All posts by Dave Lindsay
Below are all of Dave Lindsay's postings, with the most recent are at the bottom of the page.
David Shaw: If you have a Sky box connected into your aerial system then that could perhaps be a factor.
Confirm that it is tuned to Waltham on UHF channel 49, by viewing the signal strength screen whilst on BBC One. Other possibilities may be the Derby relay transmitter on C48 and Sutton Coldfield on C43.
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steve: I expect that there will be "some" people affected who use the Emley Moor transmitter.
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steve: Because it won't be all who are affected.
Generally speaking, those potentially affected will be in small pockets where the 4G signal is strong and, relatively speaking, the TV signal is weak. This will tend to be those who are in close proximity to a 4G base station.
The issue will not be the presence of signals in the 800MHz per se, but where 4G signals are at much greater level than TV signals.
There are similarities with RF signals and light so consider what you know about the latter. Think of walking alongside a road at night. When car headlights come towards you they are bright and prevent you from seeing the darker surroundings that would otherwise be visible. The headlights are like the 4G signal in cases where TV reception may be affected.
The strength of a signal drops off rapidly as distance from a transmitter increases so those affected will usually be in close proximity to base stations.
There are a whole raft of other factors that act as fors and againsts as to the likelihood of an issue. These include the closeness of the frequencies of the wanted (TV) signal and the unwanted (4G) signal and the degree which the aerial is sensitive to each.
A wideband aerial, which is not necessary for TV from Emley Moor, is likely to be more sensitive on the 800MHz frequencies than one that isn't wideband, for example.
All in all there are so many variables that it is practically impossible to calculate whether any one individual is likely to be affected and with any degree of certainty.
If at800, which is the organisation sending out postcards, does not know for certain which viewers "will" be affected, who do you think might be more certain? If such people exist why do you think that at800 did not consult with them?
at800 have carried out a number of tests and it appears that a small minority will be likely to be affected:
Testing | at800
The newspapers are quick to report that a particular proportion of viewers are expected to be affected. They quote statistics such as more people will be affected who use Crystal Palace than any other transmitter. It is also a fact that more people use Crystal Palace than any other transmitter!
The question most people are interested in is one of whether they will be affected. That has so many unknowns that it is impossible to say. The newspapers don't bother to mention this though. A crystal ball would seem to be the only way one might get to know whether TV reception will be affected.
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steve: Only over the last few months has Digital Mobile Spectrum Limited ("at800") conducted some tests to get a more accurate handle on the likelihood of issues. This can only ever be a probability based on a statistical sample (i.e. a test).
The only "con" on the population in general can be via information published by the media.
When the media asked - before tests were carried out - how many homes might be affected then the only possible answers that the powers that be could give were:
1. the estimated figure having not carried out a real-world test, or;
2. "we don't have a figure".
Can you imagine how it would have been spun in the news if they had answered with the latter? The newspapers wouldn't have been likely not to run a story if that answer were given. And so they would have publicised the fact that there was no official estimate.
Therefore the only likely out was as happened which is that the best guess at the time was used. It turns out that, following the tests, less homes will be affected, so the estimated figure is now lower than it was.
Can you imagine how it would look if the found that the issue is likely to affect far more people than first thought? The figure would have to have been increased which wouldn't look good.
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If you are using a communal aerial system then it is the responsibility of your landlord, or whatever party maintains the system, to install any necessary filter. It could potentially already be fitted with a filter anyway.
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Briantist: I mentioned it as it would seem logical to suggest it because a wideband aerial may have more gain on C61 to C69 than an equivalent Group B aerial. Perhaps in practice any difference is neglible and there are far more bigger factors in play such as field strength.
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Tim Kaye: I suggest that, if possible, you use Heathfield instead.
Hastings' COM channels (which carry ITV3, Pick TV, Film4, ITV4, Dave and others) are co-channel (same frequencies) with the Public Service (PSB) channels of the Eastbourne relay transmitter which is on the top of South Cliff Tower.
Unfortunately the COM channels are only available from the larger transmitters and the channels they are allocated are often re-used in closer proximity than the PSB channels. For this reason not everyone can pick them up reliably, or at all.
In your general area it may be beneficial to change to using Heathfield in order to receive all channels.
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Alan Horsley: I suggest that this is likely to be some localised electrical interference. See here:
How do I know if the 4G broadband will overload my Freeview? | 4G-at-800 | ukfree.tv - 10 years of independent, free digital TV advice
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steve: The terrain plot suggests that you may have line-of-sight to the top of the Emley Moor tower, not taking into account anything on the ground. I noticed the high-rise flats that will be in the way for some in your general area.
With this in mind perhaps the tall aerial poles are not because the signal is weak but because those buildings reflect the signals (because they are so strong). In the days of analogue this would have resulted in ghosting, but with digital it isn't really an issue.
If this is a communal aerial which feeds multiple flats then it will likely have an amplifier (booster) because splitting the signal will result in less signal to each output. Therefore the objective of the amplifier is to counteract the loss due to splitting it.
As I say, if it's a communal system it may already be filtered or the party responsible may have to arrange for a filter to be fitted. It will not require each tennant to use there own filter as the filter, in a communal system, should be fitted at the aerial end.
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michael : I should think that the answer is to do with the fact that you don't have line-of-sight due to the Pennines being in the way!
The high ground over which you are receiving is likely to form a mist at night, which might be the cause.
Refer to the terrain plot:
Terrain between ( m a.g.l.) and (antenna m a.g.l.) - Optimising UK DTT Freeview and Radio aerial location
How do you fair in autumn, winter and spring? I think that it's quite likely to be misty up there quite a bit of the time.
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Saturday 15 June 2013 9:39AM
Peter: Putting a lead in from the Freeview box's aerial out to the TV's aerial in is only required so that Freeview can be received by the TV. In this case the box is being used so there is no need for making that connection (unless the TV has a Freeview tuner in-built and it is to be utilised).
According to the above, RT One will appear on logical channel number 51, if it is the NI Mux that is being used. It might be worth looking in the 800s just incase it has been put there.
Is it a single aerial that your neighbour has pointing east north eastwards?
If the AGR-DVBT2 box allows, try a manual tune on UHF channel 39. If there is a setting on the manual tune screen for mode, as in DVB-T or DVB-T2 then the latter must be selected.