All posts by Dave Lindsay
Below are all of Dave Lindsay's postings, with the most recent are at the bottom of the page.
Gordon Ormston: The fact that analogue is very poor and snowy suggest that the problem isn't too high a signal level.
The bit about connecting loosing some signal was intended to be a crude attentuator to reduce the signal level.
Based on poor analogue reception, this would tend to suggest that you are in a poor reception area and not one where your receiver could be suffering from the effects of too much signal.
I used Megalithia to plot the terrain from the transmitter to your location:
Terrain between ( m a.g.l.) and (antenna m a.g.l.) - Optimising UK DTT Freeview and Radio aerial location
This suggests that you may (just) have line of sight, although bear in mind that ground levels for the plot are sampled at intervals and it may go higher within these samples. This also does not take into account any obstructions such as trees and buildings.
It could be that you have poor reception because of the umbrella effect. You will note that you are 100m below the ground that the transmitter is sat on.
Transmitters put their main beam out towards the horizon. Its strength helps carry it. Thus, the closer to the transmitter you are, the more likely it is that you will be under the main beam, as it were. But there should still be sufficient signal. But the issue you "may" have is due to being so low down.
Could you (can you) receive (the lower power) Freeview signals before switchover?
I'm not an aerial installer, so I'm not sure what else you could try.
Having read your comments, perhaps the only thing that you can do in an effort to receive terrestrial television is to get an aerial installer in. Or go with Freesat.
There are some channels that are on Freeview, but not on Freesat, e.g. Yesterday and Dave. However, these are carried on the (Freeview) Commercial multiplexes and these are on lower power than the Public Service ones from Dover. So you "may" find that you can only receive the Public Service channels from Dover, all of which are available on Freesat.
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Peter: Unplug the aerial for the first 30% of the scan to miss out Eastbourne's Group A channels.
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Peter: Try connecting a receiver directly to the aerial and work from there. That way you are discounting the possibility with the distribution amp and cabling causing an issue.
Once you have Heathfield channels tuned in your receiver's memory, then refer to the signal strength screen for one service on each mux.
This page shows the services by mux: DMOL Post-DSO Multiplex Channel Allocations
So focus your attention on:
- BBC One (PSB1)
- ITV1 (PSB2)
- BBC One HD (PSB3)
- ITV3 (COM4)
- Pick TV (COM5)
- Yesterday (COM6)
Of course, your aerial "may" always pick up Eastbourne even though it points horizontally to Heathfield simply because Eastbourne is so strong.
Some receivers store the first channels found during the scan, and more sophisticated ones choose which to go with by assessing strengths having completed the scan. Whilst you will hopefully achieve a result where Heathfield is the stronger, the latter "may" always be an issue.
Different receivers are designed in a different ways. Some have limited functionality when it comes to manual tuning, signal strengths and other technical information. It might be worth looking at what devices you have to see which might be most useful to help you site your aerial.
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Peter: Could it be the roof-tiles blocking the signal too much? Have you tried pointing the aerial out of the window (even if it's lower than the loft you are fitting it in)?
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Rob: Different receivers have differing sensitivies, and the signal may be marginal (i.e. a bit touch and go).
This is particularly the case as the Commercial multiplexes from Caldbeck (which carry Film 4 among others) are on low power until 24th October when Northern Ireland switches to digital. This is so as to protect against interference with its pre-switchover signals.
If your problem TV has manual tuning, then you need to manually tune to UHF channel 29.
Other possibilities include taking the problem TV to the aerial socket used by the other TV. Or if the TV aerial is fed via another box (e.g. a recorder), then try removing the box from the wiring so that the aerial socket is connected directly to the TV.
If the TVs are running off the same aerial and you are using a powered booster to split the signal, then try reducing the level of amplification (if it allows). If you can bypass the booster/splitter and connect the aerial to the feed directly to the problem TV to see if it makes a difference.
Once you have Film 4, Yesterday and other services on C29 (the "ArqB" multiplex), then don't retune. If you loose them then it is a problem with lack or too little signal and not tuning. Retuning is likely to result in wiping the services from the memory.
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Gordon Ormston: The analogue signals will be radiated from the antenna system at the top of the mast. Because of their high power, I assume that the main beam is higher (to the horizon) whereas the lower power signals are radiated from antennas lower down and because they are lower power, I "wonder" if the beam is aimed a little lower, which makes it better for you.
Obviously the post switchover signals are on a par with the old analogue ones, which is why I wonder if you're always going to have difficulty.
As I say, I'm not an installer and I'm not an expert on TV transmitters, but as a technically-minded person, I wonder if the above is your problem.
Maybe have a look around and see what your neighbours have with regards aerials, although obviously some may have been put up to receive pre-switchover signals (not that they won't work after, of course).
The only other thing is are there trees in the way of your aerial, because they could be shadowing the signal, a signal which may not be great in the first place (as suggested above). If so, could the aerial be moved to get a better view?
Or will a taller mast allow sight above the trees? I appreciate that the answer to this question may well be no, or may be "yes, until they grow a bit more".
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Gordon Ormston: I have looked at Riverside on Streetview and I can see the trees in the direction of the Dover transmitter. I can also see that the aerials on the two houses at the end of the road are pointing in roughly the opposite direction at Crystal Palace or Bluebell Hill (these being only a couple of degrees apart). Presumably they have given up on reception from Dover, although the tall large aerials show that their reception is very difficult.
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Craig: Look at www.aerialsandtv.com for information.
As Mark says, if you have a C/D aerial, then it will be unsuitable for Pendle Forest.
What aerial you need probably depends on what sort of signal you have. In the best areas, use a log which are naturally wideband, but have a flatter response than yagis.
If it's not so good, then a Group A yagi aerial as suggested by Mark might be what you're looking for.
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Rob: No problem. If you're looking for information and professional guidance on this, see www.aerialsandtv.com
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Monday 18 June 2012 1:12PM
R FLETCHER: You've posted this on the page for Darwen transmitter.
The problem you are experiencing is common in Eastbourne for people who are receiving from Hastings transmitter. See the Hastings transmitter page:
Hastings transmitter | ukfree.tv - independent free digital TV advice
The Hastings transmitter's Commercial (COM) channels, which carry the services you've mentioned, use the same channels (frequencies) as the relay on the top of South Tower in Eastbourne. Unfortunately South Tower only broadcasts Public Service (PSB) channels and these are those which you will still be able to receive from Hastings.
The only possible way to pick up the COMs at your location would appear to be Heathfield. Whether this is actually possible would have to be determined by an installer whilst on-site. However, the predictor suggests that it "may" be possible (this doesn't take into account local obstructions such as buildings or trees that may prevent reception).