All posts by Mike Dimmick
Below are all of Mike Dimmick's postings, with the most recent are at the bottom of the page.
Jim: Yes, you really need a receiver that supports DiSEqC to switch between the different feeds. You can get manual switches but it's likely that different satellite clusters will use the same frequencies for different channels.
There are Freesat receivers that support DiSEqC - you would need to put it in non-Freesat mode to tune in the other satellites. There are also Free-To-Air receivers, not Freesat-branded, which will treat all satellite clusters equally, but won't show all the Freesat EPG data. Sky boxes do not support DiSEqC.
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Briantist: The BBC have not yet applied to renew BBC B, it runs out in 2014. The renewal, if they take it up, will run to 2026.
Mux 1/BBC A will be 'until the Royal Charter is renewed', the next renewal is in 2017. I agree that it's likely to be the last to be replaced.
I'm also not sure about 'only HD carried in DVB-T2', implying that SD services would be excluded. Perhaps you meant 'HD only carried in DVB-T2', meaning HD wouldn't appear on a DVB-T multiplex, but SD could be carried on DVB-T2.
Charles Stuart: I would expect that if SD *was* carried on DVB-T2, it would be encoded with MPEG-4 AVC (aka H.264, MPEG-4 Part 10, ISO/IEC 14496-10) as HD is. That could reduce the data rate required substantially, compared to MPEG-2 Video as used for current SD services, but it all depends on content and the abilities of the decoder.
Currently the number of video streams per mux varies from seven (BBC A) to 11 (SDN) in approximately 24 Mbps. If layers 7 and 8 were deployed with the suggested mode capacity of 38 Mbps you could get 11 to 17 MPEG-2 SD video streams; with additional efficiency of AVC you might get 20 to 30. Layer 9 is expected to provide 35.8 Mbps providing 10-16 SD MPEG-2 streams.
HD has five times as many pixels as SD (comparing 1920x1080 to 720x576), the BBC usually run at 1440x1080 which is 3.75x. HD bitrate for video averages 8 Mbps - but the BBC think they can squash to 6-7 Mbps, allowing one more service - compared to about 3 for BBC One SD. So we should perhaps expect AVC to deliver similar results with around 40-50% of the bit rate of MPEG-2, for the same number of pixels.
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Ian Matthews: You might have your TV in the wrong mode. It should be set to PAL I for the UK.
Different countries used different frequency offsets for different components of the analogue signal. Most of Western Europe used System G on UHF, which - compared to the UK and Ireland's System I - uses the same method of encoding the brightness and colour information, and the same frequencies, but a different method of encoding sound and a different frequency.
Stereo sound was a later add-on, and some countries in Europe did use the same NICAM system as us, but again, on a different frequency.
SCART cables carry the sound on separate wires, so the connection from your Freeview box - if it is separate, not built-in - would not be affected. It would only be affected if your TV didn't have a SCART input and you had to watch the output of the box by tuning in a spare channel preset.
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Briantist: Agreed, there has to be a substantial amount of voluntary take-up - just like the switch to digital - before there can be any mandatory switch-off plan. To get voluntary take-up there has to be a compelling reason to do so.
However, many surveys have indicated that people are more interested in greater choice than in better picture quality. There are some people vocally against reductions in quality to cram in more channels, but the majority would seem to prefer more choice. Perhaps a bit more of both is what's needed.
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Briantist: All these changes (including the Meridian, London and NI changes) are already in the table incorporated into the licences, available at Ofcom | Supplementary licence documents in relation to DSO ('Digital Terrestrial Broadcasting Stations for Multiplex Licences' or 'Table of Digital Stations')
I'm actually surprised they've provided new documents in the 'DSO Details' section for the three regions yet to switch. I'd assumed that they wouldn't be updated further, given that there were three updates to the licences table at the end of last year without corresponding updates to 'DSO Details'.
There are a few notes in the 'DSO Details' documents not in 'Table of Digital Stations', in particular places where BBC A will start up on one frequency and then change to another at stage 2.
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Dave Lindsay, Briantist, Pat Hughes: The tender documents at RT: NI Project specifically say "integrated into Freeview *HD*". To me that implies DVB-T2, although it isn't specifically stated.
I know Brian's belief is that DVB-T2 muxes will carry HD only, but I think that's a promotional issue to drive voluntary take-up of T2 equipment - the value proposition of a greater number of new SD services is considered lower than the value of fewer additional HD services. I'd argue caution on that point, several surveys have indicated viewers are more interested in more choice than in better quality for the choices they already have. (You only have to look at the behaviour of the commercial muxes, continually squashing in more channels!)
The documentation doesn't state anywhere what mode is proposed. Without that information we can't tell what the coverage will be. It does appear from Saorview's map that Claremont Carn will be permitted to broadcast a lot of power to the north, providing a lot of the coverage - the mini-mux is there to fill in where overspill from the Republic doesn't reach. It *is* expected that the mode is substantially more robust than any of the options used by the main six muxes, and therefore much more coverage will be obtained from the low power levels available.
BT Vision boxes may well be able to decode the overspill Saorview transmissions, which are MPEG-4 AVC (H.264) carried on DVB-T. But I don't think we should assume that the mini-mux will use the same mode - it's not carrying as many channels, for a start.
The tender process should now have reached the dialogue phase with any applicants that have been shortlisted, but I can't find any public notification of who they are, or any more documents. We may not find out any more details until the end of March, when the contract is due to be issued.
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john preece: Generally you would connect a DVD player to a TV using a SCART connector. If the TV doesn't have a SCART (or doesn't have one available) you may be able to connect using HDMI, if it's an HD TV and a recent DVD player. After that, check for a set of phono sockets marked 'video', 'audio L' and 'audio R'.
To watch a DVD, you then use the TV remote's 'source' or 'input' button to select the socket or sockets you connected it to. It should show a menu or cycle between the options - they're usually called AV 1, AV 2, etc, although some TVs now include the name of the connector.
If you don't have enough SCART sockets on the TV, you can get a SCART switch box that allows you to switch from one device to another.
Very few DVD players contain the RF modulator necessary to make the DVD player appear, to the TV, like an analogue TV station that you can tune in to. This is the worst quality option anyway. If really necessary, you can buy an external RF modulator that plugs into the DVD player's SCART socket.
If you also have a Freeview box, it may have a second SCART socket. If the TV doesn't have enough SCARTs, it may be possible to plug the DVD player into the Freeview box, set the TV to display the Freeview box, and then set the Freeview box to display the DVD player (again, look for a 'source' button on the remote).
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Peter: Yes, exactly 100 kW.
The coverage still will not be equivalent as the commercial muxes have chosen to use a less robust, but higher-capacity mode. They have started making this changeover already. In addition, the PSBs got the best channel allocations, the commercial muxes will be subject to greater interference from other transmitters.
Finally, Rouncefall's transmissions help to reinforce Sudbury's coverage in many areas, but it only transmits the PSB services. The COMs get no help from Rouncefall.
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doug: These things are unrelated.
Nearly all free-to-air channels transmitted from satellites are included in Sky's Electronic Programme Guide. There are a few channels that aren't listed, mainly because Sky's listing prices are extortionate, but also Sky have to support old boxes that have limited memory, so no new SD channel can launch unless an existing one closes.
Sky (both the paid and free services) and Freesat use the exact same transmissions from the same satellites. You just can't watch any subscription channels on a Freesat box, because they are encrypted, and you need the Sky box and card to decode them. There are a few channels that require the Sky box and card, but don't need an ongoing subscription - these are called 'free-to-view'.
To watch a channel that isn't in the EPG on a Sky box, you go to Other Channels (press Services on the remote) and enter the necessary parameters. You can find parameters at sites like Eurobird 1 & Astra 1N/2A/2B/2D at 28.2°E - LyngSat or Astra 1N / Astra 2A / Astra 2B / Astra 2D / Eurobird 1 (28.2°E) - All transmissions - frequencies - KingOfSat .
The RF output is to allow TVs (usually additional TVs) to display the channel that the Sky box is decoding. This is tuned in as if it were an *analogue* TV station. You can select the UHF channel that it uses, and the installer may have already selected something that isn't in use in your area, so we can't really tell you which channel to tune into. Put your postcode into the box at the top-right of this web page to find suggested channels to use. If the Sky box is on, not in standby, it should be found when you use the automatic tuning feature of the TV.
It's recommended that you avoid channels over 60, because they will be used for 4G mobile phone/broadband once digital switchover is completed. Channels between 31 and 38 are due to be released as well, they could end up being used for digital TV (Freeview) or for something else.
I'm not aware of any Freesat box that has an RF modulator built in. If you do want to distribute the output of a Freesat box, you can buy an RF modulator that plugs into a SCART socket.
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Thursday 19 January 2012 4:54PM
Tim McEwan: I'm afraid I can't find a detailed spec or manual for that TV online.
For Freeview HD, the TV has to support the newer DVB-T2 standard and the BBC's method of encoding the programme guide (this is a very rudimentary copy-protection measure). Equipment that supports both should have a Freeview HD logo on the packaging somewhere. You could check to see whether the manual mentions DVB-T2. If it only mentions DVB-T, I'm afraid you'll need an additional Freeview HD box.
If the TV definitely supports Freeview HD, not just 'HD Ready', the most likely answer is Short Reflector Syndrome: http://www.wrightsaerials….pdf .
Wideband aerials aren't very good at the lowest frequencies, but you don't have much choice with Sandy Heath as the commercial multiplexes are in the middle of the frequency range, and a Group A aerial won't receive them. The cut-off is very sharp for frequencies above the range that the aerial is designed to handle.
If you can get into a manual tuning screen for the TV, it may be possible to show the signal strength for C21 and compare it to the strength for C24 and C27. If they're similar, it's the TV, not the aerial.