All posts by Dave Lindsay
Below are all of Dave Lindsay's postings, with the most recent are at the bottom of the page.
Tony Hill: Which channels are you having difficulty with?
Rowridge's COMs are co-channel with those of Stockland Hill, so you could be affected by interference this way.
Rowridge's COMs are 50kW horizontally and 200kW vertically but the PSBs are 200kW for each polarity. The reason for the horizontal restriction on the COMs is because they are co-channel with Stockland Hill to the west and Crystal Palace to the north east.
As Stockland is only broadcasting horizontally, switching the aerial to vertical should help take advantage of the stronger signal from Rowridge and help reduce the level of interference from Stockland.
Unlike with some transmitters, a replacement aerial should not be expected to be needed for Rowridge as all channels are group A, as they were for former analogue.
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Philip Osborne: Wrexham Rhos is vertically polarised and Winter Hill is horizontally polarised so unfortunately a single aerial won't work for both.
Try a set-top aerial on each transmitter, manually tuning if possible, and definately confirming that you are watching the output of the transmitter you are testing. I have one of these Labgear aerials for use when a fixed aerial isn't available (other suppliers and models are available):
Set Top Aerial Labgear | eBay
I presume that you already know that Wrexham Rhos is Freeview Lite/PSB-only and that Winter Hill is a full-service transmitter and that this is the reason you wish to be able to receive from both so as to allow you to watch Welsh regional (PSB) programming and the Commercial (COM) channels only available from full-service transmitters.
For all things aerials, see ATV's site A.T.V (Aerials And Television) TV Aerial, DAB Aerial, FM Aerial.
As a non-professional, I would stick with a directional polarised aerial. An aerial's directivity (i.e. gain or sensitivity in one direction) is as the expense of that in others. This is the reason I would stick with a directional aerial.
Also, the gain of yagi aerials slopes down on lower UHF channels/frequencies. These traces illustrate the point:
A.T.V (Aerials And Television) TV Aerial, DAB Aerial, FM Aerial. gaincurves.html
In particular (and this is why I make the point), wideband aerials which are a greater compromise than group ones, are low on group A channels (see the wideband traces). Thus, a high-gain wideband aerial will have a "high" gain on higher channels, but group A ones will not be so. So don't be taken in by buying a wideband yagi aerial for Wrexham Rhos in particular as it uses group A channels.
Log periodic aerials are natively wideband but have a much flatter response and are therefore OK for Group A channels but they don't have as much gain as higher gain yagis.
See:
A.T.V (Aerials And Television) TV Aerial, DAB Aerial, FM Aerial. winterhilltx.html
A diplexer can combine the feeds from two aerials, providing the channels used allow, which for Winter Hill and Wrexham Rhos they are:
A.T.V (Aerials And Television) TV Aerial, DAB Aerial, FM Aerial. onlinesplittersandamps.html#TVTVdiplexers
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Keith Oxer: The channel has been lost because prior to carrying out the scan it wipes the memory.
If you wish to look to getting it back then the first suggestion is always to carry out a manual tune, if the set allows.
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teessider: First off I'd try a manual tune on UHF channel 46.
Do you have COM4 (ITV3) and COM6 (Film4)?
Do you know anything about your aerials? Do they have red tips?
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Gerry: A mast-head amplifier which you have may provide benefit with digital reception. It depends on your situation.
There is a wealth of information on ATV Sheffield's site. Basically the purpose of the amp is to make a small good quality signal into a big good quality signal. See:
Television Aerial Boosters / Amplifiers, Splitters, Diplexers & Triplexers
It is possible that there is too much amplification and with digital signals this appears the same as low signal. If the signal is high and overwhelming the tuner then the signal strength can jump up and down (there is also likely to be poor quality). If it gets even higher the signal strength could register no or little signal.
Exactly what happens varies by device, but be aware that poor "low" signal could be caused by over amplification.
What I suggest that you do is wait until 24th.
The full list of Freeview services is here:
DTG :: DTT Services by Multiplex
The COM channels (see that page) are at half power to the PSB ones from Limavady, so if there is difficulty with any, it will be likely to affect these. This doesn't mean that the signal will only propagate half as far or that half as many people will be able to receive it. It is likely to affect a few on the fringes of coverage. Unfortunately this is the compromise we have as the COM channels do not have as great a coverage as the PSBs.
As I say, I wouldn't worry about it; just see what you get come 24th.
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mckeownsean: RT channels will not be available via Freesat.
The transmitter that is used in your area would appear to be Divis. It won't broadcast RT but instead it will be broadcast from the adjacent Black Mountain transmitter. There will be many places where a single aerial will be able to receive from both where they are roughly in line.
From your location Divis is at 288 degrees and Black Mountain is at 265 degrees.
In order to receive RT/TG4 channels from Black Mountain you will need a Freeview HD receiver. The broadcasts will be in standard definition but they use DVB-T2 transmission mode which is that used for Freeview HD services, whereas standard definition ones use DVB-T.
The main thing I can see, and it will depend on your exact location, is that the white building to the left of the Radisson could perhaps be in the way for Black Mountain, but as I say, this depends on whereabouts you live and whether it is in that direction.
Try it and see on 24th, if you have a HD receiver.
If it turns out that you can't get RT from Black Mountain using your existing aerial, then it may be possible to replace the aerial (to get reception from Black Mountain and Divis), or failing that, Carnmoney Hill is also broadcasting RT and Digital UK suggests that you might be able to receive that.
As ever, take what the predictor says with a pinch of salt. Local obstructions are not taken into account.
Reception of RT from Carnmoney Hill (if possible) would require a separate aerial and this (along with the Divis one) could be combined into one feed. Again, you will need a Freeview HD receiver to watch it.
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mckeownsean: Or it "may" be possible to receive from Clermont Carn in Co. Louth. I have spotted an aerial which appears to be pointing at it near to you on 36 Upper Stanfield Street, so this may add weight to that as a possibility.
That said, it is important to emphasise that local buildings could scupper your chances and therefore what can and cannot be received from varies from property to property.
The only warning to give is that reception of Saorview signals from Clermont Carn will probably require a Freeview HD receiver. This is because of the different digital systems used in the UK and in the Republic of Ireland.
If you go down the route of receiving from Clermont Carn, then these questions might be of help:
Advice for people who receive UK overspill signal | SAORVIEW
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mckeownsean: And finally, Clermont Carn will not go onto full transmission power until 24th, so don't do anything before then.
The NI Mux from Black Mountain and Carnmoney Hill will carry RT One, RT Two and TG4 only. See:
What is Saorview? | SAORVIEW
Clermont Carn will carry more channels:
What is Saorview? | SAORVIEW
As I say, your possibilities depend on what can be received at your location.
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Tuesday 9 October 2012 12:11PM
Andrew Haddow: It might be worth seeing if the reception on the TV is any better by feeding the aerial directly into it.
The idea is that the signal coming out of the Humax is the same as that going in, but in practice it is not exact and in situations where the signal is touch and go the slight variation could play its part.
As ever, it's a "try it and see" sort of thing.