All posts by Mike Dimmick
Below are all of Mike Dimmick's postings, with the most recent are at the bottom of the page.
Michael: no, it is not possible. ITV chose to carry an additional multiplex for ITV1 West, to match the former analogue service, but the BBC have never done so. The ITV1 service only started in 2008, when the former Central South sub-region was split, with the Oxford service joining Meridian North to form Thames Valley, and Ridge Hill broadcasting Central West Midlands.
Often organizations consolidate production in a small number of locations, not necessarily basing them in the area served by the programme. Since the ITV Thames Valley experiment closed down, Oxford news is now based in Southampton.
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Michael King: If you're in Scotland, most of the BBC radio stations on Freeview shut down in the evening to make way for BBC ALBA. If you don't have BBC ALBA you will need to retune your box. This started on Wednesday - the change was scheduled to happen at the same time as the first step of Black Hill switchover, as now all Scottish transmitters have the final post-DSO BBC multiplex configuration.
The stations that shut down are also available on FM (except Radio 4 Extra) and DAB.
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Richard: Darvel's power level on the PSB multiplexes is one-fifth of Black Hill's eventual power level, but because it has finished switching over, and Black Hill hasn't, most of the muxes are actually currently at the same level - 20kW. You are the same distance from both transmitters, although you have clear line-of-sight to Black Hill, while there is terrain blocking line-of-sight to Darvel.
Digital requires far less signal (compared to the noise level) than analogue for a usable signal. Despite the terrain restriction and the antenna being off-beam, you could still be getting enough signal for reliable detection, but not necessarily reliable performance.
Strictly speaking, although it broadcasts the same programme content and adverts as Black Hill, Darvel has always been considered a main station and is fed independently from the studios. Because it is fed the same multiplex content, it identifies as Central Scotland, since the change a few years ago. (Before this change, the multiplexes used the name of the main transmitter in the region, so Darvel identified as Black Hill, which is even more confusing.)
Newer boxes are supposed to tune in the best quality version that they find for the selected region, but this only works if the region name actually matches properly - as I said, some multiplexes from the same site have a slightly different name that your box is considering different.
jb38: I assume where Richard's saying 'channel 22' he actually means Logical Channel Number 22, Ideal World, rather than UHF channel 22. The multiplex Programme Map Table and Network Information Table contains suggested numbers for the EPG, the Logical Channel Numbers, which the box should follow for the best quality version - but it's allowed to store other versions at other free LCNs. These are often found at number 800 onward in the EPG. (LCN 22 is on Mux D/ArqB, so UHF channel 29 from Darvel and UHF C65 from Black Hill, at least for another two weeks, when it moves to C47 - see why we use LCNs?).
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Alan G: No, you require a TV licence if the TV is *capable* of receiving any off-air signals.
If you are in central Scotland, note that the Black Hill and Craigkelly transmitters, and their relays, have only been through the first stage of switchover so far. The second stage happens two weeks after the first stage, and all other multiplexes change mode at all transmitters. If your equipment does not support the 8K mode, you will lose everything, not just the BBC channels.
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Penny: the recorder needs internal tuners so that it can record channels other than whatever you're currently watching. Analogue VCRs had their own tuners as well.
In practice the recorder cannot record what's being displayed by the TV, because they don't contain video compression technology. They record the raw compressed bitstream coming off-air or from the cable, then pass that through the decoder when you play back. Raw uncompressed recording would take way too much space.
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Dale: Some channels are designed to be '4:3 safe', that is, all the significant content will fit onto an older 4:3 format screen, while others go for 16:9. Some even have a compromise at 14:9, with black bars top and bottom on a 4:3 set and to each side on a 16:9 set.
The BBC recently moved the logos on BBC Three and BBC Four to the far top left, making them widescreen-only, rather than 4:3 safe. BBC One and Two have to remain 4:3 safe until switchover completes, and BBC News content runs on BBC One overnight.
I don't know why Sky would be staying 4:3 safe, they have never broadcast on terrestrial analogue, there's very little analogue cable around any more, and the Sky platform has been all-digital since 2001.
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Richard: I was looking at Terrain - shows radio profile between two UK sites to optimise you DTT, Freeview, DAB or analogue TV reception . That site suggests using Multimap to find the National Grid Reference, but Microsoft have since closed it down after introducing their more recent Bing Maps service. Instead I use nearby.org.uk to get the postcodes for a co-ordinate.
It does indeed show that the path to Darvel relies on refraction over Queenseat Hill and the Whitelees wind farm.
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David Kennedy: Looking at the Curtis International website, I found the manuals for both set-top boxes they manufactured, the DVB102UK and DVB203UK. Both say that they support the 8K mode that the BBC services now use, and all the other services will use after stage 2 next week.
However, it could be one of the boxes that has trouble with some multiplexes in one mode and some in another. In this case, you may find it starts working after next Wednesday's retune.
Make sure you're doing a First-Time Setup, using the procedure on page 20 of the DVB102UK manual. Some boxes get confused when they have previously had a full set of services.
Manuals -- CURTIS INTERNATIONAL
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Ian: The coverage areas for the 'interleaved' multiplexes are extremely limited, while it is intended that the three COM muxes should have equal coverage.
You can see the proposed map for NEW7 at Interleaved Frequencies maps | ukfree.tv - independent free digital TV advice though note that this is based on the template and not on a practical aerial, so the covered area is likely to be even smaller.
As for wideband aerials, you had to have one for digital from Waltham before switchover, so there is in fact no change. The planners have only been required to make the PSB channels available within the old analogue aerial group - the commercial muxes are seen as an add-on service which is why they are *not* required to be made available from the relays.
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Thursday 9 June 2011 1:24PM
Gordon Comley: The most likely explanation is that you have too much signal. If you have a booster, try removing it or turning it down - if that doesn't help, remove the booster and try adding an attenuator.