All posts by Mike Dimmick
Below are all of Mike Dimmick's postings, with the most recent are at the bottom of the page.mike clowes: Try unplugging the box from the mains for about ten minutes, then plug it back in. It may be the same problem that is causing some boxes to switch back to BBC One when you select a different BBC channel.
'Technika' appears to be Tesco re-branding other people's hardware and I'm finding it difficult to find support resources for this box.
Dave: While this is true, it's unlikely to apply to mike clowes' problem as he's referring to a Freeview HD box, which have to comply with a tighter spec to get the Freeview HD logo. A list of known incompatible equipment is available at http://www.digitaluk.co.uk/2kequipment and there's a list of equipment known to have problems with the Split NIT at http://www.digitaluk.co.uk/splitnit , though that problem first surfaced in 2008. (RG47SH)
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Matt James: Mendip PSBs are good but at the moment the commercial muxes are low power, and the prediction is poor or non-existent. Some of them power up on 28 September and change to other channels, which leaves your prediction poor. It reaches final modes and power levels on 28 March 2012 after Rowridge DSO 2, but there will be a number of changes in interference as the switchover programme completes and other transmitters go to full power. The end result will be some muxes good, some variable.
Hannington's results are expected to continue to be variable after switchover, with many of the probabilities lower than they are now.
Rowridge COM muxes clash with Marlborough's channel allocations. This will actually harm your reception of Marlborough and it goes from Good to Poor in April 2012 once they've gone full power after Crystal Palace DSO. It also means there's no prediction for Rowridge COM muxes on either polarization.
I'd wait until next April, see what you actually get from Hannington and how bad the impact on Marlborough is, then decide whether to stick with Hannington or try Mendip instead.
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chass: Sometimes the broadcasters change the region name slightly to indicate that they've changed the multiplex line-up slightly, adding or removing a dot at the end or adding a space before the dot. I don't know if this was in the D-Book specification, but it causes problems for some boxes.
Is there no way to get it to store the channels from both 'regions'? If it won't, try selecting the 77 channel variant then manually tuning whatever multiplex carries the channels that you're missing. Mux A and D both carry 27 channels, so it could be either, but it's most likely to be Mux A as ITV3 is carried on this mux. At the moment, Mux A is on C22.
You should also see whether there are any updates available for your box, and if not, let the manufacturer know about the problem.
No multiplexes have yet changed frequency at Fenton. Mux 2 will move to C33 on the 20th, to avoid problems when The Wrekin, Bromsgrove and Lark Stoke start using that channel for HD services. You will need to retune again to keep ITV1, Channel 4, Channel 5, ITV 2, Channel 4+1, More 4, E4 and ITV1 +1. The main switchover is in September.
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John Stone: No, that's deliberate.
DVB-T was designed to cope much better with reflections than analogue does. In fact, it does it so well that reflections can actually help. It's possible to set up additional transmitters on the same frequency that transmit the exact same signal, so they look like they're just reflections of the main signal. This only works as long as they are properly synchronized, and the paths from the transmitters to your aerial aren't too different in length. The limit in difference is about 75km for DVB-T and DVB-T2 with the modes we're using.
Using the same frequency from multiple transmitters is called a Single Frequency Network, and it's a great way to improve coverage in an area without signals bleeding too much into other areas and without having to allocate different frequencies. The same technique is used for DAB - the maximum distance between transmitters is much further for DAB and the same frequency is used for the BBC national radio services all across the country.
For best results with the type of aerial normally used, the transmitters have to be in roughly the same direction. For you, Rouncefall is at 7° east of true north and Sudbury at 21°, within the normal zone that aerials pick up from. Your aerial is likely to pick up Rouncefall, helping your reception, without you doing anything.
In fact I think that the signal strength from Rouncefall could be too great. 2.2km away from a 4kW transmitter isn't very far. You would have to remove any boosters, and maybe add an attenuator if you have problems.
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Rich Greenslade: I've found a couple of support threads at Philips/Pace Freeview HD PVR - HDT 8520 thread - Philips - Digital Spy Forums and Philips/Pace HDT 8520 HD-PVR Master thread inc. Bug and Issues List [Part One] - AVForums.com . No sign of this problem being reported, though.
It could be a case of too much signal. If you have a booster, try removing it.
Also look at the Single Frequency Interference page to see if there might be anything else using C26. (RG47SH)
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John Rowlinson: Digital UK predict that you should be able to get HD services at least as well as the BBC and ITV/C4 main multiplexes.
'Bandwidth' strictly means the width of the transmissions within a channel. All multiplexes have 8 MHz bandwidth whether SD or HD.
It's possible they meant that the radiation pattern is limited, and it is a bit, but it's not that limited. Unfortunately the broadcasters won't tell us exactly what it is.
You'd normally expect to get perfect reception at such a short distance from the transmitter, even if the radiation pattern is limited in your direction. However, the PSB multiplexes share channels with the COM multiplexes at Rowridge on the Isle of Wight, which will be transmitting in vertical polarization from April 2012, and from Rowridge and Crystal Palace in horizontal polarization. The COM multiplexes at Hastings share channels with Crystal Palace PSBs, and other south coast PSBs. It'll still be good, but the probability isn't 100%, meaning you might have to site the aerial more carefully to get best reception.
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Martin: it's possible that the TV has decided to store signals from The Wrekin, which is now at high power, rather than from Sutton Coldfield. You have clear line of sight to both transmitters, and The Wrekin is a bit closer. The field strength calculator at Field Strength Calculator reckons the signal from The Wrekin would now be stronger. About 10 dB or ten times stronger, in fact.
There are a couple of possibilities. The first is that because The Wrekin is a bit off-beam, but not that far, the signal is too low to be reliable but not too low to be detectable. The second is that the TV has trouble with the 8K mode or with a split NIT - check the lists at http://www.digitaluk.co.uk/2kequipment and http://www.digitaluk.co.uk/splitnit although these lists are not comprehensive.
Finally there's a possibility that the combined signals from all the transmitters you can see is now too large for your equipment to handle. If you have a booster, try removing it.
To avoid the problem, delete the BBC channels then manually tune C41. You're likely to get the same issue on ITV channels after the 20th.
Digital UK's trade predictor is showing non-existent results for COM muxes from Sutton Coldfield after switchover, because they have been allocated the same frequencies as the PSB multiplexes at Moel-Y-Parc, 57km to your north-west. You are expected to get reliable results on these muxes from The Wrekin once they move to final channels in September. (RG47SH)
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Adrian: Ridge Hill BBC A has started at high power on C28, 530 MHz. Digital UK's prediction for your reception from Pontypool is shown as poor on SDN, ArqA and ArqB, and non-existent on BBC A, D3&4 and BBC B.
On the 20th, you're likely to lose SDN and ArqA if you do have them now, because the other public service broadcaster multiplexes at Ridge Hill will go to full power.
You might be getting some assistance from Mynnydd Machen on the PSB channels (same frequencies as Pontypool, acting as a Single Frequency Network).
Digital UK's predictor shows Mendip as your best option for all six multiplexes - excellent chance of reliable reception. Wenvoe is variable for PSBs and poor for commercial multiplexes.
If you want the Welsh services, including S4C, you may need a combination of aerials, or consider Freesat.
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Friday 8 April 2011 2:03PM
Reading
brian gibson: While it's recommended that boxes tune into the strongest signal, this isn't enforced. Some equipment just tunes into the first signals it finds. For suggestions, see Digital Region Overlap.