We are more than willing to give advice to those actually purchasing from us. Could those only seeking information please just find the answer somewhere on this site, or ring an aerial installer local to them, or call the reception advice phone numbers.
If you`ve found this site informative and, hopefully, interesting as well,
The first trip we took after the (complete) switchover over reminded me very clearly how finding the best digital signal is so much harder then finding the best analogue signal was. The main problem is that the digital signal is either there or it isn`t, though there is a narrow band of signal quality when the picture`s there but it`s breaking up and freezing all the time.
The first night we were moored at Claverton (visit the pumping station, very interesting) on the Kennet & Avon canal. We were right in a valley and there wasn`t a house nearby so I could check which transmitter it was getting its signal from ! I pressed on, but despite me having the advantage of knowing the direction and polarity all the transmitters even when using the DM Log the TV`s tuner couldn`t find any signal off Mendip, Ridge Hill, Oxford, Hannington, Rowridge, or even the Bath relay. Salisbury did give a bit of a signal but it wasn`t usable. This complete absence of signal has never happened anywhere before (in fact I even suspected the TV was faulty) though I only mount my aerial only about 18" above the boat`s roofline because I don`t have the option to mount a higher pole on a hire boat.. Not that I`m saying a higher aerial pole would necessarily have made a significant difference. Obviously, at this site, the boat`s Omni type aerial didn`t find anything at all, even off Salisbury. As an aside were we were moored there were trees all round us so even a satellite would not have worked. Anyway, we stopped at Bathampton the following day which is right next to Bath transmitter and the TV operated satisfactorily there, in fact even the Omni aerial worked in that location !
Of more interest was when we moored at Hilperton. There, even though it was through trees, the DM Log managed to get a reliable signal from off the first transmitter I tried which was Mendip. However when I tried the Omni as an experiment the signal was breaking up all the time.
I`m unconvinced if the TV`s tuner was sufficiently sensitive (they do vary), but even so, TV reception wise, it was a sobering trip. I suspect that with analogue we`d have always got something, even if at Claverton it may well have been grainy and ghosting, but, unfortunately, analogue`s gone........
So, a reminder of the overwhelming importance of signal strength. In some spots you won`t get anything whatever aerial you use, whereas in some spots even an Omni will work. What`s most interesting to me are the areas, like Hilperton, where a decent aerial will get you something, but a crap aerial won`t.
As mentioned above, we spent a night at the foot of Bosley Locks, 4m NE of Congleton. All of the other boats seemed to be on Winter Hill with their aerials pointing NNW. Since there looked to be a reasonably clear “line of sight” in this direction I went with it and it worked reasonably on the Log Periodic. The following morning I thought I`d experiment with the Omni and got the TV to do a search with it connected. Much to my surprise it was picking up a reasonable BBC1 on CH 52 and BBC2 on CH 45. Now I`d done a bit of research on all the likely transmitters in this part of the world, but none had those programmes on those channels. I was intrigued. Referring to my trusty little BBC/ITC booklet “Television Transmitting Stations” (they don`t do it any more, you`ve got to print reams of A4 off the websites, such is “progress” ) I realised it must be Moel Y Parc !
I cranked the Log over to the West (Moel is the same polarity) and connected it up, result, almost perfect pictures.
Apart from proving the usefulness of an Omni as a transmitter finder, it also underlined yet again how important “line of sight” is. Remember that Winter Hill was 34 miles away and kicksed out 500kW (analogue), Moel Y Parc was 48 miles and only transmited at 100kW.
Gordon Bennet, an Omni TV aerial is smarter than I am, not good for the ego....
NOTE ! Most of the tests on this page are on analogue transmissions but analogue signals showed up small differences in signal strength/quality better than digital signals so the tests are actually more meaningful than those on digital transmissions.
Below is an extract from our transmitter map showing Bosley, Moel Y Parc & Winter Hill.
There are some other smaller repeater transmitters in the same area (Over Biddulph, Congleton, Langley and Macclesfield) which can be seen on the full size version of the aforementioned map, or see Ofcom`s PDFs or Digital UK (use the drop down menu to change the region).
The fact a large aerial is out of the question is probably a blessing in disguise, because it is highly doubtful that the mounting for it (on a boat or caravan) would be strong enough to withstand a strong wind anyway ! On the subject of bracketry and poles, that`s another problem, because aerials should be mounted as high as possible (particularly in poor reception locations) and it`s doubtful that the average boat owner / caravan owner wants a 20ft mast bolted to the side of their pride and joy. That said, a lot have satellite dishes, and they`re hardly aesthetically pleasing either, especially on a canal boat......
1 The direction of the transmitter is the most obvious variable, your aerial must be pointing at it (unless you`re right next to a main transmitter ! ) or your picture will be poor.
3 The third variable is often overlooked, and that is the polarity of the transmitter(s). If you get the wrong polarity you could be losing up to 90% (or more) of your signal, which isn`t to say it won`t still work if the signal strength is high enough, but if it isn`t, well, no Coronation St for you.
Also see maximising picture quality
If you get a good picture off an Omni TV aerial it`s because you`re in a good signal area, I reckon that a coat hanger* would work just as well, in fact it may well work better. The fact is that in a poor signal area an Omni aerial is about as much use as a 2nd World War Italian Kamikaze squadron**.
It is possible to eliminate two of the variables mentioned above, namely direction and polarity, by using an omnidirectional or "Omni aerial". The problem with this strategy is that, how can I put this, Omni`s are crap...... In fact the gain of an Omni is actually negative. Theoretically the gain of an Omni directional aerial is minus 3 dB, and that`s without taking into account the additional loss of signal that results from an incorrectly polarised antenna. Furthermore an Omni`s beam width (to eliminate unwanted signals), is, well, 360° !
The DM Log is pretty strongly made and because it`s nearly all metal in construction it`s eminently fixable if it gets damaged, as any touring aerial is bound to be...... Furthermore, Log aerials are flat, thus making storage much easier and lowering the risk of the antenna being damaged. At a conservative estimate the gain of the DM Log would be about 6 to 7 dB and since we use it as a control aerial for all our antenna testing its relative gain to all our other aerials can be seen on the relevant graphs. Now it must be admitted that 7 dBd is not "high gain", but since all high gain aerials are large, and as such are unsuitable for boats or caravans anyway, I wouldn`t worry about that too much, particularly, as we`ve just discussed, when an Omni has minus 3dB of gain. So, compared with an Omni, a DM is high gain !
On the subject of which, we sometimes get asked if a Log36 would be a better choice (for a boat/caravan aerial) than a DM Log because its gain is a bit higher. Well yes and no would be my answer. You do get a bit more signal out of a Log36, but on the other hand the DM Log is 10in shorter, it has a tilting clamp, and, most importantly, it`s more easily fixable if it gets damaged. Whilst testing an aerial I once bent some of the alloy rod type elements on it, but when I tried to straighten them some just broke off ! Furthermore, if any spares are needed for this aerial (or any other purchased from us) we`ll try and get spare parts for it if possible. Lastly, the DM Log also has a handy 6" trailing lead c/w rain proof cover, so, basically, I`d always recommend the DM Log, and only the DM Log.
Note : we recommend that all Log Periodic aerials are installed slightly tilted up at the front end.
DM Log aerial
It`s the only antenna we recommend for boats and caravans.
Before we go any further, don`t forget the obvious, which way are the other aerials facing/polarised ? And this is likely to be more accurate for any houses (as opposed to other boats or caravans) as they were probably put up by an installer with local knowledge.
Extract from our transmitter map.