All posts by Dave Lindsay
Below are all of Dave Lindsay's postings, with the most recent are at the bottom of the page.
Andy, otford: You've posted on the page for the Otford transmitter. If your aerial is directed at it, then it's a wonder you ever received Dave anyway because it doesn't broadcast it. In which case you need to look at getting an aerial on Crystal Palace.
If your aerial points to Crystal Palace, then I suggest that it could be the Inversion effect in play. By retuning you have shot yourself in the foot because you will now not know when the effect has lifted and you will need to keep retuning until it comes back. Had you left it then you would have simply been able to select Dave.
For Dave you need to manually tune to UHF channel 22, if your receiver allows.
Otford transmitter is north east from you on Otford Mount. Aerials are vertical.
Crystal Palace is west north west from you and aerials are horizontal.
See this picture for a photo of aerials polarised horizontally and vertically:
http://farm5.static.flick….gif
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Syd Wall: There were some retunes caused by changes made at a number of transmitter sites in the early hours of yesterday morning, but these were further east and affected some of Anglia and South East areas.
If you can get the message to go away (by pressing "OK" or similar), then you can probably ignore it.
I wonder if your receiver has, in addition to your native transmitter, found and stored signals from Sandy Heath which is an Anglia transmitter. Of the Anglia region, it was the Sudbury transmitter that was affected by the retune (not Sandy Heath). I wonder if the message you are seeing is one which was broadcast over the air from all Anglia transmitters, simply because it is not possible to have the message broadcast only from Sudbury (because perhaps they all have to carry the same message, as it were).
I'm not too familiar with how these things work; just a technical bod giving you my thoughts of what I would see as a possibility. If it continues, then you will have to look at a solution. The worst case solution is obviously to carry out a full retune, but I wouldn't do it at this stage. If it does continue, something to try before doing a full retune might be to add new services (or similar) if your receiver has such a function.
As I say, these are possibilities if the message doesn't go away. But what I can say for certain is that there were definately no changes to Lark Stone and Sutton Coldfield transmitters that would require a retune.
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Derek: A number of people have reported difficulty with signals from Crystal Palace and it is believed that this was due to the inversion effect, so there is probably nothing you can do.
Assuming no local obstructions like trees and buildings, you appear to have line of sight with the transmitter. Where that is the case, at 18 miles from a transmitter of the power of Crystal Palace, there should be no need for a high-gain aerial.
See this link for a plot of the terrain from you to CP:
Terrain between ( m a.g.l.) and (antenna m a.g.l.) - Optimising UK DTT Freeview and Radio aerial location
Follow the link below the trace for a map with a line joining the two points (which may not be exact).
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IPG Derwent: This is correct.
Unfortunately the UK now has a two-tier terrestrial transmitter network. It is likely that viewers will wish to receive from full service transmitters where possible.
Leamington Spa transmitter only carries the Public Service channels because the Commercial broadcasters don't wish to invest in it.
Looking on Streetview, there are buildings on the other side of Coventry Road receiving from Sutton Coldfield, and these are as high as yours, so it may be a possibility.
Obstructions such as buildings and trees can cause difficulty with reception. However, your chances could be increased by virtue of the fact that you are in a two-storey building.
Some aerials, particularly those installed in the days of four-channel analogue, only work with certain bands of frequencies (those frequencies that the designated transmitter uses/used). Should this be the case then a Leamington Spa aerial won't be suitable for Sutton Coldfield. If it is a wideband, then it will be suitable.
Recepion from Lark Stone would appear extremely unlikely, according to the Digital UK predictor.
I suppose that it will probably be down to your landlord to do something.
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Adrian Sankton: That is correct; there were no changes to the transmission power.
The S1 antenna was to protect against interference with transmitters in Kent until they switched over. This is because they used the same frequencies pre-switchover.
It affected the signal in that general direction, focusing it lower down to the horizon so as to curtail its propagation (in that direction).
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Tony Adams: During the automatic tuning scan, it looks at UHF channels (equivalent to frequencies) from 21 to 69.
Crystal Palace (London) uses channels in the 20s and number 30. Bluebell Hill uses channels ranging from 39 to 54.
You can therefore avoid Crystal Palace by unplugging the aerial for the first 30% of the scan. However, if the Anglia transmitters you are picking up are Rouncefall and Sudbury (these operate using the same frequencies), then you can't avoid them without missing out some of Bluebell Hill's.
Rouncefall/Sudbury uses 44, 41 and 47 for BBC, ITV1 and HD respectively.
If you can wipe the channel memory altogether and manually tune, then do that.
For Bluebell Hill you need to tune to:
46, 43, 40 (HD), 45, 39, 54
If you can't wipe the memory, perhaps by starting the automatic tuning scan with the aerial unplugged and maybe stopping it just after it has started, the objective being to "blank" what's stored. Or maybe run the automatic tuning scan through fully with the aerial unplugged.
If you have it all tuned in but wrong (e.g. you have BBC London), then it may well have put Bluebell Hill in the 800s. Therefore, when you manually tune to Bluebell, it may do nothing because as far as it is concerned, it has tuned to Bluebell.
Failing that, run the scan with the aerial unplugged up to 55%. This should pick up C54 from Bluebell which is COM6 (Yesterday etc) ONLY.
Refer here for services by multiplex (those with a bullet in the "E"/England column apply):
DMOL Post-DSO Multiplex Channel Allocations
If at this point you only have those in COM6, then manually tune the other four (or five if you have a HD receiver).
The numbers I gave above are in order of multiplex.
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Linda Taverner: When you say "all are the same" if you are saying that all flats have no signal, then this clearly indicates a problem with the aerial system. You probably need to raise this with your landlord.
There was a retune required (from) yesterday for Heathfield for ITV3 and some other services. This only affected a small proportion of services and did not affect BBC, ITV1, Channel 4, Channel 5 (and quite a few others were unaffected).
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Mike Gordon: I think that this might be the inversion effect which is caused by the weather causing signals from another transmitter to reach your location.
There was definately no retune for Crystal Palace and there is not one sceduled this year or next, so under such circumstances it is NOT advised to carry out a retune as all this can do is cause the services to be lost from the receiver's memory.
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Mrs Thompson: Unfortunately Henley-on-Thames transmitter does not carry the Commercial channels and is not likely to.
The Commercial broadcasters cover 90% of the population by transmitting from 81 of the largest sites (by viewer population). There are over 1,000 small "filler-in" relay transmitters like Henley and for them to include these would roughly double their cost of transmission whilst only adding about 8.5% of the population to their potential viewer-bases.
As they operate to generate profit by selling advertising which they show to viewers, they don't consider it worth it. What you get from Henley are the Public Service channels only. The Commercial broadcasters have no "Public Service" obligation.
The difficulty with receiving from Crystal Palace in your area is due to the fact that it is in a valley. This is why the Henley transmitter was installed.
In some areas it "may" be possible to receive from Crystal Palace, but this could vary house by house. And in any case, a substantial aerial may be needed.
I went along Reading Road on Streetview and most aerials were on Henley. A few were on Crystal Palace.
The two transmitters are in almost the same direct, but it is easy to tell which an aerial is pointing to as Henley's are vertical and Crystal Palace's are horizontal. See this picture:
http://farm5.static.flick….gif
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Thursday 28 June 2012 12:12AM
IJB97: Unplug the aerial for the first 30% of the automatic tuning scan to miss out signals from Crystal Palace.