All posts by Mike Dimmick
Below are all of Mike Dimmick's postings, with the most recent are at the bottom of the page.
vin: You should be able to receive the HD channels if you have the right equipment. Check that the TV actually has the Freeview HD logo and not just an HD Ready logo. See What does "Full HD Ready" actually mean? | ukfree.tv - independent free digital TV advice for more on this.
If you're sure it is Freeview HD-compatible, you may have interference on C31. See Single Frequency Interference.
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The 9200 definitely works after switchover and I don't see any reason why the revised and updated 9300 shouldn't. Your transmitter hasn't switched yet.
You're very close to a major transmitter - it's possible that you have too much signal. You say you don't have a booster - try adding an attenuator. You should aim for a maximum of 50% signal strength on these Humax boxes - the calibration is way off. Note that Sudbury post-DSO signal levels will be much louder than now.
Mux 2 transmits on two different frequencies, C56 and C68, which are transmitted in different directions. Try the other one. Your box might have tuned in C56 when you're in the C68 area, if it chooses the first version it finds. Look for another version around channel 800 in the guide - if that's better, see if you can swap them over.
C68 is right up at the top end of the frequency range. If you didn't have a Group E aerial fitted, it might not work very well - an original analogue aerial would be Group B and has very little or even negative gain at C68. You would need a Group E aerial to get all the services reliably after switchover as well.
Finally, if damp gets into cables, it increases the loss at higher frequencies much more than at lower ones. That could be causing a problem for Mux 2 but not the others.
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Gerry: The RTE channels are encrypted. I believe you need a subscription from Sky Ireland - they are not listed on Sky UK's Freesat page at FREESAT from Sky - What can I watch? . I don't think Sky offer a 'free' service in the Republic.
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Andy Parrett: Unless there's a bug on the website, I assume this is the page on which the comment box you entered the comment appeared.
As for why you get no sound on these channels, I would have thought the problem would affect more than just these channels. You're most likely to be using the Tacolneston transmitter, to the north-east, which has not yet switched over. BBC Three is carried on multiplex 1, and BBC Four on multiplex B. Mux 1 also carries BBC One and BBC Two among others.
Is there also some picture break-up along with the sound problems? That would point to a general reception problem.
It's possible that your aerial points west to Sandy Heath, which - now it has switched over - carries all these channels on the BBC A multiplex. It's expected to be unreliable, far less reliable than from Tacolneston. Sudbury, to the south-east, is also a possibility but again it's expected to be less reliable.
Tacolneston does use quite high frequencies, and many boxes will store the first version of the transmissions that they find. It's possible that after Sandy Heath switched over, if you retuned (or your box has an automatic retune feature) that it has decided to store weak fringe reception from Sandy Heath, rather than the strong signals from Tacolneston. Check to see whether better versions are stored in the 800s, or elsewhere, and check whether the BBC channels are shown as using UHF C27 (Sandy Heath), C49 (Sudbury) or C63 (Tacolneston). See Digital Region Overlap for suggestions on how to resolve this.
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Antony Antoniou: Indoor aerials nearly always give less reliable results. You won't have line-of-sight to the transmitter because it will be blocked by the house walls and by neighbouring buildings. There will be many reflections off other surfaces and even off people moving around in the house. For best results you should always use a rooftop aerial with clear space all around it.
In addition, indoor aerials are usually just too small. For best results, the elements should be about one-half of the wavelength of the transmissions, so they resonate at that frequency. For Pontop Pike, they should be about 17cm long, with the back element - the reflector - being about 20cm. Fenham uses much lower frequencies and really needs larger elements spaced further apart.
That's assuming the design is actually based on engineering and physics, and not just something that looks good. Many indoor aerials, when tested, are found to be worse than a plain dipole - a single rod of the correct length - which is the baseline against which all other aerials are measured.
At that location you should get better results from Pontop Pike than from Fenham. Make sure the aerial is pointing in that direction - south-west - and the elements are horizontal. Try to position the aerial higher up - but not too close to ceilings - and looking through as little brick-work as possible.
It's possible that the box will still try to tune into the weaker signals from Fenham, because they are on lower frequencies. You may have to manually tune to get it to use the frequencies from Pontop Pike. See that transmitter's page for the frequencies to use.
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Nigel Tutty: I'm not sure where you got April from. The Belmont transmitter starts broadcasting HD services at switchover step 2, on 17 August 2011.
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Brian: Did you retune on the 13th of April? On that date, the Multiplex 2 transmissions from Waltham moved from C23 to C31 because of a clash with The Wrekin when it started high-power transmissions a week later.
You would need to do a first-time installation (also called a Default Setting, a Factory Reset, or Full Retune) to ensure that the box forgets the previous location of the channels. Some will not store channels that they think they already know about.
There's a chance that your box would store channels from Waltham even though the aerial points at Belmont, if the fringe reception is strong enough. Some just store the first version that they find. Check whether there's another copy of ITV1 stored somewhere else, for example at around 800 (this is a common location, but not the only one).
Check what UHF channel the box says it has stored. From Belmont, ITV1 and the other Multiplex 2 channels are on UHF C48. If it is storing Waltham multiplexes, you may need to manually tune in, probably after deleting the incorrectly-stored channels or resetting the box. See Digital Region Overlap for more suggestions.
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Kevin Evans: The Wrekin should give the best results. You're slightly closer to Sutton Coldfield, which will be more powerful after switchover than The Wrekin is now (having switched), but there's a hill in the way, which substantially reduces the signal levels and the probability of reliable reception.
Some multiplexes will still be a bit unreliable as they're still on low power until the end of September, but it's really not worth changing to Sutton Coldfield for six months.
If you had reliable reception from The Wrekin before switchover, and it's now become unreliable, you may have too much signal. If you have a booster or amplifier, try without it.
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Tim: All variants of BBC One and BBC Two, and all other BBC channels, and all Channel 4's channels except 4Music, are free-to-air and do not require the card to decrypt. There are some regional variants of ITV1 that are soft-encrypted and require the viewing card to decrypt: this continues to work even after you stop subscribing. I don't think it's possible to put a free-to-air variant at 103 with Sky - the variant selected is the variant ITV consider most appropriate for the postcode your card is registered to.
Channel 5 has four regions for advertising purposes, of which one is free-to-air and the other three are encrypted. Again, Sky map the appropriate one to 105.
A number of other channels are also available as Free-To-Air or Free-To-View (soft-encrypted). See All free-to-watch channels | ukfree.tv - independent free digital TV advice for a comparison.
If you cancel your subscription, Sky will disable all recording and timeshift functions. You will also not be able to play back previously-recorded programmes. It is possible to just buy the recording features but since it's £10 per month, and you have to get someone who understands what you're talking about, you may as well just keep subscribing.
If you want to keep recording and timeshift features, you should look into a Freesat+ box. The initial outlay is higher but there is no ongoing subscription. You can watch any free-to-air channels.
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Sunday 8 May 2011 11:09PM
Luke: One of the largest sources of intermittent interference is the central heating thermostat. Try adjusting the temperature to turn it on and off while watching the TV. If you get a problem while it's on, get a heating engineer to look into it.
Satellite-grade cables are less likely to pick up electrical interference than the classic 'low-loss' type. If you connect the TV to an aerial socket on the wall, that might be an unshielded type - a shielded one is less likely to pick up interference. You also might be using a poor-quality fly lead - you can get better leads from Online Satellite/TV/FM/DAB Cable, Leads and Connectors sales. you can't pinpoint the source of interference, the BBC can investigate, but you may be charged if they discover it's a problem with your equipment.