All posts by Chris.SE
Below are all of Chris.SE's postings, with the most recent are at the bottom of the page.
RBZ5416:
COMs 7/8 were always only ever temporary HD multiplexes and COM7 is now only currently broadcast from 25 main transmitters. COM8 closed in June 2020 primarily for commercial reasons influenced by the pandemic, and COM7 is scheduled to close at the end of June 2022 under the terms of the current OFCOM licence.
There's been no announcements about what will happen to any of the channels on COM7. There's lots of speculation but no facts!
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Brian Richardson:
If the aerial is very similar to that link which did appear in the first post it looks like a standard 10 element Yagi.
Do the elements in front of the dipole look fairly equi-spaced and equal length?
If so, I'm going to guess it's an old Group C/D aerial which was Pontop Pike's Group before the 700MHz Clearance program when all the multiplexes were on the high UHF channels.
Have a look with some binoculars (or telescope!) and see if it's a Green plastic plug in either end of the boom.
Since 700MHz Clearance, Pontop Pike is Group T (Wideband would do) is you include COM7, otherwise it's Group K (as an aside some decent group K aerials have sufficient gain for UHF C55).
If the elements at the end of the boom are much shorter than the ones nearest the dipole and spacing between them changes, it could be wideband but I'm sceptical from those strength figures you've posted especially C55, C45 and C42.
Group C/D aerials will not respond well to the lower UHF channels now used by Pontop Pike, although strangely I've come across some 10 element contracts that do reasonably well on C32 but have a quite uneven response up into the low 40s. Things are not helped in this situation as it's COMs4-6 on these channels and they are half the transmitted power of the PSBs at Pontop Pike.
Under normal conditions you should get very good reception from Pontop Pike (leaving aside the possible aerial query at present). The current "tropo" conditions may clear for a while Sunday a.m but according to 2 different predictions they're like to return Sunday p.m. and this could continue through Monday, Tuesday and into Wednesday a.m.
If you can post some more of the strength and error figures for all muxes during Sunday a.m. that might give a further feel for things.
Essentially what happens with the "tropo" is, it can/often will be frequency dependent, and depending on where interfering signals are coming from, which UHF channels will be affected. Whilst the interference isn't too strong, you might see an increase in the strength figures but the error (or quality) figures get worse. But beyond a certain point, the strength figure can drop as the set eventually sees the combined interference and wanted signal as just noise and if the set sees zero signal it may see no errors. If the interfering signal gets strong enough , the strength could be good and errors low you might find a different multiplex on the UHF channel if you were to retune - not advised (unless you want to go dxing of course) - if you upset your correct tuning you don't know when things return to normal and you have to keep retuning to find out. Confusing!
There are a number of powerful transmitters to the south of you and further afield in France, it'll depend on conditions at the time as to which ones might interfere. E.g. hypothetically if you were to find a good signal with low enough errors on C34 but your usual COM5 channels were blank, if a retune of C34 gave ITV West (it may get put in the 800s as you have LCN3 etc already tuned) then the signal would likely be PSB2 from Mendip (Somerset).
Anyway, strength and error figures when there's no tropo will give a guide as to a way forward.
But there's one thing you can check when convenient, as the 2-way booster is in the loft, you could check the coax to the aerial with a meter (or maybe bulb and battery if you don't have an ohm-meter) - a check between centre core and sheath should appear short/very low resistance because of the folded dipole. It doesn't distinguish between this and a plain short on the coax, but you probably wouldn't have as good a signal across the muxes if it was a plain short. If it's open circuit, it's likely a break in the centre core but strangely it doesn't mean no signals get through but they won't be the strength they should be.
Does the 2-way booster have variable gain, what model is it?
Another experiment you can try if you have time when there's no "tropo" - couple the aerial direct only to the coax for your main TV (ie. no booster) and see what signal & error figures you get.
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jack:
Hi jack. Thanks for the update. Now that's interesting about C26. There's those unfortunate "tropo" weather conditions around again with the high pressure (although it's predicted to be mostly clear Sunday a.m. but returning Sunday p.m.) so I'm suspecting C26 has been "wiped-out" by interference from another transmitter signal on C26. When the normally received signal and interfering signal get to a certain point, they appear to be just noise to the set - ie. no signal.
I still suspect that your previously received C26 was PSB1 from the Wrekin, especially if you eventually identified it as Freeview West Midlands.
COM7 is pretty much always the most vulnerable mux being lower power and an SFN when you aren't ideally sited. Your trees wont' be helping.
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Derek:
As the site owner hasn't had time to update the errors, I posted this (one of many) just over 12 months ago -
In the multiplex order BBCA/PSB1, D3&4/PSB2, BBCB HD/PSB3, SDN/COM4, ArqA/COM5, ArqB/COM6, COM7, Local multiplex, the UHF channels for Crystal Palace are as follows
C23, C26, C30, C25, C22, C28, C55, C35 (London Local mux).
See Channel listings for Industry Professionals | Freeview for which channels are carried on which multiplex.
Worth repeating now and again for those that aren't aware.
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Ally:
In addition to what StevensOnln1 has said, it might be helpful if you could say which way (rough compass bearing) your aerial is pointing and whether its rods (or squashed Xs) are horizontal or vertical. You may be able to receive several transmitters and may not be getting signals from the one you thought you were.
Some transmitters were on Planned Engineering before Christmas and at other times weather conditions were affecting reception for some.
Currently, weather conditions (temperature inversion/tropospheric ducting) with the high pressure are causing interference for some at various times.
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Bob Loader:
In normal circumstances you should get very good reception from Sutton Coldfield, however there is most likely a combination of factors periodically upsetting reception at present. Current weather conditions (temperature inversion/tropospheric ducting) accompanying the high pressure system is causing interference to signals now and again, in addition to which the transmitter has just been listed for Planned Engineering which may affect signals. Not forgetting that (the temporary) COM7 is transmitted at just over a quarter of the power of the other multiplexes at Sutton.
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Reluctant payer:
FYI, AIUI, the "licence fee" is frozen for the next two years and isn't due to end until 2027 under these proposals.
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John Pykett:
Your intermittent loss is most likely due to current weather conditions. Unfortunately temperature inversion/tropospheric ducting is accompanying the high pressure weather system causing signals from distant transmitters in Europe or the UK to affect reception of wanted signals. COM7 can be more vulnerable than some multiplexes due to operating as an SFN and at lower power than most of the other multiplexes, but it is very much depends on location. Freeview and the BBC have current warning about potential intermittent disruption to reception. Do NOT retune.
There are no faults or Planned Engineering currently listed for Waltham.
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Kim Rahbek:
It's likely to a combination of factors. Unfortunately weather conditions again - see the post before yours, applicable again and it's reference to an earlier post if you'd like more detail of this type of problem.
Sandy Heath has also been listed for Planned Engineering this week, so some of that may disrupt reception.
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Saturday 15 January 2022 3:40PM
Brian Richardson:
Hi. A couple of things, first this site has a bug, occasionally you get a fatal error message and also posts take a while to appear. Just ignore that but make sure you have a text copy of what you are trying to post and wait a short while to see if the post then appears. I'm hoping the site owner will get this fixed, it's a pain!
Pontop Pike has just been listed for Planned Engineering, they don't give detail, so "why" is an unknown.
Recent weather conditions with the current high pressure won't have helped either, temperature inversion/tropospheric ducting has been having an impact at various times across the UK in the last couple of days. The BBC and Freeview currently have warnings about interference to reception.
I want to look at a couple more things, so I'll post this and come back later with a bit more explanation and further suggestions.