All posts by Mike Dimmick
Below are all of Mike Dimmick's postings, with the most recent are at the bottom of the page.
MarkR, stevea: I had to resort to watching the F1 on my laptop as both analogue and digital were poor. I think it was down to atmospherics - it was quite foggy on Sunday morning - rather than any work on the transmitter. (I wouldn't want to be up a mast at 6am on a Sunday, would you?)
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Briantist: Chelmsford C5 is a bit of an exception as it belonged more to the London region than to Sudbury, but it went off at Sudbury DSO 2. Still, it *was* an exception.
According to the last timetable published by Ofcom, Channel 5 analogue must switch off by 31 December 2012, but it also still says that for the UTV region as a whole.
I think it's unlikely that analogue C5 from Black Mountain would be switched off before the DSO date.
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Algernon Black: Because the switchover programme is still in progress, a later change at another transmitter can affect some viewers. If they'd switched everything over in one go, this wouldn't have happened - and you'd never have noticed.
Most likely you're in the south or south-east of the coverage area, near High Wycombe, Assendon or Chisbury. Those three transmitters' PSB multiplexes will clash with Oxford's COM multiplexes. The commercial multiplexes are not required to meet any specific level of coverage and certainly not to match the PSB multiplexes, which are required to substantially match analogue coverage.
'Variable' reception in Digital UK's postcode checker does not necessarily mean variable results. It means that using their aerial model, the percentage of locations that should, on average, have reliable performance 99% of the time, is below 70%. It means siting an aerial to get reliable results will be more difficult than if the 'good' standard was met. The aerial model is quite pessimistic, compared to real aerials, regarding rejection of signals from other directions and from the other polarization (those relays will transmit vertically-polarized signals and Oxford uses horizontal polarization).
High Wycombe and Chisbury already use C55/C59/C62 for their analogue transmissions, but a digital service does do more damage to another digital service than an analogue one does. Assendon uses C55 now and will start using C59 and C62 at switchover.
If you do find you are affected, you may be able to fix the problem by rotating the aerial slightly towards or away from the interfering transmitter - real aerials have peaks and troughs in their 'polar response' - how much signal is picked up from different directions - and you may be able to drop the interfering signals into a trough in the response.
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barry: Most likely power to the distribution amplifier failed - perhaps a blown fuse or tripped circuit-breaker? Report it to the landlord or management agent.
At that location, I would expect an indoor aerial to be pretty reliable.
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For reference, VLV is Voice of the Listener and Viewer (VLV)- the campaign for Public Service Broadcasting. and the event was titled "UK Programme Production - Securing its Future".
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Chris Onion: At that postcode, there is a poor prediction for the ArqB multiplex - which carries Sky Sports 1 and 2 - from Waltham. The prediction for Sutton Coldfield is very good.
Digital UK never explain their predictions in detail, but there are a number of relays in the vicinity (Bolehill, Repton, Winshill) that transmit on C57. Levels of signal both from the wanted transmitter and from interfering transmitters do vary over time and not necessarily in line with each other.
If your aerial points south-east to Waltham, you may get better results by pointing south-west to Sutton Coldfield. You would still get East Midlands BBC One and ITV1 from the Derby relay - providing East Midlands service to people better covered by Sutton Coldfield is the reason that it exists.
In both cases you should check that the box has actually tuned in services from the wanted transmitter. See Digital Region Overlap for more information.
Given that the prediction from Sutton Coldfield is 99% across the board, and that you say it was OK before switchover, chances are that if there is a signal level problem, it's too much rather than too little.
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Briantist: Yes, but that's not yet in the Digital UK postcode checker. If the conclusion is that the interference from those relays doesn't significantly affect that many Oxford viewers, chances are that Oxford and those relays will be moved to the same channels.
Ofcom's latest 'Table of Digital Stations' (version 5) now has High Wycombe and Assendon BBC B, and Chisbury BBC A, using C50 rather than C62 from their DSO dates. So perhaps that isn't the source of interference, or not the whole story.
The next nearest transmitter using the same channels is Midhurst, and of course this is a relatively high-power main transmitter using horizontal polarization. The variable reception prediction may just reflect lift conditions. At present C55 is an analogue channel at Midhurst, C59 and C62 are low-power digital multiplexes.
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trevorjharris: The point is not that Sky viewers are having to pay for what others get free, it is that *Sky is charging the broadcasters for what other platforms give away*.
Each Sky viewer costs the broadcasters money, money that they do *not* recoup from subscription revenue. Free-to-air channels don't receive any payments from Sky's subscriptions, nor do 'free-to-view' (encrypted, but available to anyone with a viewing card even without an active subscription). Only the channels actually listed in the Entertainment Pack or Entertainment Pack Extra do. Even for them, Sky's Platform Contribution Charges will often exceed the revenue earned.
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Kate: Sky charge the BBC and therefore the 60% of licence-fee payers who DON'T use Sky a 'Platform Contribution Charge' that Sky use to subsidise their boxes. This charge is related to the percentage of viewing of each channel. It is in no way fair, reasonable or non-discriminatory and should be eliminated.
The charges for appearing in the EPG should be related only to the costs directly incurred in running the EPG, and should be shared fairly between all channels, the PSBs should not be charged more than other channels as they are now. I do not believe that it costs an average worker's salary to maintain an EPG slot, even allowing for other costs of employment - Sky should be forced to account for the actual costs incurred.
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Tuesday 18 October 2011 5:33PM
guy: A Freesat box will give you BBC, ITV, C4 and C5 satellite services with no subscription. You can compare the channels available on Freeview (TV through an aerial), Freesat (no subscription, free choice of box), and Freesat-from-Sky (Sky boxes only, requires £££ for recording and time-shifting) at Compare Freeview and Freesat TV | ukfree.tv - independent free digital TV advice .