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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.

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Beacon Hill (Torbay, England) Full Freeview transmitter
Tuesday 11 October 2011 3:54PM
Wareham

Chrisonahill: The signals from Beacon Hill are at their final power levels. It's unlikely that there will be further power increases.

If your location is still BH20 6JG, I would guess that Rowridge on the Isle of Wight would give better results than either of the mentioned transmitters, once it switches over in March. You're likely to get best results using a vertically-polarized Group A aerial, once the VP services are running at full power from 18 April 2012. The commercial multiplexes from Rowridge will use the same channels as Stockland Hill, which will have some effect, though the use of VP should help (as Stockland Hill is horizontally-polarized).

Your reception of commercial multiplexes from Stockland Hill is liable to be clobbered by Rowridge once it completes switchover, even with Stockland Hill's power increase, and Rowridge's horizontally-polarized COM transmissions being one quarter of the power of VP.

Please note that this is my guess, rather than a prediction from Digital UK, whose website is currently not accepting that postcode.

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John Hodgson: Stow is a 'Freeview Light' transmitter, broadcasting only the public-service multiplexes. The channel line-up should be:

1 - BBC One Scotland
2 - BBC Two Scotland
3 - ITV1 Border Scotland
4 - Channel 4
5 - Channel 5
6 - ITV2
7 - BBC Three
8 - BBC Alba
9 - BBC Four
13 - Channel 4+1
14 - More 4
28 - E4
33 - ITV1 +1
70 - CBBC Channel
71 - CBeebies
80 - BBC News
81 - BBC Parliament
301 - BBC Red Button

and a number of BBC radio stations and text services.

Please see Will there ever be more services on the Freeview Light transmitters? | ukfree.tv - independent free digital TV advice for the explanation (short version: cost).

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Matt: The numbers are the percentage of locations, within the 100m x 100m National Grid square that the centre of your postcode falls into, that are predicted to have (on average) sufficient signal margin to be reliable 99% of the time, and 50% of the time, respectively. It's a measure of the difficulty of locating an aerial within that square and how coverage might vary between you and your neighbour.

The prediction is based on an aerial with CAI Standard 1-class gain, and loss of 3-5 dB in the cable depending on frequency, but the template for cross-polar and front-to-back rejection is weaker than such an aerial would normally achieve. The prediction allows for losses if the signal path goes through a square made up mostly of woodland or of dense buildings but it only allows for average losses. They might be higher or lower than allowed for.

The prediction calculates both the signal from the wanted transmitter and the interference from unwanted transmitters, including adjacent-channel interference.

Short of actually going and surveying every grid square in the country, this is probably the best we can do, but it's always going to give 'wrong' answers for some people.

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Neville Wake: Upscaling cannot create resolution that didn't exist in the original content. An upscaler is only of any use if the upscaler in your TV does a poor job.

Freeview HD channels broadcast (mostly) content that was recorded and processed in HD. The BBC HD channel carries only HD content, the others have a mix of HD and upscaled content depending on how it was sourced. The majority of new programmes are made in HD. The EPG information for BBC One, BBC Two, BBC Three and BBC Four ends with 'Also in HD' if the programme was made in HD and is being simulcast on BBC One HD (for BBC One content) or on BBC HD (Two/Three/Four).

Giles: Ofcom are still deciding what to do with UHF channels 31-37 after DSO completes. The transmitter provider Arqiva have been asked to prepare a Reference Offer for broadcasting up to three new multiplexes using this range of channels; the predicted coverage is lower than for the current six multiplexes. The new capacity could be used for SD or HD channels - that will be up to whoever bids. Ofcom could still decide to release these channels for services other than TV broadcasting.

Over time I would expect the existing multiplexes to be upgraded to DVB-T2 in order to get more capacity from the same spectrum, though DVB-T is likely to remain around for quite a while.

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Feedback | Feedback
Wednesday 12 October 2011 2:03PM

Briantist: Digital UK's postcode checker is now showing 'COM Mux FEC Change' on various muxes at various sites, over the next couple of months. Hovering over ArqB for The Wrekin shows a change from 64QAM 2/3 to 64QAM 3/4.

It's possible that this will be accompanied by an increase in the guard interval, aiming to improve coverage by turning co-channel interference into SFN; I notice that Hannington and Crystal Palace now show all three COM muxes going to 64QAM 3/4 at switchover, and CP COMs are co-channel with Rowridge. The net capacity is likely to be the same, if that's the case.

64QAM 3/4 8K 1/8 has a fraction more capacity - 24.88 Mbps - than 64QAM 2/3 8K 1/32 (24.13 Mbps).

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Divis (Northern Ireland) transmitter
Wednesday 12 October 2011 2:24PM

Peter Henderson: Digital UK did publish a brochure stating 10th and 24th October 2012 on their website, but the site was reverted to an older version. There could still be an announcement in the next week or so, much longer and it's probably further delayed.

Black Mountain is the old IBA VHF TV mast - Divis was the BBC mast - and has plenty of aperture for a high-power antenna. Channel 5 analogue transmits at 50 kW, apparently from a skew-fire array at the top of the 228 metre mast. A cantilever could perhaps be added if required, or RT could take over the C5 array, depending on how flexible it is and whether it might be needed for MUX 7, 8, 9.

It may be that the new Divis mast wasn't designed to take the weight of the RT mux antenna in addition to everything else, assuming that for whatever reason the PSB or COM main antennas can't be used.

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Andrew Clinton: The only engineering work was this morning, bringing the SDN multiplex up to full power and on the main broadcast antenna. This shouldn't have had any effect on reception of HD channels, unless you were close to having too much signal before, and the additional power on the SDN multiplex has now pushed it over the edge.

See Freeview signals: too much of a good thing is bad for you | ukfree.tv - independent free digital TV advice for more.

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P Smith: Sudbury's next stage is to move ArqB - which carries Yesterday - to C63 on 16 November, to get out of the way of Tacolneston's high-power digital transmissions on C50.

The final channels and power levels will be reached on 27 June 2012, after Dover has stopped using them - the Meridian East region completes switchover on this date.

Digital UK's predictor suggests that your reception of ArqB should be improved when it moves to C63 in mid-November.

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Ian: Sky would waive the fees because they don't want a full investigation into their subscription business. Sky take most of the money off the top of the regular entertainment pack subscriptions and use it to subsidise the sports and movie packages.

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Ian: Sorry, I misread the headline, assuming something that I shouldn't have, that Sky had decided to do so.

The fact is, Sky charge the channels a 'Platform Contribution Charge' which has nothing to do with the costs incurred - it is weighted to the share of viewing. This is actually the majority of the money, the BBC being charged £9.89m overall, £4.78m for BBC One alone. The platform is very well-developed and this charge should be entirely dropped, for all channels.

The actual EPG charges per EPG slot are outrageous too, costing approximately one average worker's salary per slot. I can't believe that it takes anything like that much to manage the flow of EPG data, particularly for the BBC which is very well set up for metadata, since they feed Freeview, Freesat and cable services in addition to Sky.

The regionalization component is something like £2-3m - I couldn't figure out exactly what rules Sky were applying.

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