All posts by Dave Lindsay
Below are all of Dave Lindsay's postings, with the most recent are at the bottom of the page.
Desmond kerr: This sounds like interference, which a battery-powered AM radio might locate. It could potentially be in a neighbouring property.
Things like the motor in the three-way port valve in your central heating/hot water system could be a culprit, for example.
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Chris Shaw: After switchover Rowridge began to transmit vertically, having previously only been horizontally polarised. COM4-6 are lower power horizontally so as to fit in with Stockland Hill and Crystal Palace whose COMs are co-channel. This is not unlike many other transmitters which carry all six main multiplexes, where the COMs are often at half-power to the PSBs, the latter having been allocated the better channels as far interference from other stations which use the same channels.
Now when COM7 (and COM8) was designed, the objective was to serve as many as possible across the country at least cost. Presumably the decision was taken that the addition of vertical polarisation would not be worth it think of Rowridge HP and Rowridge VP as if they were different transmitters.
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Jacqueline Macmillan: Well, if there are others, and this isn't a shared (communal) aerial system, then logically the fault is likely to lie with the transmitter.
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Jacqueline MacMilkan: I doubt there is anything to flag/report this is a main transmitter and will therefore be remotely monitored.
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Lesley Crooks: Well, if you and the neighbours you're referring to are using a communal aerial system then that would seem to point firmly at it. Thus, you need to raise the issue with your landlord, or whatever party maintains the aerial system.
It is a little odd that it keeps going on and off. This could be indicative of the power to the system being turned on and off, maybe by accident.
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IanR: Is this the problem?:
http://www.digitaluk.co.u….pdf
The London Live multiplex has a negative offset, C29-, meaning that its frequency is a bit below the centre of C29. However, COM6 from Crystal Palace also has a negative offset, but the other standard definition multiplexes don't.
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IanR: My assertion that C29 has a negative offset comes from Digital UK:
Coverage Checker - Detailed View
As for others not receiving C29, one reason is that they are using a communal aerial system which needs adjustment to allow the new channel through. Another reason is that the transmission power is lower than the other channels, so those in less than favourable areas "may" require extra power in order to receive. It is in now way "low", though, at 20kW!
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Joyce: Maybe the transmitter is off, maybe it's a communal aerial system which has developed a fault... Without knowledge of your location, preferably in the form of postcode or that of a nearby property such as a shop, it isn't possible to be more specific.
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Elissa: This might be the case.
It is so that not everyone gets all channels, or to put it another way, the Commercial (COM) channels don't have as good a coverage. Even for transmitters which do carry all channels, like Rowridge, not everyone can pick up the COM channels.
With reception it is impossible to say with absolute certainty without checking what is actually received. I assume that the terrain in Shanklin slopes downwards to the sea which means that those lower down may not have line-of-sight to the transmitter, which reduces chances of reliable reception.
We have also had someone posting on here who lives a mile or two south of the Rowridge transmitter and who has tried various things and been unable to receive some or all (I can't recall) COM channels. This could be indicative of the COM channels not being as powerful in the southerly direction, but unfortunately we don't know for certain because the powers that be won't release what are known as the radiation patterns, these which show how much signal the transmitter throws out in each direction on each channel it broadcasts. It is also the case that the frequencies used have to be agreed with France and possibly other countries so as to avoid interference. This could perhaps be another reason why the COM channels may be restricted.
If the aerial at the property you are moving to is horizontal (elements flat) and the COM channels aren't reliable then you might find that switching to vertical polarisation might help. This is because, usually, Rowridge transmits horizontally and vertically. But, the COM channels are lower power horizontally. In some cases an amplifier might help, or perhaps a change of aerial or mounting it higher up.
A postcode might allow us to give some better indication as to how likely you might be to receive all channels.
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Thursday 8 January 2015 7:09PM
Malcolm: No!
It will broadcast from the Oxford transmitting station directionally to the City of Oxford, and therefore will not serve Buckinghamshire at all.