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 Knowles: So far, only the BBC SD services have launched at the new power levels, or at the relay transmitters. ITV1/C4/C5 and associated channels, and the other commercial channels, follow in two weeks' time.
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Radan: Astra 1N / Astra 2A / Astra 2B / Astra 2D / Eutelsat 28A (28.2°E) - All transmissions - frequencies - KingOfSat shows it on 10832H instead. ITV plc are consolidating things a bit so they can launch more time-shifts of the England regions (e.g. West+Westcountry separated from Wales), maybe this is why they felt they needed to move it.
I'm not sure what the arrangement is here, presumably UTV have to pay ITV plc to lease space on their transponder (ITV lease the transponder from SES directly, I believe).
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Aerialman: To cut down on equipment costs, only those multiplexes which need different variants have them.
Mux 1 before switchover, or BBC A after, has these variants, due to BBC One's regional services:
Scotland
Northern Ireland
North East and Cumbria
North West
Yorkshire (Leeds)
Yorkshire & Lincolnshire (Hull)
Wales
West Midlands
East Midlands
South (Oxford opt-out)
South (rest of region)
East (Cambridge opt-out)
East (rest of region)
South West
West
London
South East
Mux 2/D3&4 has these versions, matching ITV1 micro-regions:
STV North
STV Central
Border
Tyne Tees
Ulster
Granada
Yorkshire West (Emley Moor)
Yorkshire East (Belmont)
Wales
Central West
Central East
Central South
Anglia West
Anglia East
Westcountry
West
Meridian Thames Valley
Meridian South Coast
London
Meridian South East
C4 and C5 also have advertising regions, but their borders are based on ITV's regions.
Multiplex A/SDN/COM4 has only two variants: Wales and Not Wales. The Wales variant exists to carry E4, which is displaced from PSB2 in Wales to carry S4C.
Pre-DSO Mux B has only one variant. Post-DSO BBC B has several variants to allow S4C Clirlun to be carried in Wales, STV HD in Scotland, and ITV1 HD macro-regions in England and Wales. UTV are supposed to be launching UTV HD in October.
A multiplex is constructed usually by one statistical multiplexing device per variant, which communicates with one encoder per service to be multiplexed. The encoder feeds the compressed pictures to the multiplexer, with an indication of the difficulty of compression. The multiplexer feeds back the bitrate that the encoder must limit the output to, based on how hard each encoder says it's working. That makes a lot of expensive hardware (real-time compression is difficult) which has to be duplicated for each variant. Each encoder has to be fed from the same playout equipment as well, at a data rate usually of 155 Mbps - more for HD. I believe all the multiplexing is now done centrally, so that the national channels don't have to distribute their content all over the place, and also because satellite uplink has to be done from the same place.
So, ITV plc (which owns SDN) doesn't want to add any more variants of SDN if it can help it. Arqiva are likely to flat-out refuse to carry additional variants of Mux C/ArqA or Mux D/ArqB.
In practice this means any service that carries regionalised content has to go on Mux 1, 2 or (after switchover) B. Mux 1 is dedicated to the BBC and getting any additional channels on there is unlikely. Mux B is licensed to the BBC, but Ofcom are required to dedicate some of the capacity to the other PSBs for HD services, and there's no slack. That leaves Mux 2.
Each multiplex transmitted from a transmitter is required to cross-carry all the tuning and EPG data from all the other multiplexes. This is an interesting problem if the encoded multiplexes only have a few variants. Instead of requiring 18 or so variants of each multiplex, instead the Service Information data is gathered together centrally, then distributed to Service Insertion Points for Service Information [SIPSI] - 26 of the main transmitters, plus a couple of locations where the BBC region is different from the ITV one (Kendal, and from next month, Whitehawk Hill). At the SIPSI, the SI data is combined with each multiplex for that region, then the modified multiplex is sent to the transmitter and any sister transmitters from the same region. (For example, for Anglia East/BBC East [not Cambridge], the SIPSI is Tacolneston, which feeds Sudbury.).
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Julie hedges: I'm afraid that Sky require you to keep paying a subscription to use the recording and time-shifting features. It's rumoured that there's a reduced £10 per month rate if you only want recording, not any premium channels, but I can't find this on Sky's website at the moment.
You also won't be able to play back anything you've previously recorded.
Freeview is digital TV through an aerial, rather than through a satellite dish. You would need a Freeview+ HD recorder to record.
You can replace your Sky+ box directly with a Freesat+ box to get recording features. The channel line-up is slightly different: see Compare Freesat and Freesat-from-Sky TV | ukfree.tv - independent free digital TV advice for a comparison.
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Stuart O.: It's consistent with the analogue coverage area published in the IBA's old guides. See mb21 - Transmitter Information - Moel-y-Parc .
The overspill into England is just a consequence of the height-above-ground and the relative low heights of the terrain there. North Wales is just too folded for the signal to get down into the valleys, so numerous relays are required. Even VHF, which bends better over terrain than UHF, was tricky: see mb21 - ether.net - ITV 405 line TV Transmitters - Wales and W England .
This website doesn't have access to the radiation patterns for most of the main transmitters, so it assumes equal power in all directions. It's very likely that power is reduced to the east, to reduce interference into England. We already have to clear Moel-Y-Parc with the Irish authorities to ensure it won't interfere too much with their services, so a power increase is likely out of the question.
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Nicholas Wilmott: ITV1+1 cannot be moved to a different multiplex without either losing the regional variations (effectively meaning it can't be done) or creating 20-odd variants of whichever multiplex it joins.
ITV plc might be more accommodating of creating new variants of the SDN multiplex, because they own it, but as it stands, the two variants are what I said: Wales and Not Wales.
I actually forgot to list the Channel Islands in the list of BBC and ITV regions above. ITV plc - now that they own Channel Television - can now do what they like with the 'Channel 3' half of D3&4 and have decided to add ITV3, rather than ITV1+1, there. Presumably the overhead of additional equipment and manpower for time-shifting (including compliance monitoring) for such a small region outweighs the advertising revenue gained. It's also a special case because no Channel Islands transmitter carries any of the commercial muxes.
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Colin Hooper: At switchover, the transmission mode for all the multiplexes changes. To distinguish between 'before' and 'after' modes, two different sets of names are used: before, we use 1, 2, A, B, C and D; after, we use either PSB1/2/3, COM4/5/6 or the company names BBC A, D3&4, BBC B, SDN, ArqA and ArqB. Legally, in the licences, they actually remain 1/2/A/B/C/D.
The changes are
1 => PSB1/BBC A
2 => PSB2/D3&4
B => PSB3/BBC B
A => COM4/SDN
C => COM5/ArqA
D => COM6/ArqB
Digital UK show Mux B closing and BBC B starting at switchover step 2. This is to accommodate the advance HD network, where a post-DSO-configuration BBC B launched at a limited number of sites (Black Hill, Lichfield, Emley Moor, Pontop Pike, Crystal Palace) in 2009, before those sites switched over. At these sites, 'Mux B' and 'BBC B' are or were in operation at the same time.
The channel line-up is often different for post-switchover configuration due to the increased capacity of, originally, three of the muxes (1, C and D). Mux B is completely cleared to carry HD services. That Mux B change means that the BBC's SD services carried on it before switchover have to move to Mux 1 (PSB1/BBC A), and Sky Sports 1 & 2 move to ArqB, their permanent home.
The commercial muxes have now decided to change to an even higher-capacity mode, which means the line-up on SDN might now be different from Mux A. The process is complete in Wales, allowing identical services in Wales and outside Wales for the first time. (S4C dislodges E4 from D3&4 in Wales, meaning it has to be carried on SDN instead - previously there wasn't enough capacity for E4 and everything else, so CITV and The Zone had to be dropped in Wales to make room.) Once the process is complete everywhere, it's likely some new services will launch outside Wales.
The transmitter pages here should show the correct current configuration for each multiplex. Some sites do show a mix of PSB/COM and company names, and old names - this is where the transmitter is in the middle of switching, or where for technical reasons the new mode has not yet been adopted. If you think there's an error please let us know.
Do make sure that the TV actually carries the Freeview HD logo, not just HD Ready. If you're sure that it does, we really need a full postcode to figure out the problem.
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jb38, Roger Whitman: The reason that the commercial multiplexes are shown as poor from Rowridge, from 18 April, is because Crystal Palace will use the same frequencies from that date.
Viewers who are affected are recommended to change the aerial from horizontal to vertical polarization - Rowridge commercial muxes will transmit greater power on VP than on HP. In Roger's case, Hannington is shown as an equally-good option, as jb38 said.
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Darren Ellis: Normally I'd say that it didn't support 8K mode, but to the best of my knowledge, all PVR-8000T are compatible with it. My parents have one, and have had no problems since Hannington switched over.
Humax's website doesn't list any software downloads for this box at present; it's possible that there were some at some time. You'd have to email them to find out if your box is up-to-date and how you can get it updated.
It is possible that you now have too much signal, given that BBC A is 10 dB (10x) louder than before.
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Wednesday 29 February 2012 10:15PM
Josh Welby: On Freesat, 118 is consistent with the location of other ITV portfolio channels, from ITV1+1 on 112 and ITV2 on 113 through to ITV4+1 on 118.
I think you're thinking of Sky. This site doesn't really cover Sky - it's UK *Free* TV after all. In this case, though, ITV4 +1 can't be added to the Sky platform (even the free service) at this time. Sky froze all new SD channel additions in 2007, as older boxes have hit the limit of memory for storing channels and EPG data. Sky now operate a 'launch queue' - any new channels wishing to join go at the end of the queue, unless another channel wishes to trade its position. Channels can only launch from the queue if another channel closes, or again if they trade an existing EPG slot. ITV4 +1 left Sky so that ITV1 +1 could join. So even though channel number 181 is free, and the channel is already broadcasting from the 28.2°E satellite cluster, ITV4 +1 can't currently be put there.