All posts by Dave Lindsay
Below are all of Dave Lindsay's postings, with the most recent are at the bottom of the page.
J.L.Townsend: With digital television, multiple services are carried on the same signal (and therefore same frequency). Each signal is known as a multiplex (or mux). Each former analogue service occupied the space of one digital mux.
There are six muxes, three Public Service (PSB) ones and three Commercial (COM) ones. For a list of service by multiplex, see:
DTG :: DTT Services by Multiplex
All BBC standard definition TV and radio services are carried on PSB1.
There have been no additions to the Greenhill transmitter. The COM channels have choosen not to broadcast from the smaller transmitters and are never likely to do so. See here for an explanation:
Londonderry (Northern Ireland) digital TV transmitter | ukfree.tv - 10 years of independent, free digital TV advice
Assuming that the new channels you are referring to are Commercial ones then, based on the Digital UK predictor, the only conceivable transmitter that may give you these is Preseli. On the basis that the COMs are being received from that station, perhaps PSB1 is also tuned to Preseli rather than Greenhill.
Bring up the signal strength screen whilst on BBC One. Receivers usually give the UHF channel (or frequency) that they are tuned to. For Greenhill it will say C24 (498.0MHz) and for Preseli it will be C43 (650.2MHz).
As Greenhill's channels are within the first third of the band and Preseli's are in the mid-third, when you run the automatic tuning scan unplug it when it gets to 30%, or past C30 if it gives UHF channel numbers as it scans.
Because the Commercial broadcasters have not been mandated to provide the same coverage as the Public Service ones there are some viewers who will be without. Some viewers may be able to receive the full service with a different aerial and in some cases this will be from an alternative transmitter. In your case, you "may" be able to receive all channels from Preseli.
I emphasise "may" because there is no given and predictors are just a rough guide; the only way is to have an installer investigate.
Looking on Google Streetview (photos taken August 2009) I can see quite a few aerials on Preseli. With this in mind, if you are using Preseli then perhaps your TV has tuned to Greenhill instead. If so then unplug the aerial for the first 30% of the scan.
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Matthew Wills: BBC HD is now BBC Two HD.
All BBC services, including HD ones, are available from all transmitters. The BBC is a Public Service broadcaster.
The other channels, which are the Commercial (COM) ones (capital "C"), are not ever likely to broadcast from the Poole relay transmitter because they don't consider it worth their while. See:
Londonderry (Northern Ireland) digital TV transmitter | ukfree.tv - 10 years of independent, free digital TV advice
The Commercial broadcasters have no "Public Service" obligation.
It may be worth investigating whether you might be able to receive all channels from Rowridge or Mendip.
As you may know, Mendip broadcasts BBC One West and ITV West. You could use Mendip as your main transmitter, feeding it into your PVR and TV. Then have a separate set-top box for Poole which you use when regional programming is being broadcast.
Unfortunately, Mendip's channels (frequencies) are such that you would not be able to combine the feed from an aerial on it with that of your Poole aerial.
Or perhaps you can receive from another of Rowridge's relays (in place of Poole) which would be able to be combined with Mendip's COMs to give you the full service.
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Matthew Wills: Luscome Valley transmitter wouldn't be able to be combined with Mendip's COMs, so perhaps there are none that will that you can receive.
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Alex Theo: One thing you may have to contend with is the Van Terrace transmitter being co-channel (same frequencies) with Wenvoe's COMs. There may be too much interference, or there may be some object that helps block the unwanted signals. That said, Van Terrace is vertically polarised and Wenvoe is horizontally polarised.
The COM channels are those that you don't get from Mynydd Machen.
Have any of your neighbours got Wenvoe aerials? Remember that the fact that they have does not necessarily mean that they can receive all channels (because either the COMs are too weak and/or Van Terrace is being picked up too much).
I'm not sure I can add anything further as I'm not a professional. It's just something to be mindful of. There appears to be no other full-service transmitter that you may be able to pick-up from.
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barrie wreford: Can you not use the Risca relay, or even Wenvoe which would probably give you the full service?
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Alex Theo: I doubt you will receive from Mendip (although, as I say, I'm not a professional). See this terrain plot from you to Mendip:
Terrain between ( m a.g.l.) and (antenna m a.g.l.) - Optimising UK DTT Freeview and Radio aerial location
The high ground about 2 miles away from you is Graig Llanishen and it is about 200m above your ground level. A look at the predicted coverage map on this site suggests that up until that point reception from Mendip may be possible.
The gentleman in Bedwas lives on the north side of the valley. That is the side of the valley that faces Mendip, even if it can't quite be 'seen' at his location.
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Alex Theo: I should point out that the coverage maps are a rough guide and should not be interpretted as being indications of where reception will definately or will not definately be possible.
They indicate where the signal is expected to be at a particular level and a particular height above ground.
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Alex Theo: My apologies. Van Terrace is horizontally polarised as the photo of it shows (the two horizontally polarised logs at the top):
mb21 - The Transmission Gallery
Digital UK Coverage Checker also says that it is horizontally polarised.
It's certainly the case that at Bedwas, Van Terrace is on a close bearing to Wenvoe.
However, this terrain plot from you to Van Terrace suggests that the ground around where the interchange is is perhaps 30m or more above where your aerial will be:
Terrain between ( m a.g.l.) and (antenna m a.g.l.) - Optimising UK DTT Freeview and Radio aerial location
Also note Van Terrace's "dickie bow" shaped radiation pattern, so the full force of the 2W isn't being beamed in your direction.
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Jenny Milborrow: This page does not say that there is no problem; it states that the BBC and Digital UK have not reported a problem.
There is a link "Click to recheck" which goes to this page:
Radio & Television Service
On there it says off air from 14:08 today.
This website is independent of the broadcasters. The information it gives is taken from official sources.
It works by checking these sources. Only at the time it checks will it ever be updated. That is, it 'looks' at these sources. There are over 1,000 transmitters in the UK so that is a lot of automatic checking. The more often it does this the more load it puts on the server and the more likely those running the websites that it is checking are to block such access.
Hence it may take some time for the information on here to be updated which is why the "Click to recheck" link is provided.
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Sunday 7 April 2013 7:13PM
Andrew: That would suggest something common to the two: perhaps a power failure again.
Putting the transmitter's postcode, SK13 7QJ, into
Electricity North West
says "No current fault detected" at the moment.