Re post #9: "While on the lawn in front of the Gateway a couple of weeks ago waiting for the Merchant Navy service to start I glanced up at the roof and realised why PaulB's tv reception goes odd from time to time. The aerials point towards Dover Town Relay which isn't digital yet! Terry"
The last time this came up, a couple of years ago, I took some photos of the aerials on the Gateway. Each section of the flats has an independent aerial system. This comprises a high gain UHF aerial at the top, two VHF FM radio aerials below that, and a satellite dish at the bottom. The TV and Radio aerials will feed into a headend probably installed in the services hut that they are attached to, and the signals will be distributed from there to the individual flats in that section. The satellite dish probably feeds a multiswitch in the same location with independent feeds to each flat.
All the UHF TV aerials on the lower block of flats point towards the Dover Town relay mast as the signal from the main area transmitter mast at Hougham is blocked by the Western Heights.
Paul is lucky because his flat is in the higher block of flats at the docks end of the Gateway, which has an unobscured path from the Hougham mast. The UHF TV aerial on his section therefore points towards Hougham, as does the next section along. I think the end section of the higher block is obstructed by Burlington House and therefore necessarily points towards the Dover Town relay mast.
The photo below shows Paul's aerial system. As can be seen, the elements on the UHF TV aerial are horizontal as the signals from Hougham are horizontally polarized.
The photos below show the aerial systems on the lower flats. As can be seen, the UHF TV aerial is mounted at 90 degrees with respect to those on the higher block such that the elements are vertical as the signals from the Dover Town relay are vertically polarized.
The four analogue terrestrial channels are broadcast from Hougham on UHF channels at the top end of the UHF spectrum and the four from Dover Town at the lower end of the UHF spectrum, plus the former are horizontally polarized and the latter vertically polarized, in order to prevent mutual interference.
The digital terrestrial TV channels are only broadcast from Hougham so it is only Paul's end of the Gateway which can receive them, the lower block will not be able to receive them at all. They are presently broadcast at very low power to avoid causing interference with the analogue channels and our French neighbours but will be boosted to full power next year when it is the turn of the Southeast to experience the digital switchover.
There should be absolutely no problem with Paul receiving a perfect digital terrestrial signal in his block of the flats. He needs to check with the neighbours in his section to see what sort of reception they are getting. If they all getting bad reception, then the problem is with the aerial, the downlead, or the headend. If that is the case, then the company responsible for maintaining the system needs to have a look at it. If it is only Paul, then it is probably the socket in his flat or the flylead connecting from the socket to his TV setup.
The socket will have one outlet for TV and one for Radio. Paul needs to be plugged into the TV outlet and it is very important to have a high grade flylead. The ones sold at B&Q and elsewhere for a pound or two are very low quality and have very little screening so outside interference from cars going past or local interference from lights, fridges, etc, switching on/off will interfere with the low strength signals received on the digital terrestrial channels.
The fact that there is a satellite dish included for each section of the flats is interesting. Paul presumably therefore has a satellite outlet in his flat. This may be a separate socket or may be combined with the socket for the TV and Radio, as below. All he then needs is a cheap satellite receiver and all his problems with digital terrestrial reception are irrelevant. He will be able to receive every channel going with a Free to Air (FTA) box or all those plus all the Sky channels if he gets a Sky box and pays the subscription.
