All posts by Dave Lindsay
Below are all of Dave Lindsay's postings, with the most recent are at the bottom of the page.
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, RTÉ 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. steve: I expect that there will be "some" people affected who use the Emley Moor transmitter. 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:
https://at800.tv/find-out-more/testing/
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. 
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.
-----
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. 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. 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. 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. michael: I'm surprised you have got it so reliably.
We don't know for certain, but it would seem sensible to think is that Emley Moor doesn't put out as much signal in a westerly direction as other directions, as it will be being beamed into the Pennines, or else be available, possibly intermittently on the "wrong" side of the Pennines.
Parbold relay is co-channel with Emley's PSBs, albeit vertically polarised. Kate Rogers: The broadcast channel (frequency) of PSB2 which carries ITV, C4, C5 and others changed at the Ivybridge transmitter.
If your set has manual tuning on, try scanning UHF channel 40. Sid: That's good...that they are starting at the top. Robin Mutch: I do not understand why you are so quick to dismiss the possibility of it being trees. The fact that not all channels are affected is typical of the effects of trees on reception.
The point about the ground dropping was taken from the Megalithia terrain plot. Of course it only samples the ground height at intervals so it may not be entirely representative of your situation. Steve Lyons: When everyone else can which is when the BBC Red Button data is carried on both the standard definition multiplex (PSB1) and the high definition one (PSB3) at the same time. Robin Mutch: It may appear to be the opposite which how too much signal appears because its action is to overwhelm the tuner thereby making any readings unreliable.
If you have three TVs fed from one aerial with a distribution amplifier, perhaps it is overloading the amplifier which is like turning up the sound on a hifi beyond that which the speakers can cope, which means that the sound becomes distorted. Harry C: Yes it's a coincidence!
The Waltham transmitter is 13 miles away which is much further than mobile phone signals work across.
According to 
'Sitefinder' Mobile Phone Base Station Database there is a Vodafone base station on Manor Drive where there is a mobile phone tower shown on Streetview. Sitefinder may not be up-to-date.
Has a building gone up between that base station and the area you have difficulty getting a signal in? Harry C: At the same location, Sitefinder indicates there is an O2 3G base station. The O2 coverage checker indicates base stations and this one is shown, which may be an indication that it is still there.
The base station is at the front of Soar Valley Timber. Zoe: If your set has a manual tuning option then try a manual scan of UHF channel 49, which is that for the services you are now missing. Yaz: All the aerials I can see on Streetview are pointing roughly due south, which is to Bilsdale. COM4 (SDN, the multiplex which carries 5USA and others) is on C43 from Bilsdale and C50 from Pontop Pike which is the opposite direction.
If it was tuned not to the transmitter to which the aerial faces then this explains why reception has changed.
Bring up the signal strength screen on the TV and see which it is tuned to.
Pontop Pike's channels are in roughly the top half of the band and Bilsdale's are in the bottom half, so unplugging the aerial after the first 50% of the scan should help miss out Pontop Pike. Zoe: Do you have any other box, notably a Sky box, which could be interfering with the C49 signal?
If you do try feeding the incoming aerial lead directly into your TV and then perform a manual scan of C49 again. Annie: Perhaps the trees that are in the signal path (i.e. between you and the transmitter) coming into leaf.
There are an awful lot of them on the other side of Manchester Road. I see on Streetview that a few houses have their aerials on high poles, presumably in an effort to 'see' over the trees. Jeff Harris: Interference from a noisy electrical appliance is always a possibility. The Sky box of a neighbour won't interfere, certainly not in the way which one might if you have it connected into your aerial lead.
If you have an amplifier that was installed in order to pick up the digital signals before switchover it might be worth removing it. Yaz: Try unplugging just after C46 which is the highest channel from Bilsdale. Perhaps it may appear frozen but give it a while. Go away and make a cup of tea.
See which the TV is tuned to. View the signal strength screen whilst tuned to one service from each multiplex:
PSB1 - BBC One | B=C26 | PP=C58
PSB2 - ITV | B=C29 | PP=C54
PSB3 - BBC One HD | B=C23 | PP=C49
COM4 - ITV3 | B=C43 | PP=C50
COM5 - Pick TV | B=C46 | PP=C59
COM6 - Film4 | B=C40 | PP=C55
B=Bilsdale; PP=Pontop Pike
How do the strengths compare on the channels? When you do a manual tune on C43 but do not press the button to scan the channel, does it give an indication of strength and quality and if so, what is it? You will have to give it five or ten seconds to settle.
If you haven't had your aerial replaced from the days of four channel analogue then perhaps you could do with it doing. The analogue channels from Bilsdale were in the first third of the band of frequencies used for TV (Group A). PSB channels are in Group A but COM channels are in the middle third, Group B, so your aerial may be less sensitive to 'hearing' them (if it's a Group A one). Bill Morrison: Evidently they are not tuned in then, or at least the HD services are not on their proper logical channel numbers.
Try and manual scan on UHF channel 54. If there is an option for mode with respect to the manual scan make sure it is set to DVB-T2 (high-definition signal type) rather than DVB-T (standard definition signal type).
A TV which is labelled as "HD Ready" does not have a DVB-T2 tuner in-built and will therefore require a separate receiver to show HD pictures off the air. Bednortan: You may be lucky to receive the COM channels reliably from Wenvoe.
The Public Service (PSB) channels have the same coverage as the former four-channel analogue network. The Commercial (COM) ones fit in around where they can, using channels (frequencies) that are reused by transmitters in closer proximity than the PSBs, hence they are more likely to be limited by interference - which means unable to receive due to interference from a co-channel transmitter.
The Van Terrace relay transmitter is co-channel with Wenvoe's COMs, both horizontally polarised.
"-3dB" means 3dB less than the power of the PSBs, i.e. half power.
You might find that repositioning the aerial might work, the objective being to find a spot where the signal from Wenvoe is good but which the interference from Van Terrace isn't so. That said, because you are in an area that doesn't have great reception from Wenvoe you may find that all or some COM channels are hit and miss at times. yaz: The fact that you are receiving the COM channels from Bilsdale on the TV tends to suggest that the aerial is not an issue, so I would of course suggest that it's not necessary.
I'm not sure what else to suggest. Perhaps one of the professionals will be along in bit with some suggestions. CricFan: Because there is no DAB signal available.
The "digital radio stations" that appear on your TV are carried via the "Freeview" signal rather than a DAB signal. David Shaw: There are few possibilities:
You may be able to wipe what's already stored, for example by running the scan through with the aerial unplugged. Then manually tune the five SD muxes (and one HD mux, if applicable).
Or you may be able to have the aerial lead unplugged during scanning of Sutton Coldfield's channels. The scan runs channels 21 to 69, so if yours only gives a percentage progresss you can estimate the channels. Roy: No, it's not a 4G problem because there are no 4G signals operating in the 800MHz band in your part of the world.
Which channels is it? The Millburn Muir transmitter only carries Public Service (PSB) channels, so if it's to do with the Commercial (COM) channels then you must be receiving it from elsewhere and so reception may be patchy or non-existant.
PSB services are shown above.
Further advice on reply. MikeB: The "next week" referred to was that starting 6th June!
Roy: If it is the COM channels you are picking up then perhaps you are getting them from Rosneath. In which case an aerial pointing to it "may" bring them in reliably.
As I say, further advice can be given with knowledge of the channels affected. Also your location would be useful, being more specific than the town, this being to check the likely reception possibilities as they are likely to vary across Dumbarton, due to the terrain. A postcode is best, or one of a nearby address such as a shop. MikeB: That should be week starting 6th May. John Martin: I presume you are using a HDMI connection if it is a separate receiver. mike shaw: "The one on the Wirral" is Storeton and it only carries PSB (Public Service) channels, hence the channels you are having difficulty with are the COM (Commercial) ones which you are probably receiving from Winter Hill.
The general idea for Storeton Wales transmitter is that it and Winter Hill are roughly in line and so a single aerial should work for both.
Perhaps your aerial could do with turning a little clockwise, nearer the direction of Winter Hill. mazbar: Whilst you are correct, Mike Shaw lives on the Welsh side of the transmitter and therefore not able to receive the COMs from it, even if he wanted.
The Storeton transmitter relays the PSB channels from Moel-y-Parc. It broadcasts them directionally, towards Wales, using horizontal polarisation so as to match that of Winter Hill. It also broadcasts the PSB and COM channels as a relay of Winter Hill, these being vertically polarised and radiated in the opposite direction to the Welsh PSBs. For that reason Mike Shaw will not be able to receive them and will probably have to use Winter Hill for them. mike shaw: From your location, Storeton is on a bearing of 19 degrees and Winter Hill 38 degrees. Hence your objective is to have your aerial pointing somewhere between the two, which allows you to receive from both transmitting stations, if this is possible. For this reason aerials of different houses may be pointing in ever so slightly different directions. m botchin: Without knowledge of your location, preferably in the form of postcode or nearby postcode such as that of a shop, it isn't possible to give guidance on expected reception possibilities.
However, the Commercial (COM) channels which cary Russia Today, Al Jazeera and others are generally the first ones to show poor reception. Therefore, bearing in mind I have no idea as to the transmitter you are using, either you have too much signal, as suggested by Brian, or your TV is tuned not to the transmitter to which your aerial faces for BBC, at least. 
05:16
Freeview signals: too much of a good thing is bad for you | Digital switchover | ukfree.tv - 10 years of independent, free digital TV advice 
DVB-T2 - Wikipedia, the free encyclopedia 
