All posts by Chris.SE
Below are all of Chris.SE's postings, with the most recent are at the bottom of the page.
Mike:
Sutton Coldfield is currently listed for Planned Engineering with "Possible weak signal" so it's quite likely this may be the cause of the problem you are seeing.
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cairns:
As you have posted on the Alexandra Palace transmitter page, there would be an assumption that normally you might be tuned to it. That said there are no reported problems that I can find for Alexandra Palace.
However, that said, depending exactly where you are within your postcode, higher street numbers are showing not only a slightly better prediction for Alexandra Palace but significantly better predicted reception for Crystal Palace. From your locale, both transmitters are easily within the beamwidth of your aerial.
If you normally receive the full list of available channels, see Channel listings for Industry Professionals | Freeview which also tells you which channels are on which multiplex (group of channels), then you will be picking up Crystal Palace
So you may be tuned to Crystal Palace which is currently listed for Planned Engineering, and was also listed before and just after Christmas with "Possible weak signal", this might account for your problems. Alexandra Palace is a relay of Crystal Palace so might have been affected at some point by the engineering work.
If you retune when you have weak or no signal, often it just clears the correct tuning, you can end up incorrectly tuned to other transmitters with weaker signals etc.
Again, depending on your precise location, predictions show several other transmitters might be received in the "wrong" (weather) conditions. So what does this all mean. You'll need to retune BUT do it manually in the manner I'll explain.
It'll be a good idea to start by checking that your aerial is still pointing in the correct direction and appears undamaged and similarly your downlead. The aerial should be pointing at a bearing of between 167 degrees for Crystal Palace and 173 degrees for Alexandra palace, ie between about 13 degrees and 7 degrees E of due South. If need be, also check all your coax plugs, connections, flyleads etc, unplug connectors check for corrosion or other problems and reconnect them. Flyleads are a common problem, try swapping/changing them. See what signal strengths and quality you are getting for the multiplexes (groups of channels) shown in your TV's tuning section.
Problematic connections, water ingress etc. can seem to affect reception of just AN individual or several multiplexes. Also make sure you don't have any HDMI leads near unscreened/poorly screened flyleads/aerial leads as that can cause interference.
Ok, retune as follows. First unplug the aerial and do a full automatic retune which should clear all existing (and possibly incorrect) tuning.
You now need to try a manual tune (look for Manual Tuning in the TV tuning section) on the following UHF channels listed in the following multiplex order -
BBCA/PSB1, D3&4/PSB2, BBCB HD/PSB3, SDN/COM4, ArqA/COM5, ArqB/COM6, COM7 (HD), Local.
For Crystal Palace - C23, C26, C30, C25, C22, C28, C55, C35
OR for Alexandra Palace - C31, C32, C37 (PSBs only here).
It will depend on your aerial installation which you can get, and if your receiver doesn't have a T2/HD tuner, ignore PSB3 and COM7. You might find that you'll be better tuning to Alexandra Palace for the PSB multiplexes and Crystal Palace for the remainder if Crystal Palace signals appear unreliable. BUT too strong a signal from Alexandra Palace may cause Crystal Palace signals to pixellate, so you might have to try to find a good balance. Sorry if this all sounds complicated.
If you can get PSB3 but not COM7 it may be you have an old Group A aerial. It may not be worth the expense of replacing as COM7 is a temporary multiplex and will close in due course at the latest end of June 2022. If the aerial needs replacing for other reasons then a Group T/Wideband is needed to get all multiplexes BUT your location might mean you'd be better with a Group A aerial to get the other COM multiplexes reliably. An aerial installer with good knowledge of your area would know. Also see what your neighbours get.
The above should enable you to resolve the problem, but bear in mind Crystal Palace is still listed for Planned Engineering at present. If you still have problems, post back with more details about your aerial installation, any splitters etc. and which multiplexes you have problems with.
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Alex Mckenna:
Living within the M25 is no guarantee that you will automatically get good TV reception. A lot depends on the local terrain. There are a number of Relay TV transmitters in some surrounding areas of London because of that.
That said, your locale should generally be within good coverage of the Crystal Palace transmitter, but local factors can affect that - trees, hills, scaffolding on your or other very near buildings, etc. etc.
You may indeed have a problem with your aerial installation, you may be suffering from interference. Has anything changed in or near your installation or equipment in about the last 12 months?
It would be a good idea to check that your aerial seems intact and pointing in the correct direction, from your locale it should be pointing roughly at a bearing of 199 degrees, that's almost SSW, with the rods horizontal. Also check that your downlead looks undamaged and isn't flapping in the wind.
Check all you coax plugs, connections, flyleads etc, unplug connectors, check for corrosion or other problems and reconnect them. Flyleads can be a common problem, try swapping them. See what signal strengths (if any) and quality you are getting for the multiplexes shown in your TV's tuning section, this might indicate potential issues with your aerial or downlead.
Problematic connections, water ingress etc. can seem to affect reception of just AN individual or several multiplexes.
Make sure that you don't have any HDMI leads close to poor quality (ie. not double screened) flyleads and aerial leads, as that can sometimes cause interference.
If you happened to try retuning when there was no or a badly pixellated signal, this often just clears the correct tuning and you can, dependent on weather conditions end up picking up weak signals from other transmitters which can deteriorate as the weather changes. It would be an idea to check in your TV's tuning section that you are tuned to the correct UHF channels for Crystal Palace. They are, in the following multiplex order -
BBCA/PSB1, D3&4/PSB2, BBCB HD/PSB3, SDN/COM4, ArqA/COM5, ArqB/COM6, COM7 (HD), Local.
For Crystal Palace - C23, C26, C30, C25, C22, C28, C55, C35 (C means channel)
If your set doesn't have an HD/T2 tuner, you can ignore the BBCB and COM7 multiplexes.
If you need to retune, unplug the aerial first and do a full automatic retune which should clear all existing (maybe incorrect) tuning. Then plug the aerial back and ideally do a manual tune for the UHF channels listed.
If you want to know which channels are carried on which multiplex (group of channels) see -
Channel listings for Industry Professionals | Freeview
If you provide a full postcode, we can look at your predicted reception and offer further advice including the specific direction your aerial should be pointing. If you are still having problems please provide that and more detail about your aerial installation, any splitters, & etc.
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Peter Green:
It's because part of the 700MHz clearance was to move COM7 to C55 if it wasn't there before, ie on Winter Hill it was on C31. COM8 would have still been on C56 except Arqiva closed it for commercial reasons back at the end of last June.
C55 operates from 25 main transmitters around the country as an SFN. It is and always was a temporary mux. C55 (& C56) are in the "centre-gap" of the frequencies allocated for Mobile Download and Upload in the 700MHz band. The "centre-gap" is allocated for mobile SDL usage.
When the auction of the 700MHz band takes place IF any MNOs buy the SDL frequencies, when they have developed the necessary equipment to use it, they may give 3 months notice for C55 to close. In any event it will close at the end of June 2022 if not before.
For detail about COMs 7&8 see Rebuilding Freeview High Definition from 2019 onwards | free and easy
As you know covid-19 disrupted the final 700MHz program but this was completed last August.
The only further update to that detail is OFCOM were planning that the auction might start later this January but I haven't checked if that is still the case.
(The initial information about rebuilding Freeview HD is somewhat speculative, AFAIK based originally on what went into the "Vaizey Plan" which never got implemented!).
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Gtibb:
Thanks for that interesting technical information. Shame we don't see more of that sort of thing around this site.
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Sarah Mckinney:
Did you have a TV set connected previously? If so, which TV region were you getting?
Which way is your aerial pointing?
If more or less due N as mentioned by StevensOnln1, there are two Anglia region transmitters you might receive, one is stronger than the other.
If your aerial is pointing fractionally S of due W, there is certainly one, but maybe two transmitters you may get for the Meridian region (again one is stronger than the other, but reception of some multiplexes may be variable).
If your aerial is pointing fractionally N of due W, you may be getting the London region, reception of most multiplexes will be variable.
Indeed if your aerial points generally W, all those transmitters in that general direction may be receivable as they'll be within the "beamwidth" of your aerial, you may have to resort to manual tuning to get the region/signals you want reliably BUT that's only once you are getting some signals from your booster as explained by StevensOnln1.
There's one other possibility, one other Meridian transmitter if your aerial points about halfway between due E and SE, but some signals are likely to be variable or poor/zero.
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Iain Hedley:
I assume that you believe you get your TV signals from the Chatton TV transmitter although you have posted on the DAB transmitter page. If you do get your signals from Chatton, it is listed this week for Planned Engineering with "Possible weak signal". Depending on your location, weak signal may seem like no signal (digital cliff edge) to your receiver. A full postcode would be needed to check predicted reception at your location and which transmitter(s) and multiplexes you might receive.
Do NOT retune whilst you have No signal or a badly pixellated picture as it often just clears the correct tuning and also you might end up tuned to a weaker than normal signal from another transmitter which will be unreliable. You'll then need to retune again when your transmitter's signals return to normal.
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Wednesday 13 January 2021 10:07PM
peter:
I can't find any reports of problems affecting ArqB/COM6 and the transmitter isn't currently listed for Planned Engineering.
Is the problem still present? Are you receiving COM7 C55 ok?
It might be worth checking that your aerial seems intact and pointing in the correct direction (at your location bearing 124 degrees - that's 11 degrees E of SE with rods horizontal) and that your downlead looks undamaged (especially if it is old).
Also check all your coax plugs, connections, flyleads etc, unplug connectors check for corrosion or other problems and reconnect them. Flyleads are a common problem, try swapping/changing them. See what signal strengths and quality you are getting for the multiplexes (groups of channels) shown in your TV's tuning section.
Problematic connections, water ingress etc. can seem to affect reception of just AN individual or several multiplexes.