All posts by Michael Rogers
Below are all of Michael Rogers's postings, with the most recent are at the bottom of the page.
Sunday 21 July, midday : On the North Devon coast, Carmel channel 48 received. Weak signal, but without pixelation. Reception here is affected by the high tidal range in the Bristol Channel affecting the signal to varying degrees. So the Carmel transmitter is operating as scheduled. Both Arqiva-A and Arqiva-B are weaker transmitters, so can be the first to "wobble" in adverse propagation conditions. If others are not receving Carmel ch 48 overland (ie in South Wales) it just might be that the radiation pattern has been modified by Arqiva to address possible interference with the Ilfracombe relay.
I look forward to further reception updates from South Wales!
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Postcript: to receive the new wider range of frequencies from Carmel on channels 23-48 (490-690 MHz) a wide-band aerial (eg a "log-periodic) will be necessary unless a strong signal is received.
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Regis and all:
If you received Kilvey Hill before, it should still work on the new channels. A clean retune, as recommended by Chris, will delete redundent channels and select the new Kilvey Hill channels (21,22,24,25,27,28). If your aerial is vertical and points at KH, you might receive a better signal from Carmel (channels 21,22,24,25,27,28) with the aerial horizontal, but pointed roughly in the same direction. I can receive both KH and Carmel, the latter being more reliable, although both can be affected by the 7meter tidal range in the Bristol Channel. Note that the new Ilfracombe relay channels are now the same as three of the new Carmel channels, so, despite opposite polarisation, interference might result - as we had some years back :-( If you can receive Ilfracombe (aerial vertical) it only offers the three main multiplexes, not the full complement of six as from KH and Carmel, but it is good for Southwest news. For all the new channels, a wideband aerial would be the most reliable. A Group-A aerial would struggle with the Carmel Arqiva-B multiplex. If you are able to tune channels in *manually*, you can select the channels you want, with six multiplexes from Wales, possibly plus BBC and ITV Southwest from Ilfracombe. If you use the automatic tuning option, in its inscrutable wisdom it will probably select weaker channels... Fallback position : forget the Ilfracombe relay and manually select either KH or Carmel and get SW news via the internet. Hope this helps!
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North Devon coast at 23h34 : YESTERDAY on Channel 48 from Carmel received with some pixellation on an inside short log-periodic aerial. When I find time, I will put up a better and higher outside aerial.
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Chris, you might wish to ask Arqiva whether the radiation pattern OR the position/height of the antenna on the Carmel mast has changed. Respondents can be very canny with generalisations; specific queries just might elicit some useful info! At this moment, 22 July 09:38, channel 48 from Carmel is stable on my mini-log (Antiference Silver Sensor) pointed out a groundfloor window overlooking the Bristol Channel.
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Chris, re your query: "Michael: How's your received signal strength now compared to previously? Obviously depending on what the original cause was, it may not have changed much as it might have been primarily a westerly direction affected." - Hard to tell, Chris, as signals from Preseli, Kilvey Hill and Carmel fluctuate all the time with the 7m tidal range in the Bristol Channel - possibly at times in addition to CCI with Ilfracombe channels. To be sure of what has been happening since the retune exercise, I would have had to be squatting in the den 24/7, logging all three signals every 20 minutes :-) At this moment, 22 July 17:54, poking my Silver Sensor log out the window, 690 MHz from Carmel is ok, with some pixelation. A higher, longer rooftop yagi would doubtless behave better! Derek's postings suggest there just might have been a wee problem at the mast...
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Spanner + works : you get my drift... The prediction sites are not infallible. They cannot include very local factors, such as buildings, hills, estuaries etc. What they tell me I should receive, I don't, or unsatisfactorily. What they don't list is what I receive :-) Noting down postcodes further away and inserting them into the prediction boxes can result in interesting alternative predictions - and channels worth trying. Where more than one transmitter is in range, auto-tuning can be tortuous. Manual tuning is preferable, but in many receivers well hidden and not user-friendly. Conspiration theorists claim NASA didn't land on the moon; others claim the inimical DTT system intends to prepare us for TV by subscription via 5G. Must all be rubbish, surely???
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Chris, I dearly hope you get some info or, at least, some clues from Arqiva. We might eventually get a clearer picture of challenging DTT retune happenings. Thereafter we will be musing about 5G, which triggered the DTT retune to the lower end of the DTT spectrum. As a licenced radio amateur, I am concerned about the high level of interference from VDSL and domestic digital devices. But Ofcom ain't interested... ( Here, we currently don't get any 2-3-4G signal...) We should all be concerned about the relentless downsliding quality of TV programmes. I have kept my library of books - just in case...
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In times of high atmospheric pressure, TV and radio signals travel further. This includes "unwanted" signals from other transmitters, which can cause interference (pixellation, picture blocking etc.). If this occurs and does not disappear again when atmospheric conditions return to normal, there might be another cause. Wait and see!
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Friday 19 July 2019 11:37PM
Following the Carmel re-tune on 17 July, on a log-periodic antenna
muxes on channels 23,26,29,33 and 36 are received on the North Devon coast,
but not the mux on the higher frequency of ch 48.
The Ilfracombe relay "shares" channels 33,36 and 48 with Carmel.
Ilfracombe HD is on ch 48, so HD co-channel might be a problem.
Or is Carmel Arqiva-B on a frequency other than the announced ch 48 (690MHz),
which is surprisingly much higher than the others ?