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All posts by Mike Dimmick

Below are all of Mike Dimmick's postings, with the most recent are at the bottom of the page.

Nick: "Why does a non hd freeview box not show the channels used for hd, albeit not in HD?"

Because the HD signals are transmitted with a new modulation standard, DVB-T2. A regular DVB-T box simply cannot understand the data stream that's transmitted, it just sees it as very loud noise.

"How do I align to Sudbury please?"

Cheap meters simply show a raw signal strength across the entire UHF band. These are basically useless. You'd be better off selecting the manual tuning screen on a Freeview box, telling it to tune in a known frequency (e.g. C44) and watching the strength meter on the tuning screen. That assumes the box shows the strength/quality on a specific channel before actually tuning it.

Proper meters allow you to select the channel to monitor. Professional equipment does a full decode and recode of the signal, comparing the actual received signal and the ideal to get a quantity known as the Modulation Error Ratio. The aerial should be positioned to get the best MER. However, equipment that does this is quite expensive: the Promax TV Hunter, which is fairly basic, is over £400.

Unfortunately most Freeview boxes have a pointless quality meter, showing the number of uncorrectable errors. You need to know how many errors are being corrected and optimize for the fewest errors, as this will give the most chance of reliable reception in adverse weather conditions.

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Nick: Unless you changed the aerial for a wideband at some point in the past, you should do so now. An aerial erected for Aldeburgh would be a Group A aerial, designed for C21-C37, whereas Sudbury requires a Group E or wideband designed for at least C35-C68. A wideband is recommended to ensure that you can still pick up the COMs in the future: it's looking like they will have to move again to release even more spectrum for mobile phones.

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threewheels: There's a site dedicated to the rebadged Vestel units at Unofficial Vestel PVR Information (UK) - Home

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Andrea: It looks to me as though the digital versions of ARD/Das Erste and ZDF, plus other free channels, are already available from the same satellite cluster as the analogue versions. Reportedly they've been available since 1996.

If you can already get Eins Extra and ZDF info, you don't need to do anything. If not, you'll need to get a digital satellite receiver and plug it in in place of your current analogue receiver. It's probably worth getting an HD-capable receiver at this point. Check for DVB-S2 and MPEG-4 AVC (also known as H.264) support. I believe there are many free-to-air receivers on the market - you don't need a subscription to a pay-TV service.

There appear to be many Electronic Programme Guide providers, such as tvtv. That's not a recommendation, just one I found. The receiver should say which service it works with. You don't *need* an EPG but without one you would have to tune in the services yourself. See…html for the frequencies to tune in.

Some of the SD services like RTL Deutschland want a yearly payment for their HD services, branded 'HD+'. It appears that 'HD+'-branded receivers come with an HD+ decryption card with a year's subscription, the renewal fee is currently 50. This is a standard CI+ card so it should be possible to add one to a standard receiver later, should you decide to.

The analogue transmissions will be replaced by additional HD channels from ARD and ZDF. Their main services are already available in HD, at no charge.

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Pauline: You should use *one* connection from the receiver to the TV.

HDMI should generally work. If it doesn't work at all, even after swapping cables, see if you can borrow a different box that is known to work with HDMI. If that works, get your receiver repaired or replaced; if not, get the TV repaired or replaced. You shouldn't spend more than £5 on an HDMI cable - gold-plated contacts are barely worth it, expensive cable is not worth it.

The problem may be down to copy-protection. The TV has to tell the receiver that it really is a TV, and not some other box that allows the picture to be extracted, before the receiver will send digital signals to the TV. See if the manuals say anything about enabling HDCP.

If the broadcaster is sending the 'content protection' flag with the broadcast, and the receiver hasn't done an HDCP handshake with the TV, it is supposed to disable the HDMI connection.

SCART and component video (aka Y-Pb-Pr) are analogue connections. The component video cables do allow higher-resolution connections than SCART, which is standard-definition. However, the copy-protection systems allow the broadcasters to tell the receiver to send SD-quality pictures over the component cables, for content that they want to protect. I'd concentrate on getting HDMI working rather than on using component cables.

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Indoor aerials | Installing
Monday 23 April 2012 3:00PM

Charlie: The licence fee funds the BBC. It doesn't fund any of the other services you can receive, or any of the ones you can't.

The BBC outsource licence fee collection to Capita. The service costs £124m, 3.4% of the money collected, a reduction from 3.5% the year before. Capita proposed moving jobs from Bristol to Darwen in Lancashire, I've no idea if it happened: 200 TV licensing jobs could move to Darwen (From Lancashire Telegraph) . £2m is not an unreasonable amount for relocating 200 jobs and making 150 redundant.

The TV licence fee is frozen for the next five years, while the government have offloaded a number of additional services which they used to pay for, like the Welsh language channel S4C, the propaganda BBC World Service, and the spying organization BBC Monitoring.

What you do get is four full-time TV channels (BBC One, BBC Two, BBC News and BBC Parliament), four half-time channels (BBC Three, BBC Four, CBeebies, CBBC), ten national radio stations and 51 local radio stations, plus a high-quality website.

Council Tax is set by your local council, plus the local police and fire authorities, but the percentage difference between the bands is standard across the country. It is widely considered to be a regressive tax, the reduction from Band D to Band A is far less than the difference in the value of the property: a Band A property pays 67% of the rate for Band D, but Band A properties were worth less than 59% of the lowest edge of a Band D property, 51.2% of a mid-band property. Meanwhile, on the other end of the scale, a Band H property would be worth at least 3.6x a Band D property (upper edge of Band D: more than 4.7x the lower-edge value) and yet only pays twice the rate.

There's certainly an argument for making the licence fee more progressive, based on the ability to pay rather than a flat rate, but the first argument to overcome is keeping the BBC in its current form at all.

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Robert: Everyone's case is different depending on their exact location. Signal levels can vary greatly over just a few metres - good positioning of the aerial is important. How important it is, is down to the actual signal levels available: in areas with high field strength, and low or no co-channel interference, it's not important; in areas with high levels of interference, it's very important.

Signal levels vary with weather conditions. TV signals behave like light - they reflect, they refract, and they can be selectively absorbed by the atmosphere, depending on the amount and size of particles (dust, raindrops). The transition from night to day and day to night usually sets up different layers of warm and cold air, and signals can bounce off the boundaries between these layers rather than passing through, usually called 'tropospheric enhancement'. Less-common conditions, like extensive high pressure, can cause layers where the signals bounce along between upper and lower layers, exiting a long distance from the transmission point: this is usually called 'ducting'. Generally this increases the level of interference: if you don't have enough signal margin, the difference between the level of the wanted signal and the level of the interference, it causes the picture to break up. The distance between transmitters using the same frequencies is far enough apart that, for people in the expected coverage area, changes in weather conditions shouldn't cause problems 99% of the time.

The old advice to retune if you had a problem was because a number of boxes had buggy software that would corrupt their own settings over time. Resetting to factory defaults and retuning restores a good set. However, that advice is flawed after switchover, because so many boxes will happily store distant signals that are too weak to be reliable. I now tend to advise manual retuning if the person with the problem is predicted to have good enough signals. Only after confirming that the box has actually tuned to the correct transmitter is an aerial check indicated.

There are some boxes, however, which have no manual tuning functions. I was reading a TV manual a couple of days ago to try to help someone - can't recall which brand - that had manual tuning for analogue, but not for digital.

Equipment that's now on the market is *supposed* to tune to the best quality signals available, and if it detects more than one region, it's supposed to ask which one you want to store. However, I'm aware that the Humax Freeview HD equipment still doesn't do this correctly.

Retuning when you have a problem, and that problem is caused by higher-than-normal levels of interference, is likely to cause many boxes to store services from the wrong transmitter. In the wrong conditions, even those that normally do it properly might get it wrong, if the wanted signals are particularly badly affected.

For your particular case: make sure that your receiver is correctly tuning into the Oxford transmitter. BBC One (logical channel number 1) should be found on UHF frequency C53, ITV1 (LCN 3) on C60, ITV3 (LCN 10) on C62, Pick TV (LCN 11) on C59 and Yesterday (LCN 12) on C55. If that isn't the case, see Digital Region Overlap for ideas on how to make it do it, or replace the box with one that does it right.

For you, a box that stores the first version it finds could well pick Oxford for the BBC, but Mendip for all other services, if the Mendip services are strong enough to be decodable at all.

If it is definitely tuned to Oxford, then you should be looking at aerial problems. Looking at that postcode, there appears to be a stand of tall trees to the north-east of the buildings, which would be approximately in the direction of the transmitter. You may find you get better results if you can aim the aerial between the trees, or if you can get them reduced in height so the aerial can look over them.

You've posted before that you have multiple aerials for multiple TV points. You're likely to get more consistent results from one well-placed aerial, with the signal being distributed to the TV points. Look for installers specialising in MATV (Master Antenna TV) or SMATV (Satellite + Master Antenna TV) systems. The installer should ensure that the signal levels at each TV are adequate to ensure reliable reception.

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Mark B:

1) Yes, most of the transmissions are 'free-to-air', they are not encrypted and only need a standard decoder. There are a few (e.g. Pick TV) which are encrypted but can be decoded by any Sky card, even if you're no longer subscribing.

2) No. A Sky+ box's recording and time-shifting features only work if you have an active subscription. You also can't play back anything you've previously recorded. It's reported that you can restore these functions by paying a £10/month subscription but I can't find it specifically on Sky's website.

If you want recording and time-shifting functionality you'll have to get a Freesat+ box. (You can also get non-branded free-to-air satellite receivers, which can receive all the channels, but you have to tune it yourself, including retuning as and when services move to a different frequency, and it won't have access to Freesat's accurate recording data.)

The Freesat box won't be able to decode a few channels that a Sky box will. For a comparison of what's available, see Compare Freesat and Freesat-from-Sky TV | - independent free digital TV advice .

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Heather Naslin: When the channels moved from the Astra 2D satellite to the Astra 1N satellite, they mostly stayed on the same frequencies. You shouldn't have needed to do anything.

ITV have been moving services around a bit, so if they've moved your preferred regional service somewhere else, you might need to retune. If you have a Sky box, it should have retuned automatically, but you might need to check that the viewing card is properly inserted. Freesat boxes are supposed to retune automatically as well, but some of them need to be powered off and on again before they retune. Others actually have to be told to retune.

If you have a generic free-to-air receiver, not Freesat-branded, you'll have to retune it yourself. See for the frequencies to use.

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Kevin: No transmitters are being taken down that have already switched over.

There are a few transmitters which have closed at switchover, but only if they were being replaced or the service they carried was removed. Three BBC One Wales/S4C transmitters in north-east Wales (Flint, Bagillt and Holywell were replaced by much better services from the Storeton transmitter (which is in England, on the Wirral peninsula). Three ITV1-only relays in north Hampshire were switched off completely as they were there to provide the Meridian Southampton service to viewers who would otherwise get best reception from Hannington, which used to provide the Meridian West, later ITV Thames Valley, service. That service closed and merged into Meridian Southampton in 2009.

There have also been a couple of closures in Dundee (Camperdown) and on the Wirral (Bidston), due to the buildings that the relays were erected on being demolished. In both cases, new relays (Dundee Menzieshill, Sunningdale) have been erected on nearby buildings.

I don't know whether the broadcasters will re-evaluate the coverage of all the relays at any point, and decide to shut some down. Treharris was predicted to cover 4,700 homes which couldn't get even one of the commercial multiplexes from Wenvoe or Pontypool; it also feeds the Abercynon transmitter which covers 2,300 households. The cut-off for erecting a relay used to be 500 households.

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