham, Leeds, Newcastle, Glasgow and Edinburgh), where an early service started in 2010. Hannington will start transmitting it from 22 February 2012.
One of the early HD services is from the Crystal Palace transmitter which serves the London area. Some people in the Hannington analogue coverage area can already get HD from Crystal Palace, with the right aerial pointed in the correct direction. I'm not sure it's worth changing with only a few months to go, though.
You will need to retune your Freeview box or TV on 8 February and 22 February. The analogue services shut down, and the high-power digital services take over the old analogue UHF channels. These channels have much less interference than the channels currently used for digital services. Indeed Hannington's digital broadcasts are currently heavily restricted to the east, because the current channels clash with analogue broadcasts from the Guildford transmitter.
| link to this comment |
Alan Robinson: If they had reliable reception before switchover, the signal levels could now be too high.
The communal system probably needs adjusting to ensure that the levels on each channel are correct. It might even need replacing if it's particularly old.
See PARAS - Professional Aerial Riggers Against The Sharks for advice on who to contact.
| link to this comment |
Steve: You previously said you were at DE4 3ET, is that still the case?
Digital UK don't offer any prediction from Waltham at that address. A look at the terrain shows some very big hills blocking line-of-sight. While signals do refract over terrain, they will always be weaker than if you did have a direct path available.
The Bolehill relay also transmits on C57 and could be generating enough interference to stop the weak signal from Waltham getting through. The problem on C56 is less clear, although it could be down to being adjacent to the HD multiplex from Stanton Moor on C55, and the C57 service from Bolehill.
The broadcasters use antenna diversity - more than one antenna used in an array, or at different heights on the mast - to handle such problems. You *can* do this yourself, but it can be expensive. It's usually a lot easier to go with a satellite service. You can compare the channels available on Freesat, versus Freeview, at Compare Freeview and Freesat TV | ukfree.tv - independent free digital TV advice .
It *is* possible that you have too much signal, which often causes problems for adjacent channels on a transmitter. You did try turning the amplification *down*, not up?
| link to this comment |
Briantist: You still have 'Huntshaw Cross B' in the system - the Huntshaw Cross region page puts this on top of Huntshaw Cross, so a click shows a green coverage area and a double-click takes you to the Huntshaw Cross B page.
| link to this comment |
Ofcom's 'Table of Digital Stations for Multiplex Licences' shows Mux D on C52 running at 640 watts since 28 September 2011. This is presumably to deal with the added interference from Mendip ArqB moving to this channel on the same date.
| link to this comment |
Keith: You'd have to provide a full postcode to see exactly what's available.
The Gorleston-on-Sea transmitter starts to switches to digital on 9 November 2011 (BBC Two switches off, BBC digital services start up), and 23 November (all remaining analogue channels switch off, ITV/C4/C5 digital services and HD services start up). It will be a 'Freeview Light' transmitter, providing only the public-service multiplexes.
The commercial providers are not extending their services to more sites. See Will there ever be more services on the Freeview Light transmitters? | ukfree.tv - independent free digital TV advice .
| link to this comment |
Steve P: As I recall, Sky+ cannot perform scheduled recordings from channels in the 'Other Channels' selection, which viewers would have to tune in manually if the BBC were to move off the EPG.
It's a bit of a legal grey area, because the Communications Act 2003 (IIRC) requires the EPG provider to carry the public-service channels, but doesn't say anything about charges.
| link to this comment |
Phil: Can you provide a full postcode please?
If anything, Oxford's switchover should have *improved* your reception of Crystal Palace Mux C, because Oxford no longer uses C34. This channel is one of those being cleared for the "digital dividend" so no transmitters have started up digital services on this channel after switchover.
I can't say I'm having any issues with Mux C in Reading, or at least no more issues than before.
| link to this comment |
David Rose: At that postcode, this change probably won't give you any more channels. The multiplex carrying Film4, ITV4, Yesterday (ArqB in the list above) moves to a different channel to get out of the way of Tacolneston's switchover; the power level remains the same. If you already get those channels, you will need to retune to keep them. The higher frequency used travels less well, so it's possible that, if your reception of them is a bit marginal, you could lose them or they become less reliable.
The final move is on 27 June 2012, after which Digital UK offer a prediction of 'good' for the SDN and ArqA multiplexes and 'variable' for ArqB. The final channels cannot be used yet as they are still in use at the Dover and Bluebell Hill transmitters.
| link to this comment |
spencer: The last update for the Humax HDR-FOX T2 was in June 2011, version FHTCP 1.02.20. If you missed the over-the-air update, you can download it to a USB memory stick, then plug that in to the box to update it.
If you already have that version, you'd have to ask Humax whether they have any updates in development.
| link to this comment |
Zak: Is the aerial optimized for Idle? It should be oriented with the elements running up-and-down, not side-to-side, and pointing north-east.
The prediction at the moment is poor, because the low-power services from Bilsdale use the same frequencies as Idle (the three PSB multiplexes and the SDN mux), and the two transmitters are in very nearly the same direction for you.
| link to this comment |
Jordy: Denis Wolinski | LinkedIn
Formerly Ofcom chief in Northern Ireland, and before that Northern Ireland head of the Independent Television Commission, Ofcom's predecessor.
Presumably the job was externally advertised due to a policy, but I'd guess there was little chance anyone else would get it!
| link to this comment |
Briantist: See Intelsat 907 (27.5°W) - All transmissions - frequencies - KingOfSat .
It carries four national variants of BBC One, one of BBC Two, and all the other parts necessary to assemble both pre-switchover Mux 1 and Mux B (less Sky Sports), and post-switchover BBC A. Significantly it has 301 on there.
In addition, it carries the commercial HD channels ITV1 HD, Channel 4 HD, S4C Clirlun and STV HD, in order to assemble BBC B.
As for the service type identification, I would think that's deliberately wrong to stop your average home decoder from tuning in.
| link to this comment |
Fabian: Digital UK suggest that the best option for you is the main Crystal Palace transmitter, which is roughly south-south-east (162°) and 16 km away.
It's very likely that your neighbours' aerials are already facing that direction.
Do be careful of aerials advertised on the Internet and in DIY stores. There is nothing 'HD' or 'Freeview' about any aerial. An aerial *might* be termed 'digital' if it has a balun, a device that better matches the properties of the aerial to the properties of the cable; cheaper aerials designed before digital started might not have had a balun, but an aerial not labelled as 'digital' might still have one.
I assume, by the way, that you're talking about a roof aerial. Indoor aerials can almost never give as good a result as a roof aerial - the elements are always under-sized, UHF signals don't travel well through walls and signals will be attenuated by having to come through neighbours' walls. A small aerial designed for a roof-top can work in a loft, but it's still advisable to put it outside if you can.
| link to this comment |
jb38: The only thing I'll add is that the transmitting antennas always have a vertical component to the radiation pattern, the main lobe being aimed at or slightly below the horizon - this is termed the 'beam tilt'. The more tiers in the broadcasting aerial, the narrower this main lobe is. Efforts are made to ensure that there are no nulls.
The beam tilt is basically there to reduce the reflections off the upper atmosphere, causing signals to travel far further than designed - it's also a huge waste of power if much of the transmitted power escapes the intended service area!
The old main antenna at Sutton Coldfield is described in BBC Research Technical Report 1967/19 BBC RD - Publications - R&D Report 1967-19 : UHF transmitting aerial for the Sutton Coldfield television station . The VRP on the south-east face (appropriate for Jack's location) is on p15. At 12km away the angle is about 1.5° below horizontal. At this angle I guess (by eyeball) it delivered about 65% of full strength, which would be about 3.74 dB down (field strength is expressed as a voltage, not power, so multiply the log by 20, not 10). Because it's linear, the graph exaggerates the level of attenuation with increasing angle.
The attenuation in free space is much greater than this, though - using the calculator at Field Strength Calculator gives a value of 12.4 dB difference in path loss for distances of 12 km and 50 km, on C40. Net, the actual field strength at 12 km away is still 8.66 dB greater than at 50 km away.
Of course, we don't know what the VRP of the new aerial is. It may or may not be similar, depending on exactly what coverage area was targetted. Each aerial was a custom build to Arqiva specifications: we know this due to the lead time on the second new aerial at Oxford, after the first was destroyed by fire. They are manufactured by RFS from PHP panels, four to a tier, and standard array patterns are given at the end of http://www.rfsworld.com/d….pdf (the top-mast is two independent 6-tier arrays, one for the PSB multiplexes and one for the COMs).
| link to this comment |
Chrisonahill: If you click the number of posts next to a user's name (yours currently says '10 posts'), you can see that user's previous posts. A post attributed to you had a BH20 postcode attached.
Looking at the prediction for your postcode, it still looks like a significant interaction between Stockland Hill and Rowridge. Indeed the prediction for Rowridge VP COM muxes (after April 2012) is still better than for Beacon Hill - ArqA and ArqB, at least.
I can't really see why the prediction for ArqB is so poor, there aren't that many other sites using C51, although one of them is Redruth, which is in the same direction as Beacon Hill and double the distance, and has equal power. The poor predictions for C42 and C45 may be because they're adjacent to the PSB muxes at Redruth.
| link to this comment |
Chrisonahill: And C42 and C45 are also adjacent to the PSB transmissions from Weymouth and Charmouth transmitters.
| link to this comment |
Dave: Yes, for Freesat. The assumption is that they're only currently encrypted due to rights issues, that they can't broadcast free-to-air across the whole of Europe without paying a lot more money. If that assumption is true, it follows that if they move to a British Isles footprint, it's because they want to go free-to-air.
ITV2, 3, and 4 HD are currently on Astra 2A's north beam - the footprint is at https://sat.ses.com/webse…5753 . The current Freesat channels are on Astra 2D, which only covers the British Isles - see https://sat.ses.com/webse…5243 . Astra 1N's expected UK footprint is https://sat.ses.com/webse…5209 .
The new satellite has 52 transponders which could mean capacity for up to 200 new (or moved) HD channels, though a lot of the frequencies overlap with those already in use on one of the other satellites already in the cluster. We don't know how flexible it is, how many of the transponders can use the UK spot beam and how many can only use the pan-European beams.
| link to this comment |
guy: A Freesat box will give you BBC, ITV, C4 and C5 satellite services with no subscription. You can compare the channels available on Freeview (TV through an aerial), Freesat (no subscription, free choice of box), and Freesat-from-Sky (Sky boxes only, requires £££ for recording and time-shifting) at Compare Freeview and Freesat TV | ukfree.tv - independent free digital TV advice .
| link to this comment |
MarkR, stevea: I had to resort to watching the F1 on my laptop as both analogue and digital were poor. I think it was down to atmospherics - it was quite foggy on Sunday morning - rather than any work on the transmitter. (I wouldn't want to be up a mast at 6am on a Sunday, would you?)
| link to this comment |
Briantist: Chelmsford C5 is a bit of an exception as it belonged more to the London region than to Sudbury, but it went off at Sudbury DSO 2. Still, it *was* an exception.
According to the last timetable published by Ofcom, Channel 5 analogue must switch off by 31 December 2012, but it also still says that for the UTV region as a whole.
I think it's unlikely that analogue C5 from Black Mountain would be switched off before the DSO date.
| link to this comment |
Algernon Black: Because the switchover programme is still in progress, a later change at another transmitter can affect some viewers. If they'd switched everything over in one go, this wouldn't have happened - and you'd never have noticed.
Most likely you're in the south or south-east of the coverage area, near High Wycombe, Assendon or Chisbury. Those three transmitters' PSB multiplexes will clash with Oxford's COM multiplexes. The commercial multiplexes are not required to meet any specific level of coverage and certainly not to match the PSB multiplexes, which are required to substantially match analogue coverage.
'Variable' reception in Digital UK's postcode checker does not necessarily mean variable results. It means that using their aerial model, the percentage of locations that should, on average, have reliable performance 99% of the time, is below 70%. It means siting an aerial to get reliable results will be more difficult than if the 'good' standard was met. The aerial model is quite pessimistic, compared to real aerials, regarding rejection of signals from other directions and from the other polarization (those relays will transmit vertically-polarized signals and Oxford uses horizontal polarization).
High Wycombe and Chisbury already use C55/C59/C62 for their analogue transmissions, but a digital service does do more damage to another digital service than an analogue one does. Assendon uses C55 now and will start using C59 and C62 at switchover.
If you do find you are affected, you may be able to fix the problem by rotating the aerial slightly towards or away from the interfering transmitter - real aerials have peaks and troughs in their 'polar response' - how much signal is picked up from different directions - and you may be able to drop the interfering signals into a trough in the response.
| link to this comment |
barry: Most likely power to the distribution amplifier failed - perhaps a blown fuse or tripped circuit-breaker? Report it to the landlord or management agent.
At that location, I would expect an indoor aerial to be pretty reliable.
| link to this comment |
For reference, VLV is Voice of the Listener and Viewer (VLV)- the campaign for Public Service Broadcasting. and the event was titled "UK Programme Production - Securing its Future".
| link to this comment |
Chris Onion: At that postcode, there is a poor prediction for the ArqB multiplex - which carries Sky Sports 1 and 2 - from Waltham. The prediction for Sutton Coldfield is very good.
Digital UK never explain their predictions in detail, but there are a number of relays in the vicinity (Bolehill, Repton, Winshill) that transmit on C57. Levels of signal both from the wanted transmitter and from interfering transmitters do vary over time and not necessarily in line with each other.
If your aerial points south-east to Waltham, you may get better results by pointing south-west to Sutton Coldfield. You would still get East Midlands BBC One and ITV1 from the Derby relay - providing East Midlands service to people better covered by Sutton Coldfield is the reason that it exists.
In both cases you should check that the box has actually tuned in services from the wanted transmitter. See Digital Region Overlap for more information.
Given that the prediction from Sutton Coldfield is 99% across the board, and that you say it was OK before switchover, chances are that if there is a signal level problem, it's too much rather than too little.
| link to this comment |
Briantist: Yes, but that's not yet in the Digital UK postcode checker. If the conclusion is that the interference from those relays doesn't significantly affect that many Oxford viewers, chances are that Oxford and those relays will be moved to the same channels.
Ofcom's latest 'Table of Digital Stations' (version 5) now has High Wycombe and Assendon BBC B, and Chisbury BBC A, using C50 rather than C62 from their DSO dates. So perhaps that isn't the source of interference, or not the whole story.
The next nearest transmitter using the same channels is Midhurst, and of course this is a relatively high-power main transmitter using horizontal polarization. The variable reception prediction may just reflect lift conditions. At present C55 is an analogue channel at Midhurst, C59 and C62 are low-power digital multiplexes.
| link to this comment |
trevorjharris: The point is not that Sky viewers are having to pay for what others get free, it is that *Sky is charging the broadcasters for what other platforms give away*.
Each Sky viewer costs the broadcasters money, money that they do *not* recoup from subscription revenue. Free-to-air channels don't receive any payments from Sky's subscriptions, nor do 'free-to-view' (encrypted, but available to anyone with a viewing card even without an active subscription). Only the channels actually listed in the Entertainment Pack or Entertainment Pack Extra do. Even for them, Sky's Platform Contribution Charges will often exceed the revenue earned.
| link to this comment |
Kate: Sky charge the BBC and therefore the 60% of licence-fee payers who DON'T use Sky a 'Platform Contribution Charge' that Sky use to subsidise their boxes. This charge is related to the percentage of viewing of each channel. It is in no way fair, reasonable or non-discriminatory and should be eliminated.
The charges for appearing in the EPG should be related only to the costs directly incurred in running the EPG, and should be shared fairly between all channels, the PSBs should not be charged more than other channels as they are now. I do not believe that it costs an average worker's salary to maintain an EPG slot, even allowing for other costs of employment - Sky should be forced to account for the actual costs incurred.
| link to this comment |
Mark Fletcher: Caradon Hill doesn't use those frequencies, but Rowridge and Crystal Palace will do.
| link to this comment |
Mark Fletcher: Sorry, I managed to get Caradon Hill and Beacon Hill mixed up. Still, the reason for Stockland Hill's restriction is more to do with Crystal Palace low-power multiplexes than to do with Caradon Hill high-power.
Yes, there will be some interference between Stockland Hill commercial muxes and Caradon Hill PSBs. In general, though, the more rugged terrain means that there will be less of a clash than between Stockland Hill and Crystal Palace COMs.
| link to this comment |
Chris Onion: The only real way to check is to see what UHF channel numbers are in use. I'm not sure, because BT's documentation is maddeningly thin, but these might be displayed in the 'DTT Signal Strength' screen. Try selecting this option when tuned to, in turn, BBC One, ITV1, ITV3, Pick TV and Yesterday and, if available, BBC One HD and see if a UHF channel is listed. Check whether the channel is the same when tuned to Yesterday and to Sky Sports 1.
The channel numbers should match those above for BBC A, D3&4, SDN, ArqA and ArqB respectively (plus BBC B for HD services). If the box has tuned to the Derby relay, you would see C48 for BBC A, C51 for D3&4 and C52 for BBC B (again, if you have HD).
That signal strength screen will also indicate if you have too little or too much signal. If it's showing 100% strength, it's probably too much. If you have a booster, you should remove it. If that doesn't reduce the displayed level or if you don't have one, try adding an attenuator.
If signals were too distorted, the box may have tuned to the Waltham signals instead. Boxes usually tune the strongest, the best quality, or just the first found, depending on the software in the box; however, for you, Sutton Coldfield should be both the strongest and, except for a few multiplexes before switchover and one now (SDN), the first found as well. If the box has tuned to Waltham, you will probably find the signal quality gets worse - do try a full retune following the instructions at How do I scan for Freeview channels? | Help | BT.com Help .
Before switchover, Sky Sports 1 and 2 were carried on the BBC's second multiplex, Mux B. This was on a lower frequency at Waltham than the equivalent service at Sutton Coldfield, so it could be that your box decided to tune that in rather than the SC service - explaining the loss of service when Waltham switched. However, I would expect that to have affected the whole of Mux B (BBC Four and CBeebies, BBC Parliament, BBC radio stations) and not just Sky Sports. Indeed I would also have expected it to affect Mux 2 and A which were also on lower frequencies than the Sutton Coldfield counterparts.
There's a thread on the DTT Signal Strength display at DTT Signal Strength - Technical Question - BTCare Community Forums .
Digital signal levels from Sutton Coldfield were relatively low compared to analogue, so the increase at switchover was very large. The new levels were designed to provide good coverage *without* changing the aerial. If the new, as you say, 'massive' aerial was selected and set up for the pre-DSO levels it could well have led to too much signal now.
| link to this comment |
Mark A: Two EPG slots, so two charges. They are also listed separately in Annex 1 due to being audited separately by BARB.
The EPG slots cost £21,000 each; the Platform Contribution Charge is the large bit:
BBC Three: £871,045
BBC Four: £271,615
CBBC: £299,715
CBeebies: £776,750
Assuming that the aggregate viewing figures didn't drop for each segment of viewing, I would assume that the same total would be charged under your scenario as now.
Also, I don't think the BBC channels appear at the same EPG numbers in the Republic of Ireland EPG, so the charges in section B4 probably apply as well.
| link to this comment |
Ian Grice: BY LAW Sky, and all other EPG providers, must put BBC One, BBC Two, ITV1, C4 and C5 at the top of their EPG. The idiots who drafted the law forgot to set down any rules about how much the EPG providers are allowed to charge for the privilege.
As previously stated, the majority of the charges are for 'platform contribution' (box subsidy), NOT for carriage in the EPG, although the complexities of different regionalization arrangements for different broadcasters means the number of sub-bouquets - and the charges for appearing in each one - has exploded.
Are YOU happy for your licence fee to subsidise new boxes for new Sky subscribers? I don't object to boxes being subsidised from the subscriber's own subscription fees - a hire-purchase model, like mobile phones - I DO object to the licence fee being hijacked for the purpose.
| link to this comment |
I would expect that any frequency changes would be published in the ITU Radiocommunication Bureau's International Frequency Information Circular before Ofcom publish.
http://www.itu.int/ITU-R/…g=en
No indications of channel changes yet.
Where possible - where international clearance was already available for the new channel (due to it being a former analogue channel), or not required due to no interactions with other countries - the changes were implemented before DSO. Emley Moor is shown as having interactions with Ireland. Sutton Coldfield has no interactions listed so a swap of C49 to C39 could be made without affecting anyone else, even though we hadn't asked for it at Geneva 2006. Hannington BBC B could move from C51 to C39 because we had asked for C39, even though there was an interaction with France.
In the GE06 plan, we asked for channels 37, 39, 41, 44, 47, 48, 51 and 52 at Emley Moor, covering all previous analogue allocations, plus the new homes for ArqA and ArqB, all at 52.4 dBW = 173,780 W. C39 was presumably requested for the low-power HD service! It is now in use at Sheffield (the lower power there means it's still within Emley Moor's allocation, technically) in place of the original allocation of C49, to clear that for some other transmitter to use.
You can see that it's a complicated process with a bit of ebb and flow and negotiation required.
| link to this comment |
Briantist: In the diagram at the top of the page, you did say Emley Moor 48 to 50 and 51 to 39. Obviously this didn't happen! As you say, it's not now likely to happen unless moving Emley Moor is a pre-requisite for accommodating Waltham or another transmitter using C61 or C62.
For Waltham we asked for 29, 35, 54, 56, 57, 58, 61 and 64, and no international interactions are shown - which does suggest that implementation there is delayed until something else, which does interact, can be moved out of the way.
The mix of what's in and what's not in the plan is odd. Nottingham is in, Stanton Moor isn't, but they have the same power level. It's not that all pre-DSO digital transmitters are in, Idle isn't.
All references are to the GE06 plan as it stood in August 2006, I haven't gone through all the updates to figure out the current state!
| link to this comment |
mike Roberts: A number of propogation conditions can mean different frequencies travel more or less well. In general, the higher the frequency, the less it bends over terrain, so you would normally expect - from the wrong side of the Pennines - that the higher frequencies will be less strong than the lower ones. In addition, reflections - causing multiple paths from the transmitter to your aerial - interact differently with different wavelengths (the difference in path length is a different number of wavelengths at different frequencies) and therefore their effect on signal strength can cause changes through measurement.
The power levels as stated are envelope power limits, not absolute limits. In the worst case the different carriers making up the signal could all align the same way at one instant, or all different directions at another instant - the difference between these two conditions is potentially 76 dB! In practice the peak-to-mean ratio is clipped at 7-10 dB, but this is still enough for programme content to mean that different muxes with the same nominal maximum power output read at different levels (source: BBC RD - Publications - White Paper 156 DVB-T and Voltage Ratings of Transmission Equipment ).
Really, the box should measure the size of the pilot and TPS carriers, which do *not* change amplitude (though they do change phase), rather than the whole bandwidth, but that is the customary approach.
Finally, as Brian says, there may be differences in the radiation patterns. The radiation pattern of a full transmitting antenna is made up by combining many smaller elements. The UHF aerial for Emley Moor's second mast (this collapsed before the current tower was built) was eight tiers of 6 panels, each panel carrying 4 elements (8 *components* were fitted to each panel, but the active part was the vertical slot *between* the components, odd as that may sound). Again, the slots behave slightly differently at different frequencies - optimal resonance is achieved at 1/4 of the wavelength, so you can never tune the response of an aerial carrying more than one service perfectly for all of them. The overall radiation pattern is made up by the reinforcing and cancelling signals from each element on each panel.
That original antenna contained transformers to feed only 60% of the power into the two panels in each tier on the south-west face, compared to the other two faces. Pushing any more power into the Pennines was considered a waste. You can see the BBC's report on that antenna at BBC RD - Publications - R&D Report 1966-47 : UHF transmitting aerial for the Emley Moor Television Station , particularly how its radiation pattern differed at C44 (BBC One) and C51 (BBC Two).
Because the Emley Moor tower is now a listed building, the external appearance had to remain the same even while changing the antennas inside the fibreglass shrouds at the top of the mast. In turn, though, that meant that Arqiva didn't have to apply for planning permission to change the antennas as they had at most other sites. So we don't know anything about what the new aerial is like and what its radiation pattern might be.
| link to this comment |
Andy: Yes, impulse interference can be a problem. It can be reduced by swapping the aerial for a new one which has a balun, a device that matches the properties of the aerial better to the properties of the cable. Older aerials tended not to have a balun or other matching device.
Aerials meeting CAI Standards 1-4 (which require a balun or otherwise matching to the cable) are usually marketed as 'digital' aerials, though there's nothing inherently digital about them. The testing to actually get the CAI Standard label is quite expensive, so many perfectly good aerials meet the standard but don't get the label. If another aerial in the same family has the label, it's likely this one matches up, the manufacturer just only did the testing for
Log-periodic aerials are inherently balanced and therefore don't need a balun.
You can also improve the screening of the cable - traditional so-called 'low loss' coax cable is now considered anything but. For best results, a dense copper braid screen over copper foil is recommended. This is normally marketed as 'satellite grade'.
You might also try moving your aerial around a little so it no longer points at the road. Aerials have a reasonably wide angle of acceptance before losing a significant amount of gain, so a few degrees to one side or the other may resolve the problem.
| link to this comment |
Alan: Digital UK reckon the best transmitter for you, both now and after switchover, is Bilsdale West Moor. It's not that near Redcar; it's actually the other side of Middlesbrough.
Bilsdale transmits currently at 1.6 kW to 6 kW depending on the multiplex, compared to analogue at 500 kW. At switchover the digital signals will be 100 kW for PSB channels, 50 kW for COM channels. These levels are intended to give equivalent coverage compared to analogue for the COMs and slightly more for the PSBs.
The commercial multiplexes will be out of group after switchover, and you will need to change to a wideband or Group K aerial to get them. If you have *already* got a wideband, that might be the cause of some problems as they don't have a lot of gain at the lower frequencies currently used.
Results are currently expected to be variable on Mux 2 - carrying ITV1, ITV1 +1, ITV2, C4, C4+1, E4, More 4 and C5 - and Mux D, which carries Yesterday, ITV4, Film4 among others.
The Seaham transmitter will be 'Freeview Light', carrying only the public-service multiplexes: the BBC's channels, the ones I listed earlier for Mux 2, and the HD services BBC One HD, BBC HD, ITV1 HD and 4hd. By the time the Tyne Tees region has switched, BBC HD may have become BBC Two HD, and a fifth HD service may have joined the line-up.
| link to this comment |
C: Sky require a minimum £10 per month payment or they'll disable the recording functions on the boxes. It's quite difficult to find information about paying this fee, Sky would obviously prefer to extract the £20 basic subscription.
Ending your subscription also means you won't be able to time-shift, and you won't be able to play back anything you previously recorded either.
To get full recording features back without paying a subscription, you can buy a Freesat+ box as a drop-in replacement for the Sky box.
Channels that are broadcast without encryption don't require the viewing card, but some regional variants of ITV1, ITV1 +1, ITV1 HD and Channel 5 are encrypted - if you're in one of these regions, that channel will stop working if you remove the card. (Channel 5 has different advertising regions, the programmes are the same.) The region selection is based on the postcode that the viewing card was sent to. There are a couple of other channels that require a viewing card - see Compare Freesat and Freesat-from-Sky TV | ukfree.tv - independent free digital TV advice for the differences in the line-up.
| link to this comment |
andy: The Wokingham area suffers from there being a big difference between the analogue and digital signal levels from Hannington. This is a deliberate restriction on the digital output, to protect the analogue services at the Guildford transmitter, and means you can have completely clear analogue pictures and yet unreliable digital.
This flaw was designed into the plan in 1998 and was never lifted despite much investigation of the actual effects on Guildford reception around 2001/2. It will be lifted for the PSBs at switchover (8 and 22 February 2012) and for the commercial multiplexes after Guildford switches (4 and 18 April).
You may get better results from the Crystal Palace transmitter, now and after switchover.
I don't have an explanation why it should have got worse recently, unless a new antenna at Guildford has a different radiation pattern from before (causing an increase in interference) - I can't see any other transmitter that's recently switched over which clashes.
| link to this comment |
Howard: Can you confirm which transmitter you're using? If you're trying to use Hannington (aerial would point south-west), you may get better results from Crystal Palace both now and after switchover. The aerial would need to point east-ish for CP, and you'd probably need to replace it as an old aerial for Hannington would be Group E, designed to *reject* signals in the Group A range that Crystal Palace uses.
There are a couple of hills blocking line-of-sight from your aerial to Hannington, which is probably the cause of the problem.
It is worth checking that your box is tuned to the transmitter the aerial is pointing at - see Digital Region Overlap for advice on this.
| link to this comment |
mike Roberts: As FM radio is on a lower frequency, it bends more over terrain and so can travel further than UHF television.
The radiation patterns for radio transmitters *are* published by Ofcom, and you can see the one for Emley Moor at FM, MW and LW radio broadcasting | ukfree.tv - independent free digital TV advice . However, The Pulse broadcasts from Vicars Lot, a site several miles to the west and omnidirectional: Vicars Lot analogue radio transmitter | ukfree.tv - independent free digital TV advice .
| link to this comment |
Dave Lindsay: The antenna would have been designed to minimize the differences between channels, but it's an inevitable consequence of having multiple channels share one aerial, that the radiation pattern of each channel is a bit of a compromise.
The picture is somewhat exaggerated as engineers normally measure differences in decibels (dB) while those graphs are shown in relative volts. To convert, take the base-10 logarithm of the voltage ratio ('log' on most calculators, LOG10 in Excel) and multiply by 20.
Giving each channel its own antenna at the same site would still be a compromise, as the coverage area is also affected by the aerial's height. Each antenna could be shorter - fewer tiers - to reduce the differences in height, but that would reduce the gain of the aerial and increase the electrical power needed to produce the same output.
In the US, it seems to be common to erect a tower with quite a wide platform that the various antennas then are mounted on - where they do share sites at all. The Empire State Building is festooned with different aerials.
As it is, the commercial multiplexes at Emley Moor are on an aerial slightly further down the mast (about 11.5 metres) than the PSB multiplexes, presumably so that each can be optimized better for the frequencies it's carrying, though it will also offer greater redundancy. The other issue is that the commercial muxes clash more with transmissions from other sites (e.g. Nottingham also uses 48/51/52) and with PSB transmissions from the relay transmitters - both co-channel, using the same channel at both sites, and adjacent-channel interference, due to the imperfect nature of the transmitter - some power leaks into adjacent channels. It is filtered, but filters with a less sharp roll-off are permitted at lower-power sites, therefore more leakage. This only affects the residents near to that site, but it still ends up reducing coverage.
There's a possibility that Emley Moor ArqB might currently be restricted to half power to avoid damage to the low-power Mux 1 at Pontop Pike - there is provision for that in Ofcom's licence documents.
Signal propogation is slightly frequency-dependent, and higher frequencies don't travel quite as well as lower ones, nor carry along cables quite as well. I also mentioned multi-path effects before.
All this put together means you may see different levels across the various multiplexes, and those differences may change over time, despite the published maximum ERPs being identical.
| link to this comment |
Mazbar: Channel moves have to be negotiated with neighbouring countries, for the highest-output transmitters. The Geneva 2006 frequency plan for Europe, Africa and the Middle East shows an interaction with Ireland, for Winter Hill.
I'd guess that they will be moved to C49 and C50, on the basis that those channels have been cleared from the Sutton Coldfield and Emley Moor plans. These are still in Group C/D. If those aren't possible, I'm sure great efforts will be taken to keep in Group C/D if at all possible, as Winter Hill has the second-largest population coverage in the country, after Crystal Palace, and just beating Sutton Coldfield.
However, the plans for C31 to C37 are still not finalized; Arqiva have been asked to provide Reference Offers for Network Access for up to three new multiplexes in this space. A wideband aerial would be needed for best results on these frequencies. A Group E might be good enough down at C31, which I see is a possible allocation at Winter Hill. International clearance would also be required for these channels, though, so don't treat those as definite allocations.
| link to this comment |
Kate: Ofcom regulates the charges that Sky can charge other providers to carry their sports and movie channels (wholesale charges). It does not regulate the charges that Sky is making for carrying channels in their EPG. That's why we're in this mess.
Encryption is a slightly complicated subject. Encryption can be used for two reasons:
1. To gain access to direct subscription revenue
2. To avoid rights issues that would involve paying more for programmes
The footprints of the earliest satellites in the cluster that carry the UK channels actually cover most of western Europe. You can see them at
ASTRA 2A - SES.com
and
ASTRA 2B - SES.com
(the pages are currently broken, hopefully they'll be back soon). The programme-makers - particularly films and acquisitions from the US - want more money if the broadcasts can be received anywhere in Europe. Encryption segregates the market, only allowing those with a UK viewing card to watch a channel intended for the UK, avoiding this problem.
Astra, with influence from the BBC, launched a new satellite Astra 2D in 2000 with a footprint only covering the UK and Ireland. This allowed the BBC to stop paying Sky to encrypt their channels and broadcast free-to-air. The EXACT SAME UNENCRYPTED transmissions are viewed by Freesat, Sky, and non-branded free-to-air boxes. There is NO encrypted copy of BBC One, Two, Three or Four on this satellite cluster. Later, Channel 4 moved all of their non-subscription channels here and ITV moved most of theirs, and there's also one version of Channel 5. Unfortunately, it's run out of capacity, so the other channels cannot move yet.
Even if you do encrypt, you may not get any revenue. There are 'free-to-view' channels such as 5* and 5 USA, where the operator has decided that ANY current or former Sky subscriber can watch the channel. It's encrypted, and you need a current-generation viewing card and a Sky box (because Sky's encryption method is proprietary), but you don't need an ongoing subscription. Sky call these 'Included Channels' on their website and indicate those that require the viewing card.
Of the traditional PSB channels, only a few regional variants of ITV1 and Channel 5 are encrypted, and those are 'included channels'.
On another page, Briantist claimed that transponder rental is about £4m per year. One transponder carries seven to nine SD channels or variants, or three to four HD channels, or of course a mixture, but on average maybe £500k for an SD channel. That said, there are 18 SD variants of BBC One, £9m.
Sky charge the BBC £5.6m for BBC One being on the platform at all, £25,000 for the EPG slot, and a very complicated charge I haven't fully worked out for regionalization, could be as much as £500k. But that is on top of the broadcasting charges that have already been incurred, for ZERO additional work on Sky's part.
| link to this comment |
I should add that there is a new satellite, Astra 1N, designed to provide more capacity for the UK and Ireland channels. One of its broadcast dishes has a footprint covering only the British Isles. It should have arrived at the cluster site in the last day or so, or if it hasn't, it will do soon. The rumour is that some of the 'free-to-view' channels will move across and become free-to-air, no encryption.
Channel 4 HD recently stopped using encryption and moved to the Eurobird 1 satellite which is a little further away, but still close enough to provide coverage. This is Europe-wide. They have decided it's better to pay the extra for content than to continue to pay for encryption. It may well move to Astra 1N once that goes into service, as Channel 4 have agreed to rent space on that satellite.
| link to this comment |
Channel 5 have definitely applied. For some inexplicable reason Ofcom's web team have put the application under the Third Invitation to Apply section, rather than creating a top-level Applications Received (Third ITA) section as for the previous two openings.
Ofcom | Third Statutory Notice of Invitation to Apply for DTT Multiplex B Capacity
As expected this is a simulcast of Channel 5 in HD.
| link to this comment |
Dave Lindsay: It's helpful to cross-reference with Arqiva's Reference Offer for Network Access from 2005.
Useful documentation
Emley Moor was originally an IBA transmitter so you'll find it under the Arqiva offer, rather than the ex-NGW (former BBC transmitters).
If you look at Appendix 3, List of Main Stations, you'll see that they intended to construct one antenna for the PSBs, and one for the COMs. The reserve antenna can act for the PSBs or for the COMs but not both at once.
My belief is that the two main antennas, PSB and COM, simply sit on top of one another with the PSBs on top, giving the appearance of forming a single antenna. The difference of 11.5 metres is the distance between the centre points of the two antennas (Ofcom use average height). Each antenna is constructed in halves to allow half-antenna running. Each panel is 1.09m in height - if they're using Radio Freqency Solutions' PHP panels - which would suggest 10 tiers, five tiers in each half antenna.
Sandy Heath's data is odd - Ofcom are listing SDN at the same height as the PSB muxes, which doesn't sound right (and the difference between the two is only 2.7m). It would certainly make sense to put 48/51/52 on a different antenna from 21/24/27. Arqiva did project a Class 2 antenna system, each antenna able to offer half-working (at 6 dB down) so I assume that the top 6 tiers are one antenna for PSBs (in 2 x 3 tiers) and the bottom 6 for the COMs.
The reason I say we don't know exactly what's in there is that at other sites, e.g. Winter Hill, the main antenna is a wrap-around of the main lattice structure - I assume RFS PHP12S which have 12 panels per tier - and at others, e.g. Hannington and Dover, the structure has five faces, e.g. RFS PHP5S. At Dover, only three of the five faces have panels fitted, to reduce the amount of power sent into France.
| link to this comment |
Briantist: The DTT Allocation Committee could still decide not to allocate any capacity this time around, but I think they'd have to have a very good reason for doing so.
This time, Channel 5 are offering a 24-hour simulcast of the Channel 5 Qualifying Service, although they do say "we wish to reserve the option of exploring possible ways for other providers to make use of some of the day time and late night hours". This was the sticking point last time, that they had said that 6am to 5pm would be an HD service provided by another broadcaster, without stating who that would be.
Of course, last time around, Five was still owned by RTL who were trying to get rid of it, while it's now owned by Richard Desmond's Northern and Shell.
| link to this comment |
Dean: Make sure you do a factory reset to clear out all existing stored channels. Your equipment could get confused with ArqB moving to C52 and ArqA replacing it on C67.
C52 has never before been used by the Mendip transmitter, so you need to check all legacy devices like VCRs to ensure that they're not outputting on a clashing channel. Clashes are possible on C52 itself, C51, C53 (due to inadequate filtering), and five or nine channels below, so C43 or C47 - though I would have expected more problems.
The power level is *very* slightly lower on C52 for the moment than it was on C67, but the much lower frequency should result in overall more signal being received for this multiplex. SDN having gone to full power on C48 means that the overall signal level is a lot higher, which could result in too much signal.
Just to confuse things further, the configuration of ArqB will be changed on 8 November - it's not clear whether this is to increase capacity or increase coverage. For you the result is a slightly lower probability of reliable reception, but it's still predicted to be a 98% chance.
Siston is a 'Freeview Light' transmitter and only provides the three PSB multiplexes.
| link to this comment |
Nick: Money, and the design of the original licences to broadcast. See Will there ever be more services on the Freeview Light transmitters? | ukfree.tv - independent free digital TV advice for more.
The main transmitter they're using is probably Darvel. If you provide a full postcode we can check whether a full service is expected to be available from this or any other full-service transmitter.
| link to this comment |
Briantist: I'd dispute that MPEG Audio Layer 2 audio is better than NICAM 728. Equivalent, possibly, at 256 kbps (the rate the BBC use) but not at 128 kbps as many of the commercial channels use.
Legacy mono audio was FM with a permitted deviation of plus/minus 50 kHz.
Freeview HD audio is AAC-LC (low complexity MPEG-4 Advanced Audio Codec) and I don't know what the bitrate is. Ofcom guessed, for the Second Invitation To Apply, that 192-384 kbps would be used, but bear in mind that this is for 5.1 audio rather than stereo. AAC is generally considered to require half the bitrate of MP3 for the same quality, and MP3 (MPEG-1 Audio Layer 3) itself substantially less than Layer 2.
The *volume* of the audio is nothing to do with it. Layer 2 and AAC can handle the same dynamic range. Indeed they work by hiding noise caused by low dynamic range - caused by saving bits - behind loud sounds. A loud sound at one frequency means that whole sub-band can be encoded with fewer bits.
As I understand it, differences in volume are generally caused by the downmix of 5.1 audio for stereo output. The audio stream carries metadata to tell the receiver what parts of which channel to combine to produce an output only for the front speakers. The crude version is of course to just take the front-left and front-right channels, omitting the contribution from rear-left, rear-right, front-centre and bass channels.
| link to this comment |
jgked: Because the wallplates are rubbish? See Satellite, Television, FM, DAB, Aerial, Coaxial Cable, Plugs, Sockets, Connectors & Leads for one installer's opinion on using them and the sort that should be used, if you're going to.
Predicted reception from Wenvoe is already poor, probably due to interference on 42/45/49 from a nearby relay transmitter, and additional signal loss of the wallplate, or noise pick-up, could well push some channels into being too noisy to decode.
| link to this comment |
Nicholas Wilmott: It's a '1'-series because its final intended service position is 19.2°E. It's only filling in at 28.2°E until the proper replacements, 2E, 2F and 2G, are built and launched over the next few years.
There is nothing analogue or digital about the satellites, they just relay whatever is transmitted up to them from the ground. The first digital tests at 28.2°E were from Astra 1D, moved there at the end of its service life for that purpose. Astra 1 satellites at 19.2°E (and 2C, which has had a history of being moved here there and everywhere) now carry a mix of analogue channels and digital multiplexes on the various transponders. The remaining analogue channels have been told to move to digital before being shut down next year.
As I said, 2C is at 19.2°E, and could presumably have been moved back to 28.2°E if it was still suitable. However, that only has a single pan-European beam, and the demand is for UK-only footprint. Presumably the UK spot beam got added some time in Astra 1N's construction, too late to push up 2E to an earlier launch.
We still don't know how many of 1N's transponders can use UK-only footprint. In frequency terms, several of the transponders would overlap with Eurobird 1 (28.5°E, close enough to effectively be part of the Sky and Freesat platforms) or with 2A or 2B.
| link to this comment |
Gordon Davies: Make sure you're connecting the box to the TV with a digital link, such as HDMI, ONLY. If you connect SCART as well, the TV will often switch to the SCART input due to the box sending the Select signal. SCART is only SD.
| link to this comment |
David: An aerial isn't specifically 'analogue' or 'digital', just designed for part or all of the UHF band, though there were some things not often done on cheaper aerials that are recommended for most reliable digital reception.
For HD reception on Freeview, you need a Freeview HD-labelled set-top box, PVR or TV. A PVR is typically required to record, although there are a few TVs you can now plug a USB hard disk into to record. Humax's 'set-top box' HD-FOX-T2 can also be turned into a one-tuner recorder by plugging in a hard disk.
For satellite, you can cancel your subscription to Sky and just use the Sky+ box to receive free-to-air and free-to-view channels. However, Sky will disable the recording and time-shifting functions. You also can't even watch things you previously recorded.
To get recording and timeshift features back, you can get a Freesat+HD PVR. You don't need an additional set-top box. You just plug it in in place of the Sky+ box.
If you're currently distributing the output of the Sky box to the bedrooms, you will also need a plug-in RF modulator as I'm not aware of any Freesat boxes that have one. As an alternative, you should consider getting an additional cable run from the dish to the bedrooms and put a Freesat box in there as well, allowing a viewer in the bedroom to watch something different from the main TV.
You can compare the channels available through a non-subscription Sky+ box ('Freesat-from-Sky'), switching to Freesat, or switching to Freeview, at Compare Freeview and Freesat TV | ukfree.tv - independent free digital TV advice .
If you provide a full postcode we can see whether an aerial change might be necessary to get all channels on Freeview.
| link to this comment |
Coupland: Yes, these boxes only supported 2K mode and after switchover, all transmissions (except HD) are in 8K mode.
8K mode was always in the spec, the BBC were particularly keen on it as it allows larger single-frequency networks, but it requires more memory in the earliest stages of decoding so it was cheaper to make a box without it.
onDigital changed to be ITV Digital in 2001, and went into administration in 2002. So the box has to be at least nine years old.
| link to this comment |
Duncan Brack: Freesat tuners need an independent connection from the dish to the box. That's because the tuner has to send some control signals back up the cable to the dish, to select low or high frequency range and horizontal or vertical polarization. To cram in more channels, both polarizations are used for different services.
Freesat PVRs usually have two tuners, so you can record one programme while watching another. That requires two connections to the dish. Since the TV itself supports Freesat, you could connect only one of the PVR's inputs if you're short of connections.
| link to this comment |
Briantist: Audio description is a secondary mono stream that starts and stops as required. That's true of SD services as well as HD services. For HD, audio description is encoded as HE-AAC - the requirement to use AAC-LC for the main audio stream is that chipsets generally can handle two different streams of AAC at the same time, they can't handle one AAC and one Dolby.
In Ofcom's Second Invitation to Apply, they included a 'Timing of the Fourth HD Service' document:
http://stakeholders.ofcom….pdf
which states (section 3.9) that 32 kbps would be allocated for audio description, in addition to the 192-384 kbps for the main multi-channel audio.
This was obviously before the service launched, so estimates were necessary. The 'Timing of the fifth HD service' document is very thin in comparison, because they're just saying 'the BBC said it was OK'.
| link to this comment |
Briantist: Changing the guard interval would not itself improve reception directly (except in rare cases of strong distant echoes, which are unlikely; 7.5km is plenty of distance to prevent this problem). It would improve only if the intent was to synchronize transmissions with another transmitter, in which case the overlap area would have constructive, rather than destructive, interference. It all hinges on the timing.
The nearest candidate using the same frequencies will be Chatton, when it switches over at the end of next year. For that reason, I doubt that it is to do with improving coverage.
Others are certainly reporting that the guard interval has not changed and therefore capacity has increased. The larger capacity is for the moment just carrying more null packets.
On its own, this change will reduce coverage slightly.
The retrofit is due to complete, at least for ArqB, on 23 November (Selkirk, and Tacolneston DSO 2), so we should know more then.
| link to this comment |
Andrew Tegala: To be honest I'm surprised they're using Hannington at all. Slough was always considered part of the London TV region, and Hannington has restricted digital coverage to the east at present. Are there any trees or buildings in the direction of the Crystal Palace transmitter that could be blocking reception?
It is possible to combine the signals from two aerials, one pointing in each direction, but obviously that requires extra outlay.
If the system is channelised, it will currently be handling 11 frequencies (5 analogue, six digital) so there will be some spare slots on it after switchover. You only really need the three PSB multiplexes from the other transmitter, the channels on the SDN, ArqA and ArqB multiplexes are all the same throughout England.
Do a survey of your neighbours, see which service they'd prefer and if they'd be interested in receiving both. The management agent will want to recover the cost somehow, of course.
If the aerial was changed, everyone would lose reception until they retuned, so it would have to be co-ordinated carefully.
You should first check that it's not a problem of too much signal on the Crystal Palace services. What do you get on analogue? What does your Freeview box say if you try to manually tune in on C22 and C25? If the signal strength is higher than for Hannington services but quality is lower, it's likely that the signal level is actually too high - this could be considered a fault on the system.
| link to this comment |
Tim: That booster? You probably don't need it.
Check that the box has actually tuned to Black Hill transmissions and not something else. The Kilmacolm relay transmitter is very close to you and uses lower frequencies, so could well be picked up when tuning, as older boxes often just store the first signal found when scanning. See Digital Region Overlap for thoughts on how to deal with reception from more than one transmitter.
Otherwise I'd be inclined to assume it's impulse interference caused by the thermostat or other central heating device (pump motor). Does it happen shortly after the central heating comes on?
If none of that sorts it, you can report the problem to the BBC at BBC - Reception problems . Select 'No' for 'Does this answer your problem?' and continue through.
Digital UK, and that BBC page, suggest that you can get a signal from the Strathyre Link transmitter, but I think that's very unlikely. It's probably what you'd expect to get from Black Hill if your aerial was pointing at Strathyre Link. My guess it's treated as a Single Frequency Network in the DUK predictor, but the sole purpose of Strathyre Link is to get the signal down the valley to the Strathyre transmitter itself, and hence is very, very low power (130 milliwatts).
| link to this comment |
Tracey: The aerial might be pointing to the Heyshaw relay. This 'Freeview Light' transmitter only provides the channels you've mentioned.
You should be able to get a full service from Bilsdale - both now and after switchover. The chance of a full service from Emley Moor is slightly lower at the moment - the ArqB multiplex clashes with Multiplex 1 at the Pontop Pike transmitter that serves Newcastle. Belmont is also strong enough for a good service on the SDN multiplex as well as the public-service multiplexes.
For Heyshaw, the aerial would be aligned vertically - elements going up-and-down - and pointing west-north-west (291° on a compass). For Bilsdale, Emley Moor or Belmont it would need to be horizontally-polarized - elements going side-to-side. Bilsdale is roughly north-east (32°), Emley Moor to the south (190°), and Belmont south-east (129°).
You, or future tenants, might well be more interested in West Yorkshire news than Tyne Tees, so I'd recommend Emley Moor even though it might be a bit harder to get reliable results from there than from Bilsdale. It's likely that the aerial would have to be replaced, not just moved and rotated, but the cost of an aerial installation is mostly the labour cost anyway.
| link to this comment |
Iain: The licensed combinations for ITV1 HD on satellite are:
Central
Granada + Border
London
Meridian + Anglia
Wales + West (+ Westcountry)
Yorkshire + Tyne Tees
That matches the ITV1 +1 regions licensed on satellite and Freeview. They also match ITV1's macro advertising regions. ITV are more interested in getting you the right ads than the right programmes.
However, so far, only Central, London, Granada, and Meridian/Anglia have launched on satellite and Freeview.
To get started quickly, I believe all 'early' Freeview HD services carried London, but they're switching to their own services as switchover happens. You might find that Yorkshire Tyne Tees (Emley Moor news) starts once the London region has switched over in April.
ITV might invest in more variants - including launching the two that they have licences for already - now that more capacity is available on the Astra 1N satellite.
| link to this comment |
Ofcom's Table of Digital Stations version 6 has this relay replaced with 'Sunningdale', at the same power and height. This is the name of another building nearby, on Chapelhill Road CH46 9RG.
Wirral Metropolitan Borough Council were notified in May 2010 that the building carrying the Bidston relay was to be demolished: DEM/10/00628 at Wirral Metropolitan Borough Council Planning Pages
| link to this comment |
Briantist: Reviewing the older documents, as the NGR in v5 doesn't match this grid reference, the grid reference, height and power were altered in version 5 of the document; only the name was changed in v6 (and the NGR was slightly altered).
New height is 55.3m, 4.8m higher than before, and the new power level is 30W, up from 25W.
| link to this comment |
Alan: Signal strength should never hit 100%. You have too much signal already. If you have a booster, get rid of it. You will probably need to add attenuators to get back into range - or just replace the old perfectly good aerial.
| link to this comment |
Bob Loader: With a prediction of 100% chance of reliable reception, chances are that you have too much signal. See Freeview signals: too much of a good thing is bad for you | ukfree.tv - independent free digital TV advice .
Another possibility is that your box has decided to tune in the signals from The Wrekin, which also have a predicted 100% chance across the board, as they are on lower frequencies. See Digital Region Overlap for how to resolve this issue.
| link to this comment |
Graham: It's quite likely that your box has tuned in ArqB from Sutton Coldfield, on C39, rather than from The Wrekin on C47. See Digital Region Overlap.
I'd second the other suggestions to remove the amplifier. It shouldn't be necessary.
| link to this comment |
george: Depends on the box.
Sky boxes will retune automatically whenever Sky change the EPG data. You may need a current viewing card inserted to get the right region, if and when ITV move some ITV1 regions.
Freesat-branded boxes are supposed to retune automatically, but not all do. Some need to be put in standby to do it, or you have to select a retune function. Some viewers found they had to do a factory reset when BBC HD and BBC One HD changed over to DVB-S2 on the same transponder.
Generic free-to-air receivers will need to be retuned manually. Don't do it until the channels disappear from their old location.
The Astra 1N satellite is in the cluster of satellites at 28.2°E. You don't have to move your dish at all.
| link to this comment |
Nedbod: The compression will be increased to make space.
trevorjharris: The bit rate will be reduced but the BBC and the other broadcasters are happy that, with improved MPEG-4 AVC encoders, picture quality will not be.
The specification provides a toolbox for how content could be encoded, and information on how to decode it. The difficulty is all in the encoder, how it is able to process the content to most efficiently reduce the redundant data, under near-real-time constraints. Early AVC encoders were basically MPEG-2 encoders not using any of the new tools, just using a few ways of packaging the resulting stream slightly more efficiently.
| link to this comment |
NottsUK: My assumption is that everything is still in test, with experimentation on just how much or little forward-error-correction is required, and how reliable use of 8PSK will be. 8-phase-shift keying, as opposed to quadrature phase-shift keying (QPSK), delivers three bits per symbol rather than two, but requires more signal-to-noise ratio for the same error-correcting code rate.
DVB-S2 also defines 16-APSK and 32-APSK, which require multiple amplitudes as well as changing the phase, but I wouldn't expect to see support in domestic receivers, as it's not mandatory.
I'll consider testing ended when a service is deleted from a 2A/2B/2D transponder, or an FTA service appears in the Freesat EPG.
| link to this comment |
mrdtv: Depends who you believe. Considering I was getting the same readings percentage-wise on the digital tests as for analogue signals, I'd say it was full power, though of course the digital box isn't designed to measure an analogue signal.
If I'm right about the calibration of my box's strength meter, my usual level for low-power digital at 35% translates to 56 dBuV, while the high-power test at 60% translates to 71 dBuV, or 15 dB higher than current values. The increase at DSO is only supposed to be 10 dB. 15 dB would be near 600 kW.
BBC Two analogue was on noticeably lower power (showing only 40% on C33 on my PVR, though again measured as if it were a digital signal), which was attributed to it running from the back-up transmitter at Croydon.
| link to this comment |
Perhaps this is the reason for the increase in capacity on ArqB. Or it could be on ArqA, as I believe the last switched-over transmitter still running Mux C is Sandy Heath, and that will change over to 64QAM 2/3 on 23 November, on its final channel and power level, according to Digital UK's postcode checker.
Either of those options would require a sub-lease from the BBC's pre-DSO Mux B capacity for the regions yet to switch (no chance they launch without London!)
Another alternative is that G.O.L.D. will get kicked off Mux A, as Top-Up TV is ulimately only borrowing Channel 5's capacity, as I understand it. TUTV aren't currently promoting G.O.L.D. as part of their subscriptions.
Channel 5 +1 is very unlikely to join the main channel on Mux 2/D3&4. The precedent is that timeshifts are not treated as qualifying services. Channel 4 +1 and all the regional ITV1 +1s are licenced under Digital Television Programme Service licences. That means that even if ITV and Channel 4 had capacity, they would have to ask Ofcom's permission to carry C5+1. ITV plc lost a slot to allow Channel 5 on in the first place; there is about one slot of spare capacity if Ofcom would get their backsides in gear and kick the remnants of Teletext off the mux, but you'd have to assume that would revert to ITV.
Of course C5 do have a regional advertising structure, which could complicate things.
| link to this comment |
jb38: Caldbeck COM muxes are on low power until 24 October 2012, to reduce interference to the low-power digital services at Divis (Mux 1, A and B). Divis completes switchover on 24/10/2012.
Bill: You might be using a Freeview Light transmitter such as Kirkby Stephen - in which case replacing the aerial with a good quality Group A design, horizontally polarized and pointed at Caldbeck, may still produce good results. We need a full postcode to give a better answer.
| link to this comment |
Briantist: I've recently been using BCL easyConverter Desktop BCL easyConverter Desktop — PDF to Word Converter — Accurate PDF Converter. to attack Ofcom's PDF files. It says it's PDF-to-Word but it's actually PDF-to-RTF.
I used that, along with Word's Compare Documents feature, to spot the change from Bidston to Sunningdale.
| link to this comment |
Peter Henderson: Internationally-cleared frequencies are published in the Geneva 2006 broadcasting plan, and updates to it. The Newcastle site was cleared for 12B, the BBC national ensemble, in May 2009, and Camlough in July 2009. Camlough shows definite agreement from Ireland (and Belgium, France and Holland, since it will contribute to the overall power transmitted by the whole SFN); Newcastle doesn't, but it also doesn't show the countries expected to be affected. No-one appears to have raised a complaint, though.
http://www.itu.int/ITU-R/…g=en is updated every two weeks, though GE06 plans, covering VHF Band III for T-DAB and UHF Bands IV and V for DVB-T, are not updated every time.
In the Reserved Assignments List at Ofcom | DAB Technical Policy Documents , Camlough and Newcastle are both listed as having 'other possible local block usage' on 10C and 12D. 12D is the Northern Ireland local multiplex carrying BBC Ulster. I can't find a reference to use of 10C in Northern Ireland anywhere else, though.
| link to this comment |
mike: Did you have digital TV before switchover? If not, you may still have a Group A aerial. For all channels from the Sandy Heath transmitter, you will probably need to change to a wideband type.
The signal levels are expected to be sufficient even with the SDN and ArqA multiplexes still on low power. ArqA will go to its final location and power level on 23 November after Tacolneston finishes switchover on that date.
If you had reliable digital reception before switchover, you should already have a wideband aerial. I'd then suspect too much signal - see Freeview signals: too much of a good thing is bad for you | ukfree.tv - independent free digital TV advice for more information.
| link to this comment |
Brian: Contact your landlord or management agent. The signal levels are expected to be sufficient for a very good chance of reliable reception at that postcode, which means that probably there's too much loss in the building's distribution cabling.
They will have to be prepared to recalibrate and possibly retune the system at switchover anyway, depending on how it's constructed.
| link to this comment |
Briantist: You could use something like Gravatar instead: Gravatar - Globally Recognized Avatars . I admit my identicon is pretty boring, just a few purple triangles in the corners.
| link to this comment |
Bruce Dorward: It could also simply be a fault at the Border news studio meaning that they couldn't actually put the programme out. If this happens ITV normally will find a different region. Having said that, the programme is online at
Full Programme Repeat | Border (ITV Lookaround) - ITV Local
.
If you were watching ITV1 +1 you would expect to get Granada, as ITV have only got enough time-delay equipment and monitoring for six services - the licence for your region is for 'ITV1 +1 Granada Border', and the content comes from Granada as that serves several million more people than Border does. They only have room for six time-shift services on satellite, which may explain the limitation on Freeview.
I believe Border is also low on the list of regions to get an HD upgrade, and you should expect to get Granada news on ITV1 HD (logical channel number 51) until the rollout is complete. It may also be up to the BBC to sort out enough versions of the HD multiplex to carry it.
| link to this comment |
Rich: Many of the North Norfolk relays exist only to provide the 'correct' local news to viewers otherwise covered perfectly well by the Belmont main transmitter in Lincolnshire. If you provide a full postcode we can check whether this is possible.
The transmitter sites, masts and aerials are owned by Arqiva but they are simply contracted to transmit the six licensed multiplexes. The commercial multiplexes are SDN (owned by ITV plc) and ArqA and ArqB, owned by a different division of Arqiva. In turn they're operating on a commercial basis and would have to increase their prices a lot to cover the increased costs of transmission. It's expected to be about a 70% increase in costs to transmit from all relays, even if frequencies could be found, which they probably couldn't.
Digital UK know the answer to that question, as an organization, but I'd expect it wasn't in the call centre's script.
| link to this comment |
tony: First, make sure you do a full retune - also called first-time installation, full reset, factory reset, virgin mode, default setting. It may be under the Software Update menu rather than under Installation or Tuning. Some boxes won't store channels that they think they already know about, you have to clear the existing channel list. You'll need to do this again on the 23rd.
Check whether your box is on the list of equipment that is known not to work with 8K mode - http://www.digitaluk.co.u…ment . If you haven't retuned for a long time it could also have a problem with a larger Network Information Table - see http://www.digitaluk.co.u…tnit .
There are also some boxes which have a bug meaning they can't pick up transmissions in 8K mode when there is a negative frequency offset. The box will say 'T810' on its sticker somewhere. See Unofficial Vestel PVR Information (UK) - T810 Freeview Recorder and Unofficial Vestel PVR Information (UK) - Digital Switchover for more information on those.
Assuming you didn't have any trouble with BBC Two analogue before switchover, it's unlikely to be single-frequency interference. It could be that the total signal level received is now too large, though, now that the new Great Yarmouth transmitter has started up.
If the BBC channels are stored - after doing the full reset - but are too weak to actually use, your box may have tuned into Great Yarmouth rather than Tacolneston. There may be a working set up at 800 or so in the channel list. In that case, see Digital Region Overlap for thoughts on how to sort this out.
| link to this comment |
Bill: Yes, the Ravenstonedale transmitter is 'Freeview Light', it only carries the three public service multiplexes, so you wouldn't expect to get Dave or Yesterday.
The predictor shows a poor chance of getting reliable reception of the commercial muxes from Caldbeck. The PSB muxes offer a good chance of reliable reception. You could try it, but you might need to have a particularly large aerial installation.
If you do this, Digital UK show that your reception of the commercial multiplexes from Caldbeck will get worse after the Bilsdale transmitter switches over next September, for about a month before Divis (Northern Ireland) switches over. Once that's done, Caldbeck's commercial muxes can go up to their full output power, restoring roughly the same (still poor) prediction.
It may be easier to go with satellite, although Dave and Yesterday are both Sky-exclusive subscription channels at present.
| link to this comment |
gordon: No further power increases are planned. The COM multiplexes are intended to be half the power of the PSBs - they are not required to equal the PSB coverage.
| link to this comment |
Alex: This TV is on Digital UK's list of equipment that has a problem with the larger Network Information Table - http://www.digitaluk.co.u…tnit . That document provides a phone number to contact Sony.
Other posts on forums suggest that you should be doing a retune by pressing a '?' button, which may be on the TV itself.
There is a manual retune guide at http://www.digitaluk.co.u….pdf .
| link to this comment |
billy: The overall multiplex bitrate of BBC A is higher than Mux 1 was, but the BBC are required to clear Mux B for HD. They have to cram the services from Mux B - BBC Four/CBeebies, BBC Parliament, and the national radio stations - onto BBC A as well as those that were previously on Mux 1.
For the next two weeks, those services are still carried on Mux B as well as their new home on BBC A, so may appear twice in your channel list.
Overall, the bitrates for each service are expected to be about the same as before switchover, or a little less. CBeebies/BBC Four usually runs about 4 Mbit/s, BBC Parliament about 1.5 Mbit/s, and the radio stations something like 1.5 Mbit/s.
| link to this comment |
lm: I'd still argue that it's a communal facility provided for the tenants by the building management, and some part of your rent or building management fees should be going towards its upkeep. See PARAS - Professional Aerial Riggers Against The Sharks for thoughts on who to speak to and what to say.
You certainly shouldn't expect to pay for this yourself.
| link to this comment |
Alex: As I understand it, manufacturers can put their updates into a queue managed by the Digital TV Group's Testing group - Book an over-air download | DTG Testing .
I would expect the protocol to be DVB-SSU - DVB standards can be found at DVB - Digital Video Broadcasting - Standards & BlueBooks .
| link to this comment |
Clive Windy: Transmissions can travel a very long way, sometimes - under particular weather conditions - far further than planned. You can still get enough signal to detect even if it's not usable. I suspect the transmission on C52 is Emley Moor near Huddersfield.
Your mother's box must be one of those that simply stores the first version found rather than the best quality or strongest. See Digital Region Overlap for ideas on how to handle this.
| link to this comment |
Matt: The prediction for Mux 1 at your postcode is variable - only 4% of locations within your grid square are predicted to get reliable reception. This may be because the Heathfield transmitter uses C34 for Mux 1, although that is fairly low power. Crystal Palace also uses C34 for Mux C, at the same power level as Rowridge.
It's shown as 'variable' rather than 'poor' as there's a very good chance of getting reception 50% of the time. It will depend on weather conditions whether it works at any given time.
Switchover at Rowridge starts on 7 March 2012. Until then, there really isn't anything much you can do. A slight adjustment in the aerial's position, moving it slightly clockwise or anti-clockwise, might change the level of interference. It might have been aimed a bit north of Rowridge to improve reception of analogue Channel 5 from Fawley (which was turned off two years ago to facilitate Rowridge's retune, in turn to free up channels for the south west region's switchover).
The commercial multiplexes will remain on low power on their current channels from 21 March to 18 April 2012, as the final channel allocations clash with low-power services at Crystal Palace until that date. You will need to retune again on 18 April. If, after the retune, you find that the commercial multiplexes are unreliable, it may be worth re-orienting the aerial for vertical polarization.
| link to this comment |
billy: The symptoms you see are indeed the same as too little signal. The distorted signal pulls the 'value' of each carrier away from the value it should have, so it's interpreted incorrectly. Some carriers will not be disturbed enough to be misinterpreted, so error correction may be able to determine what most of the missing bits are, and reconstruct a block for the video and audio decoders to display it or play it back. Break-up happens when a block is detected to be uncorrectable or if the decoder runs out of valid data to play back (data is buffered, stored temporarily in memory; problems occur when the buffer runs empty). If the error rate is too severe, then the data which tells the receiver what channels are contained in this multiplex can't be decoded, and the receiver won't store it. In the most severe cases, the special Transmission Parameter Signalling carriers - which use a very robust scheme, transmitted redundantly, to indicate how the rest of the carriers are encoded - can't be decoded and the box won't even know the transmission is there.
There's really no way to tell whether it's too much signal without just trying to reduce the level and see what happens. Try disconnecting the aerial cable. If it works, you have grossly too much signal. If not, try an unamplified indoor aerial. Again, if it starts to work, too much signal. If you have a booster, take that out and see what happens. Amplified splitter in the loft or masthead amp? Bypass it, check the result on one TV.
Even if you have a signal strength meter, it may not be reliable. Each box seems to be calibrated differently. I strongly suspect that some have been calibrated to maximum possible input on one channel, but the distortion is caused by the SUM of all signals being too high, so you have to stay substantially below the maximum limit for 'safe' operation. I've seen reports that some boxes will report low signal levels when the levels are in fact high - my assumption there being that the box responds to not being able to decode by turning up the automatic gain control, and it's actually reporting the gain control level as the signal strength.
I usually look at Digital UK's postcode checker and make a guess. If they're shown as being within a short distance of a main transmitter and/or the prediction is 99-100% across the board, I usually assume too much signal :)
There are actually very few places in the country where you can have too little signal. Generally the problem is too much interference - the frequencies are very heavily reused across the country. It doesn't matter how much you amplify the signal, you amplify the interference just as much, and you add some extra noise from the amplifier itself. Amplification is only useful to offset losses along a cable, or occasionally if you have a very noisy receiver - see Usage and abusage of DTT TV booster amplifiers for how to use boosters correctly.
| link to this comment |
lisa: It's very hard to say that you're 'on' Sudbury or Rouncefall, both have quite a large area of influence and the overlap area is large. If you do get ArqB on C50 now - the channels that Dave listed - you will lose them on Wednesday and will have to retune to get them back. If you don't get them now, you *might* get them by retuning on Wednesday. However, it remains on lower power, so you're still not predicted to get them (if you're still at the address you were before).
| link to this comment |
lisa: As for *why* it's moving frequency: it's to give up C50 for Tacolneston to use from next week. The planned final home for this multiplex is C56, but this can't be used yet because Dover is still using it. There is another retune on 27 June 2012, the same day as stage 2 of Dover's switchover, when Sudbury's commercial multiplexes will all move to their final channels and power levels.
| link to this comment |
Monty: At that postcode, the predicted coverage of the ArqA multiplex (which carries Challenge) from Belmont is good, though not quite as good as the others.
It's worth checking that your box hasn't tuned in Emley Moor on UHF channel 52 instead. This is expected to be significantly weaker. Some boxes just store the first version of a multiplex that they find. See Digital Region Overlap for ideas on how to resolve this.
If you didn't have digital before switchover, you might still have a Group A aerial, which won't pick up C53 or C60 very well at all. A wideband aerial is recommended. If the cable installation is old, it could be letting in water which increases the losses much more at higher frequencies than lower ones.
The ArqA and ArqB multiplexes from Belmont are still on low power for another week, until Tacolneston (which currently uses these two channels) completes its switchover. The problem could just correct itself next Wednesday - although given that prediction, I would have expected very occasional breakup, not complete loss of channels.
| link to this comment |
John Plant: Derby only provides the three PSB multiplexes. Its purpose originally was to provide the East Midlands BBC One and ITV1 services to viewers using the Sutton Coldfield transmitter.
C48 is Derby BBC A and C46 is Sutton Coldfield D3&4. C29 is Waltham SDN. That suggests your box/TV just stores the first version of the channels that it finds.
The predictions are slightly better from Waltham than from Derby, so I suggest you do a manual retune using the channel numbers on the Waltham transmitter page. See Digital Region Overlap for more ideas on how to get the services you want tuned in.
| link to this comment |
There is also a retune at Sudbury on Wednesday morning, with ArqB moving from C50 to C63. This releases C50 for Tacolneston ArqB next Wednesday, C63 having formerly been Tacolneston Mux 1.
Sudbury is still blocked from going to final channels until Dover completes switchover in June.
| link to this comment |
Dave Caunt: I don't think anything has particularly changed. This week I can't get Mux C (C34) where frequently I'd be able to, but I'm having no more problems than usual with Mux A. I'm in Caversham, Reading.
A lot of tropospheric enhancement has been predicted over the last week: Tropospheric Ducting Forecast for VHF & UHF Radio & TV . This weather condition allows signals to bounce along between layers in the atmosphere without losing a lot of power. It could be interference from overseas stations, or possibly from Rowridge which also uses C32.
| link to this comment |
Tuesday 20 September 2011 6:03PM
Philip Hawkins: Digital UK reckon you have a good chance of locating reliable reception, though that's based on the centre of your postcode and could be worse further down the cliff. It is your best bet, Rowridge itself is shown as a fairly low chance of even variable reception, and zero chance of reliable reception. You will only get the three Public Service multiplexes.
One advantage that digital has over analogue is that the relay can do a full decode with error correction before re-encoding and transmitting. You might have to ask around to see if other viewers have better reception to figure out if the relay is retransmitting a poor quality signal, or if your reception is problematic.
Note that the channels are changing at switchover, which may mean that the channels are also more clear of interference than at present.
Do be aware that reception deteriorates over time as the aerial and particularly the cables weather. If water has penetrated the cables they will drop a lot more signal than if they were completely dry. You should probably plan to replace cables after about 10 years, or if they've been allowed to rub over brickwork or tiles, which damages the insulation.