All posts by Steve Donaldson
Below are all of Steve Donaldson's postings, with the most recent are at the bottom of the page.
Adam Jackson: I remember you now! I know we talked on here a few months back to someone in St Nicholas.
In which case, as all three channels went then Blaenplwyf's COM channels must be the prime suspect as they are relatively local. The terrain map and plot, and the coverage map on this site suggests that their normal availability is up to the high ground to the north east of St Nicholas, between St Nicholas and Fishguard.
The Trefin transmitter had quite a power increase at digital switchover. The former analogue was 56W and 7dB down on that is 25W. -7dB with respect to analogue provides the same coverage for digital. The powers are now 100W (PSB1/2) and 72W (PSB2), so roughly a tripling and quadrupling of power. Prior to switchover, Blaenplwyf and Trefin were not co-channel.
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E McC: Holywell Hill is on channels 22 and 25. If you are using a Freeview box or TV then the channels from Holywell Hill will be put in the 800s (meaning on logical channel number 800 upwards).
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nick : This page on A.T.V. is on combating co-channel interference. A high gain antenna and attenuator is one approach, where the objective is to increase the ratio of the wanted signal to the unwanted one:
How to combat co-channel interference A.T.V. Poles, Brackets, Clamps & Aerials
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Margaret Bacon: Since about Saturday there has been high pressure causing reception issues across much of the country. The effect is to cause signals from distant transmitters to travel much further. These can be from elsewhere in the UK or abroad, and when the signal is on the same frequency as the transmitter one is tuned to then this can result in picture break-up or no reception at all, depending on how strong the interfering signal is.
If you are using the Whitehawk Hill transmitter then in order to restore ITV, C4, C5 etc. then you should carry out a manual scan of UHF channel 35. If the interference is still there then you may find you can't tune it in, in which case you will have to try again at some later time.
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E McC: There are a number of variables so can you answer these questions and we can provide more information.
Which direction is the aerial pointing? Is it west or thereabouts? Or is it roughly north east?
Are the elements of the aerial horizontal (elements flat) or vertical (elements up/down)?
Have you had this aerial installed with the hope and expectation of receiving both Freeview (BBC, UTV, C4 etc.) and Saorview (RTE, TG4 etc.), or is it just for Saorview?
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Nick : Should you not be aware, I have made the observation that the Chalford relay broadcasts on channels 21, 24 and 27 with vertical polarity. It has been co-channel with Ridge Hill's COMs since digital switchover. This is not to suggest that it might be the cause of your reception issue.
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Philip Nicholas: Use manual tuning to add the missing multiplex. The BBC standard definition TV channels and BBC radio stations are all carried on PSB1 multiplex, aka 'BBC A'.
The UHF channel you need to tune to depends on which transmitter you are using, the one your aerial points to. From Carmarthen, Carmel is roughly eastwards and PSB1 is on UHF channel 23.
Preseli is roughly west from Carmarthen and its PSB1 is on C43.
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Geoff. Doxon: If your question relates to when the Kendal transmitter at Oxenholme may transmit all Freeview channels, then I imagine that it's extremely unlikely. A few transmitters became full service when TV transmitter frequencies were reorganised to clear the top ones for use by mobile phone services.
My cursory familiarity with the Kendal area is that the Lancaster transmitter is receivable in some places, this judging by the Freeview predictor and the fact that some houses have Lancaster aerials.
Lancaster carries BBC One North West and ITV Granada, whereas Kendal (Oxenholme) carries BBC One North West and ITV Border, so if ITV Border is important to you then a two-aerial approach may be the way to go.
That said, as Lancaster is possibly out of sight or not far off, reception may be expected to not be as reliable as Kendal or Kendal Fell. Thus, with an aerial on Lancaster and one on Kendal (or Kendal Fell, depending on which is best), it may be preferred to rely on Lancaster only for the channels that one of the Kendal transmitters doesn't carry.
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Monday 9 October 2023 7:20PM
Adam Jackson: While there may be other possible reasons, it may be worth noting that PSB1 on C25 and PSB2 on C22 are 100W and PSB3 on C28 is 72W. This appears as such in a spreadsheet titled "Complete DTT Frequency Plan" which I have saved from 2013, which tells us it's been like it since then.
The only reason I can think that they are on higher power is because there is another transmitter which uses C22 and C25 but not C28 which has been calculated as a potential interferer and they have upped the power in effort to compensate.
This doesn't prove that this is the reason you and your neighbour have had difficulty over the last few days, but it is a hypothesis that you may wish to consider.
The question then, is which transmitter or transmitter might it be? Blaenplwyf uses 22, 25 and 28 for its COMs, so it doesn't make sense to suspect it.
I wonder if the GE06 agreements between Ireland and the UK may give the answer. For the 800MHz Clearance agreement dated 1 June 2012, Trefin had added for channels 22, 25 and 28: "Slope across; 2dB | 275 degrees | Waterford; 1dB | 285 degrees | Waterford". In the table this is written on three separate lines -- I've denoted a line break through use of the semicolons. This is an addition, not a modification to an entry at on a previous agreement.
For the 700MHz Clearance, dated 24 March 2017, for the three channels of Trefin, in the "Action" column (where is says either "no change", "addition" or "modification") it does say "no change". However, the clearance agreement has had added (since the 700MHz Clearance agreement) entries for Arklow/Wicklow for C22 and C25 but not C28 (C28 remained as per the 800MHz Clearance agreement).
The agreement for C22 and C25 at Trefin (but no C28) now reads "Interpolate 2dB | 275deg to 1dB | 285deg | Waterford; Interpolate 0dB | 320deg to 1dB | 330deg and 1dB | 331 - 334 | Arklow/Wicklow".
Now let's cross-reference this with what's actually being transmitted from these Irish sites. In Ireland there are only two multiplexes but the international negotiations are for six multiplexes. This begs the question: does Waterford use 22 and 25? It has international clearance to use 28, but does it not do so at present?
The "Digital Television Transmission Network" document from 2rn dated September 2019 Gallows Hill, Waterford using 22 and 25 with vertical polarity and ERP of 250W.
The "Saorview bulletin" dated July 2019 sets out the transmitter network post 700MHz Clearance, including listing the transmitters which were to change channel and their old channel. Wicklow was a new transmitter on 22 and 25 with vertical polarity at ERP of 250W.