All posts by Mike Dimmick
Below are all of Mike Dimmick's postings, with the most recent are at the bottom of the page.
jane hore: That doesn't usually happen on analogue. Are you sure you checked the right thing?
It's rare for that to happen on digital as well, it normally goes blocky for a period first. If you're using a separate Freeview box from the TV, try pressing the MENU button on the Freeview box's remote. If the menu doesn't appear, the problem is the connection from the Freeview box to the TV. Replace the SCART cable. If it still happens, try a different SCART socket at either end, because there may be a broken connection.
If the menu does appear, check to see whether the problem occurs when the heating thermostat switches on and off, or a heating pump is running. These can cause a lot of electrical interference, which is picked up by the TV aerial cable. Newer cables, termed 'satellite-grade', with better screening will usually pick up less interference, but getting the thermostat or pump sorted out is a better solution.
Do also make sure your mobile phone is well away from TV aerial cables, as its transmissions can also be picked up and cause problems.
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Mr R B Boyd: Looking at Digital UK's 'Almanac' document, feeding this transmitter is a bit tricky. At switchover, the feed changed from being directly off-air from Ilfracombe to being picked up via Combe Martin (itself fed from Ilfracombe). Ilfracombe was originally fed from Caradon Hill and moved to Huntshaw Cross.
If there's a problem anywhere in the chain from Huntshaw Cross - Ilfracombe - Combe Martin - Berrynarbor, it'll affect your reception.
Digital UK's Planned Engineering Works page does list 'Service Shutdowns' this week on Ilfracombe and Combe Martin - they must have forgotten to update the status for Berrynarbor (and Chambercombe, which is also fed from Ilfracombe).
Looking at the Combe Martin page, it looks like the problem was upstream, as the same issues are reported at the same times.
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jordan: Digital UK's aerial trade predictor shows a good chance of reliable reception from The Wrekin/Lark Stoke/Bromsgrove (already switched, but COM muxes on low power/busy channels) and from Brierley Hill. These predictions are based on a rooftop aerial, but The Wrekin is shown as 100% across the board after the COM muxes move to full power on 28 September (when Sutton Coldfield switches over). The PSB muxes are showing at 100% now.
Boosters generally do nothing useful. Try it without. They're only of any use if the receiver is particularly noisy (which Freeview boxes shouldn't be) or if the signal levels are so low that the box can't detect them reliably, but the interference is still very low.
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James Clifford: Can you get the BBC and ITV channels at all? Did you have digital TV before switchover?
If you had digital before switchover, and you can't get BBC channels or ITV, *and* you had poor analogue reception before switchover, there's a possibility that you actually had the wrong group aerial for Sudbury. It could have been a group C/D. This particularly might be the case if best analogue signals came from a relay, and the aerial was moved around to point to Sudbury for digital. You need a group E or wideband aerial (which cover groups B and C/D) for all services from Sudbury.
If you had clear analogue reception before switchover, you may now have too much signal, causing the signal to be distorted and undecodable. If you have a booster or amplifier, try removing it or turning it down. If you don't have one, or that doesn't help, try adding an attenuator.
If you do have the channels listed above under PSB1/BBC A and PSB2/D3&4, it's likely that your aerial is a Group B (which was all that was needed for analogue reception). A change to a Group E or wideband is likely to be necessary for reliable reception of the commercial multiplexes, both at their current temporary location and their final homes.
I would have expected you to have most trouble with ArqB, which carries Yesterday and Film4, because it's on the lowest power level. That may well point to it being a problem with too much signal.
We need a full postcode to see what the prediction for your location is. A postcode area covers hundreds of homes and usually a few miles, so isn't precise enough. UHF reception can vary greatly over distances of only a few metres.
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Dr. R. D. Feltham: The biggest lie that Digital UK have been propogating is that it will be two stages and done. That isn't true for quite a lot of areas, where there is a clash of allocated channels with those used by another region that is yet to switch over. In these cases there can be many later stages of power increases and sometimes mode changes and channel changes. At Sudbury, there's a channel change in November to get out of the way of Tacolneston's switchover, and final channels and power levels can only be adopted once Dover has switched over next June.
However, power *has* been increased on all six multiplexes already, albeit - for three multiplexes *not* carrying any historical analogue channels - not yet to the final designed level. This power increase is the *source* of problems for a number of people whose aerial system was upgraded for digital, as often those systems have too much gain, causing distortion. That distortion was barely noticeable on analogue, for digital it can prevent the system decoding.
It doesn't help that the strength meters on many boxes mis-report the level if the multiplex can't be decoded, and give the impression that they can handle far higher inputs than they actually can. (On my box, the DTG-recommended lower and upper limits falls at 17% and 58%.) The boxes frequently don't store the best/strongest version, either, sometimes storing signals from further away, again giving the impression that there has been a reduction when in fact it's that a distant transmitter has had a large increase, and your box is now incorrectly storing that rather than the transmissions from the mast your aerial is pointing at.
Again, in some cases, a nearby signal is too distorted after the power increase, preventing a box that does store the best signal from using what should have been the best, causing it to store a weaker distant transmission, which would appear to be a reduction in signal strength.
Please also be aware that signal propogation varies over time, with changes in weather conditions. The scale of this variation can be 100 times or more, and it can vary by frequency, giving different levels of variation on different multiplexes. The small power increases for the muxes yet to reach full power are smaller than this scale of variation, so on some days received levels could be lower than before switchover, despite the actual increase in transmission power. (On the worst days, even the PSB muxes could have a received level lower than the best days for the pre-switchover Mux 1 and 2.)
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Chris: Yes, confusingly, Digital UK report a status of 'working normally' for analogue on transmitters that have switched over, in their reports of planned engineering work. Analogue is off, and it's staying off.
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Briantist: UKTV also gets some subscription revenue. All their channels are subscriber-only on satellite, they are not available on Freesat or Freesat-from-Sky.
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David: North Norfolk is primarily served by both the Belmont and Tacolneston main transmitters. There are a number of relay transmitters - relaying Tacolneston - in the area which provide a full four-channel analogue service now and will provide a Freeview Light service after switchover.
There are also some two-channel relays which broadcast BBC One East and ITV1 Anglia only, in areas that are currently better served by Belmont. At switchover these will also become full Freeview Light transmitters.
In addition there are new relays at Great Yarmouth and Lowestoft, which will start up when Tacolneston switches over in November. Also, some relays in this region are getting the same power as before switchover - usually there is a reduction, as less power is required for digital - and some have a large power increase.
Please check the Digital UK postcode checker for an indication of what you can expect - though there are still some low-lying coastal areas where the signal will be blocked by the terrain.
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Mark: The relay in the Sandringham estate is called 'Kings Lynn' by the broadcasters. It currently only transmits BBC One Anglia and ITV1 Anglia - the signals from Belmont in its coverage area for all four main analogue channels are strong enough, but BBC One and ITV1 are the wrong region (since Belmont was re-attributed from Anglia to Yorkshire in the 1970s).
You should get digital equipment now and retune tomorrow, and on the 17th, to keep receiving BBC Two and Channel 4. You will still get BBC One East and ITV1 Anglia from Kings Lynn on analogue - you'll need to retune again on 9 November (for BBC) and 23 November (for ITV1) to get the new digital signals from Kings Lynn.
Digital UK's predictor suggests that you should get a full service from Belmont.
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Wednesday 27 July 2011 2:48PM
Dave, Briantist: C40 will now be retained for TV broadcasting, along with C39, replacing C61 and C62 which are to be released for 4G. This change happened after most of the plans were made, so they're being redone.
Because the retained channels are in a different aerial group from those being released, they're actually moving allocations of C61 to C49 and C62 to C50 (in general, though it depends on interference). To make this possible, some sites allocated C50 move to C40 and C49 to C39, if they would interfere. It does depend on the aerial groups for the transmitters as well.
It's possible that Patcham's allocations may change before switchover to accommodate changes at other sites, or that C40 gets used by one of the main transmitters, preventing its use here.
Other local TV services are likely to only be available from the main transmitter sites. Certainly the tentative plans published as part of Ofcom's consultation several years ago - based on unfinished plans for the main multiplexes - only included main sites.
For the postcode you provided previously, it looks like Whitehawk Hill would be a reasonable option after switchover, though Patcham is the best option.