All posts by Chris.SE
Below are all of Chris.SE's postings, with the most recent are at the bottom of the page.
Nicholas Anderson:
At present the BBC have said BBC4 HD will return to Freeview, but haven't specified a timescale. This is believed to be due to equipment delivery delays from outside the UK.
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All:
As the listings at the top of this page aren't fully updated, for the sake of clarity, here is the current data -
In the multiplex order BBCA/PSB1, D3&4/PSB2, BBCB HD/PSB3, SDN/COM4, ArqA/COM5, ArqB/COM6
Oxford UHF channels are -
The main multiplexes are C41, C44, C47, C29, C37, C31
The Local mux L-OFD is on C22.
Note - COM7 has now closed.
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Michael Martin:
As you undoubtedly know from previous posts, a full postcode would be required to give the most likely reception conditions at your location. In your general locale the most likely transmitter will be Oxford at a bearing of approx. 38 degrees (almost NE), rods horizontal. Have a look at your neighbours aerials!
The Oxford page has UHF channel details.
Depending on location, you may get some very weak signals of some multiplexes from Crystal Palace and/or Sandy Heath, but they will be very unreliable.
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Aerialman:
Thanks for pointing out the extra petal for the Oxford Local mux. I recall seeing it mentioned in an OFCOM document I read some 18months+ ago but had forgotten since.
According to OFCOM and Freeview/DUK documents it is actually on UHF C46 (not 40) and beams due E.
The petal on C22 beams both NW and a little less to the SW.
Both petals use 10kW each.
I'm not sure that "decided" is the right word for the lack of some site updates by the owner, I think it's more a case of not having had sufficient time, as you probably know there are over 1100 transmitters in the UK many of which had changes with the 700MHz clearance. I know that updating is a tedious job because the updates from OFCOM documents have to be entered into the database manually as the source documents are all .pdf so not a task I would relish!
Nevertheless it is rather a shame that there hasn't been some progress on updating at least the 80+ main transmitters where needed. I know the site owner has been in hospital recently with pneumonia which obviously isn't helpful to the cause.
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Glyn Hammond:
Before you rush off to get an amplifier, what is the state of your coax?
How long ago was the aerial replaced? Was the coax replaced at the same time with quality double screened (eg.CT100 standard) coax?
If it's old coax and there's been any ingress of water at anytime, if the outer sheath has become brittle etc. this will all affect the signal at the set. Certain problems can cause "standing waves" in the coax which can be specific to one frequency, and maybe in your case affect C47. Other problems can just cause severe attenuation especially the higher frequencies.
Were you getting the HD multiplex before the aerial was replaced? If so, I'd be having a close look at the coax if it wasn't replaced. If it was, a thorough check of all the connections.
If you've never had the HD multiplex then may interference could be an issue. Check you haven't got any older equipment (eg.VCR's etc) with RF output operating below C47.
I take it you haven't got any splitters for providing signal to more than one device.
Even though a signal strength reading at the set of 51 for C44 seems low, I'm surprised that it's all 0 at C47.
Should it turn out to be a case of needing an amplifier, make sure it's one with a variable gain control. Too much signal can also cause problems, especially if there are any mobile masts nearby. I would be trying to get a filter from restoretv.uk in any event.
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Glyn Hammond:
Connect the aerial direct to the TV and see what signal strength and quality you get on each channel.
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Glyn Hammond:
With that drop in signal between C44 and C47, I would be looking at replacing the coax from the aerial to the splitter position, and from the splitter to any TV where there's an external run or the coax sheath is looking degraded.
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Ted Slater:
Hello Ted. Hmm. I come back to a remark I made to an earlier post about the strength dropping with increasing channel number (and therefore increasing frequency) and that pattern exists without the distribution amp/splitter and you've confirmed that the filter is making no difference to the figures.
This would seem to suggest that it's not interference, but some issue with the aerial end. As the aerial is in the loft, then water ingress isn't a likely cause either.
The thing I notice with this last set of results is that the strength is now lower than a comparable set of figures a while ago, and we've just had a period of extremely hot weather where metal joints are most likely going to be affected. As much as it might have seemed unlikely, I'm thinking it's some fault with the aerial, either the connector box to the dipole itself, or if there's a balun, to the balun or balun to dipole or the balun itself.
You say this is a 10 element aerial, roughly how old? Is it a "conract" type with a small metal grid on the back or does it have a few rods as a reflector?
If you know what it is, or it's gain that'd be helpful. But I'm coming to the conclusion, especially if stairs are an issue, that it would be simpler to just replace the aerial.
You don't need anything elaborate considering your proximity to the transmitter etc. so expensive large multi-element aerials are not needed, but maybe something with just slightly better gain than what you have at present. There are quite a few reasonable "K" group aerial about, but as you have a filter a "T"/Wideband would probably do.
What more can you tell us about the existing aerial? (And the amount of space in the loft where it is?).
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Dave Barter:
It's most likely to be the current weather conditions producing some temperature inversion/tropospheric ducting which can affect different parts of the country at different times. Both Freeview and the BBC have current warnings about the possibility over the next day or two.
The affects can be brief or more prolonged, often affecting only one multiplex but sometimes several. Do NOT retune!
See Channel listings for Industry Professionals | Freeview for which channels are carried on which multiplex.
You'd need to quickly flick to another channel on the ArqA/COM5 multiplex to see if any of those were affected in the same way as already mentioned other multiplexes may not be affected at the same time or to the same degree.
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Sunday 17 July 2022 3:40PM
John Simmons:
Whilst current weather conditions can disrupt reception with signals from distant transmitter in the UK or Europe causing interference (Freeview and the BBC had issued warnings) reception in your area is unlikely to be affected at this particular moment (doesn't mean it won't be!).
I take it from your remarks that you probably haven't retuned, but DON'T as this will probably clear your correct tuning if done when you have no signal.
If perchance you have retuned, then
I suggest you do a MANUAL tune on the UHF channels for the multiplexes you are missing (list right at the top of the page, remembering COM7 has now closed).
The transmitter has been the subject of Planned Engineering, and there's a possibility that some work may be continuing, it's unusual for individual multiplexes to be off-air or low power for any length of time.