All posts by Dave Lindsay
Below are all of Dave Lindsay's postings, with the most recent are at the bottom of the page.
Johnny: (See above to my posting of yesterday @ 10:46PM for an explanation as to why you only have some channels.)
The only thing you can do is investigate the possibility of receiving directly from Limavady, although even then, the COM channels are on lower power and may be difficult. I looked on Streetview and can see a few aerials on Limavady, although as I say, the Commercial channels "may" be unavailable - that is, the fact that aerials point to Limavady doesn't mean that they are sufficient to receive the COMs.
Saorview signals are broadcast using DVB-T standard. These signals carry a HD picture which is encoded using MPEG4 format.
Freeview standard definition signals use DVB-T standard whereas Freeview HD signals use the newer DVB-T2 standard. Hence a receiver that doesn't have a DVB-T2 tuner cannot receive Freeview HD.
What is interesting is that Freeview standard definition pictures are encoded using MPEG2 and as such a lot of Freeview standard definition receivers don't have the capability to decode MPEG4 (used by Saorview). Evidently yours does. May I ask what is the make and model of the receiver you are using to receive Saorview? Also, is it a "Saorview" labelled product or a "Freeview" one?
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Johnny: It comes back to politicians not mandating licence-holders to broadcast from the relays. They have been allowed to pick and choose what suits them rather than working to provide a (more) universal public service.
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seamus o'doherty: I did refer to them as "smaller" rather than "small".
Maybe it is your sense of humour...
Anyway, this document lists the number of households expected to use each transmitter:
http://consumers.ofcom.or….pdf
I haven't found a way of putting it into a spreadsheet, but having just looked down the list, I think that Derry is the largest relay to be PSB-only. Strabane with 14,000 households is nowhere near coming second.
The sizes (smaller/larger) are a measure of the number of households they serve rather than the length of the mast!
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Johnny: Undoubtedly the whole Freeview Lite thing must be the biggest let-down.
The page on the LG site about your TV is:
LG 42LH3000 Television - 42" HD Ready 1080p LCD TV - LG Electronics UK
You will, of course, have to switch your aerial to horizontally polarised. For lots of information about aerials, including an online shop, see ATV Sheffield's site A.T.V (Aerials And Television) TV Aerial, DAB Aerial, FM Aerial. (It says that there is an additional charge for orders to Northern Ireland.)
See this page for suggestions for Limavady:
A.T.V (Aerials And Television) TV Aerial, DAB Aerial, FM Aerial. digitalnationwide2.html#L
Derry uses Group B channels whereas Limavady uses Group C/D ones so you may need to replace the aerial. In any case, you may be looking for something with a higher gain. However, you might be able to use the current one for test purposes with Limavady.
Use manual tuning to select the Limavady channels. Select a UHF channel and wait a moment for the strength and quality to show (but don't press "Add" just yet). Doing this will allow you to use your TV as a meter.
The objective isn't to see the signal strength at 100%; it is quality that matters.
The six UHF channels from Limavady are:
PSB1 | BBC One | C50
PSB2 | UTV | C59
PSB3 | BBC One HD | C55
COM4 | ITV3 | C54
COM5 | Pick TV | C58
COM6 | Film4 | C49
In order to receive RT you will need a separate aerial. I guess that you may have one now and that it is pointing to Holywell Hill which is just over the border and not far from Sheriff Mountain. Unfortunately Holywell Hill is horizontally polarised and Sheriff Mountain is vertically polarised else you may have got away with a single aerial for both (as they are on bearings only 14 degrees apart from your location).
If you have combined the two aerials into one downlead (so as to feed it into the same receiver without having to swap aerial leads) then this should still work for Holywell Hill and Limavady.
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john boyd: The purpose of an attenuator is to reduce the signal level coming down the aerial lead. They may be needed in cases where the aerial is "pulling in" too much signal now the signals are stronger.
The purpose of increasing the power of the signal (at switchover) is to increase the coverage area. This is not the broadcasters "getting it wrong" unless you only measure their success by whether you can receive the signals adequately or not.
Of course, it is not the responsibility of the broadcasters to adjust viewers' aerial systems (including installing attenuators where necessary).
A crude attenuator is to remove the outer part of the aerial plug (if it screws together) or hold the plug in close proximity to the socket. If the quality improves this may give an indication as to whether it could be too high a signal level that is the problem. Wait several seconds before the signal meter on the screen catches up.
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john boyd: Some devices have an in-built "booster" and this should probably be set to off.
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neil: See this posting which explains why:
Londonderry transmitter | ukfree.tv - 10 years of independent, free digital TV advice
The Licence permits the holder to watch television and does not mean that reception is possible. In any case, it goes to the BBC and as a Public Service Broadcaster, the BBC broadcasts from the Ravenscar relay.
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Johnny: The only other thing I will say is that the Digital UK Postcode Checker "thinks" that COM4 and COM5 are "poor" at your postcode whereas COM6 is "good". The figures that it calculates are the percentage of the area of the postcode that are "served" and "marginal". It should be taken with a pinch of salt as such predictors can never be entirely accurate.
The reason I raise this is because I have been wondering why the marked difference between COM6 and COMs 4 and 5. Unfortunately it doesn't let on why it has calculatated it like this!
In some cases one can make a guess that the likely reason is due to a particular transmitter that uses the same channel. This transmitter, the predictor "thinks", may act to degrade reception. But as reception prediction is not an exact science, so too is interference from unwanted signals.
The only thing I can think is that the calculation has taken into account a former analogue transmitter in the Republic. Interestingly those which used 54 and 58 used 64 as well (but not 49). So I think that this is probably nothing to be concerned about.
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Sinead: To tune in the RT/TG4 channels, go to the manual tuning function. If there is an option to select the mode, ensure that it is set to DVB-T2 rather than DVB-T. Then select UHF channel 39. Don't press the button to scan/add channels just yet; if it gives an indication as to strength/quality on that channel note what it is.
The signal that carries RT/TG4 is broadcast from Black Mountain whereas the other Freeview channels come from Divis. Because the two are close together, for many people this is OK because they are in roughly the same direction and hence one aerial will work for both.
Because you are so close the two transmitters are 41 degrees apart. This could perhaps pose an issue. If so, then maybe turning the aerial slightly anti-clockwise (towards Black Mountain) might help.
Failing that, you may be able to receive NI Mux with a second aerial on Black Mountain or Carnmoney Hill. Or, having looked at Streetview, some of your neighbours have aerials on Clermont Carn in the Republic. These will provide all Saorview channels which your Freeview HD box will work with:
What is Saorview? | SAORVIEW
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Thursday 25 October 2012 2:19PM
Kerry: I made a posting about this on the Brougher Mountain page:
Brougher Mountain full-Freeview transmitter | ukfree.tv - 10 years of independent, free digital TV advice
Up until now I have never seen such a marked difference in strength of PSBs vs COMs. It would appear that this is the way it is going to be.
Unfortunately it could be that the high-power PSBs, which are on adjacent channels to the COMs, could be causing your receiver to be desensitised. See the Brougher page for more of an explanation.
I imagine that you aren't alone. Whether you can strike a balance by using an attenuator (or removing booster) is something that can't really be predicted - it's a try it and see sort of thing.
The COMs are on (a bit) higher power than they were before switchover.