All posts by Mike Dimmick
Below are all of Mike Dimmick's postings, with the most recent are at the bottom of the page.
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.
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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.
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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.
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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?
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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.
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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.
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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 .
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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.
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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.
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Thursday 13 October 2011 11:45PM
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.