I have a loft aerial (Yagi type (9 verical elements; 2 reflectors, wideband, directional, and connected to a distribution amplifier) pointing towards a transmitter (relay) and get good reception (high S and High Q).
On occasions, usually in the early morning (say 2am), I can receive some signals from another transmitter that I believe is about 90 degrees to the boom (parent). These signals are not transmitted from the relay. At other times during the day this signal (parent) is very weak and unwatchable.
My question is: Is it possible to enahance these weak signals at 90 degrees with little effect to the forward direction?
I would be reluctant to alter the position of the aerial due to my current exellent reception, and the difficulties of working in the loft.
It would not be possible to point the aerial at the main transmitter from the current installation. The best I could do would be to point the aerial between the transmitters (almost certainy lose all reception). Although I can receive some signals from the main transmitter, I am not confident that I would be able to receive all the multiplexes. People around me all use the local relay transmitter because of geographical considerations.
Another aerial. This other transmitter is probably not vertically polarised and maybe on a different part of the band. So shove up another aerial and have a switch, One issue of course is that Freeview seems unable to cope sensibly with duplicates, throwing them up on channels above 800, or more worryingly getting them all muddled up so some are from one site and some from the other one. Brian
As others have said, get a second aerial and direct it at the other transmitter, and combine the outputs from the two aerials. But it's not that simple in practice. I was / still am thinking of doing this for myself. There's a recent thread on uk.tech.digital-tv entitled 'Coax Y adapter query' where the pitfalls and correct way of doing it are discussed at length.
You have posted this on cam.misc and got some sensible answers there.
I did ask you if you could tell us which transmitters are in use then you could get some sensible practical answers.
Sometimes but very rarely this can be done, but posting in the ng you originally did if you are in that area a simple Y combiner will be asking for trouble most all of the time.
If however if you are somewhere else then it "could" be done but you'd need to go the right way about it.
Your best bet is to tell us where you are located and what transmitters you are attempting to receive until you have done that there isn't any really useful help to be had!...
I have a reasonable knowledge regarding the transmitters, locations, polarisations, powers, etc, etc. I tend to post to a number of groups since some people read some, but not other groups. Hence, I hope to gain as much information as possible, as this helps me learn, and make better judgements.
I think he must be an example of the classic Labour/Green voter. If you go one asking the same question long enough, eventually someone will give you the answer that you want to hear, at a very expensive price.
It won't naturally *work*, but it will make you feel better.
If you are going to all this trouble to get extra region channels, why not just put up a freesat dish and get 'em that way? Reception quality will be better.
£100 all in, for an installer to visit, fit a dish and leave you with a HD freesat receiver. Or DIY....
but, how you should go about your project depends on the channels in use. If you want proper help, then you need to say which transmitters are involved.
Well if we knew what you know then we might be able to help you better;!..
However for the benefit of other curious UK DIY'ites
Someone in another reply suggested these might be Whitehawk Hill and Saltdean. Now if that is the case it seems to me to be rather pointless as they both will carry the same programmes as I believe that Saltdean is a relay of Whitehawk Hill. Thats to say it receives that station and frequency converts it to other channels and re transmits what its receiving..
Here and there..
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?txid=573And those channels are rather close together in frequency terms.
Now say you were in a location where you received a rather strong signal from a Main station. And that station was say in what's called Group A thats from channels 21 to 34. Lets call that the "Local" aerial.
Now if your more "distant" (lets refer to that as the distant from now on) station was in the SAME aerial group and you did a simple "resistive splitter" arrangement and connected another aerial in group A again to that you'd very likely have the following problem. The local transmitter will now be picked up by the "distant" aerial, and the signals from that will be added to the one being picked up by the "local" aerial.
Now the phase of the two signals will be different and they will take differing paths from the transmitter to reach your TV. This can result in constructive and destructive interference thats where the signals will add and subtract due to the phase differences let alone the time delays. The Digital TV system will cope with some of that but not what your now likely to be presenting your TV with!. In analogue times this would have caused very bad "ghosting".
Consider the distant station. Now apart from the weaker signals from that your adding in the local much stronger signal and most likely that will "swamp" the input of your TV and it may have a hard time actually receiving the signals receiving the weaker signals on almost the same channels.
We had this problem in Cambridge many years ago. Some people wanted the extra, in those days!, films that ITV London transmitted. Now thats carried by the main station at Crystal place in London. The local ITV came from Sandy Heath they both used channels in aerial group A and as the London signals were very weak you had to use an amplifier. Now combine that lot together and the results wouldn't work!.
Now take a different scenario.
If your distant was up in group C say channels 50 to 60 odd for example then you are in a better position because you can filter the input from each aerial thats to say only allow group A signals thru from that aerial aimed at the A group transmitter and you can filter the distant aerial and signals therefrom so they can be separated as it where. Also your distant will pick up some reflected signals from the local transmitter but as its filtered these do not add and upset reception of that station.
Also when your TV is trying to receive the group C signals its now presented with very strong channel at the that frequency and can thus differentiate those better so this may now become possible.
Now if you start adding amplifiers without carefully considering their effects you can easily overload them and cause what's called intermodulation which will produce spurious signals up and down the band and present your TV with phantom signals which lets say, will upset it!.
Thats more or less what you need to know, of course there will be some odd instances where thats not strictly correct, but for the main part....
Except Saltdean (from which the O/P receives good signal with direct line of sight) is 3 mux Freeview-Lite, but Whitehawk Hill (90 degrees off beam and believed to be skimming the hilltops) is the full 6 mux Freeview.
Yes one of the well thought out aspects of UK Digital TV;!..
Well if I were him I'd do my best to get the best aerial I could onto Whitehawk Hill which will almost certainly mean putting it outside and a high gain one to boot. Theres really nothing you can add onto an existing IIRC loft aerial thats say 90 deg off beam to improve matters. Amplify it and you'll more then likely run into intermod problems..
Or do as another poster suggested go Freesat an ex Sky box with a freesat card is a DIY project, the sat dish as long as it can "see" the sats and you could do that in a back garden if it was clear line of sight to the right bit of the sky, would be a very good alternative!...
As some people are starting to do faced with the lack of full DTV coverage..
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