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All posts by Chris.SE

Below are all of Chris.SE's postings, with the most recent are at the bottom of the page.


bob:

There was a fire at the Red Bee Media Playout Centre on Saturday evening. This has caused major disruption to a number of TV services. See https://cleanfeed.thetvroom.com/9502/preswatch/fire-at-playout-centre-knocks-out-tv-services/ and subsequent updates at https://cleanfeed.thetvroom.com/section/preswatch/

I've been seeing some reports that some transmitters are still missing some services, Waltham being one of them.

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https://ukfree.tv/radio/prediction/
Wednesday 29 September 2021 12:01AM

Willie Bone:

So far, I've found this http://www.muxco.com/multiplexes/morecambe-bay/
I couldn't find anything similar from Bauer.
This item seems to have the most comprehensive information
https://www.newsandstar.co.uk/news/18582761.dab-cumbria-ofcom-confirms-launch-two-radio-mutiplexes-delayed/

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BBC Four HD
Wednesday 29 September 2021 7:30PM

Peter Jannece:

Do you get other HD Channels? If so which ones?
BBC4HD is on the temporary COM7 multiplex and whether you receive it will depend upon your location and which transmitter you get signals from. We'd need a full postcode to advise on that.

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Hannington (Hampshire, England) transmitter
Thursday 30 September 2021 12:48PM

Richard Souchard:

If you provide a full postcode, we might be able to provide some comment on that. The Predicted reception database needs a postcode. Precisely which signals do you lose periodically?
Which way do neighbouring aerials point? Are they more "complex" aerials (more elements etc.)? How old is your installation, it may have deteriorated?

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jack:

Ok, lots of possibilities here now that we've got a location.
You shouldn't have any issues with any of the multiplexes as you are so close to the transmitter, and in addition because of the direction your aerial points and the coverage of Oxford and Ridge Hill, any Planned engineering at either is highly unlikely to have any effect of your COM7 reception.

Let's deal with an easy thing first. You said "Up until recently....." Have you changed anything about in your installation? Make sure you don't have any HDMI leads close to any aerial cables or flyleads, especially those that aren't high quality double screened flyleads etc. HDMI has been known to cause interference especially to C55.
Just also to mention, manual tuning is unlikely to have any effect as C55 is the only channel for COM7, and you say you don't have problems with the other multiplexes so you are presumably correctly tuned to Sutton Coldfield. Note - the Local mux for you is on C48. (C36 is beamed in a Northerly direction).

You've looked at your aerial, I assume you noted if it was intact and not missing any elements. The rods (or squashed Xs) should be horizontal and it should be pointing at a bearing of 343 degrees (very fractionally N of NNW) for your location. Is the downlead secure and not flapping in the wind? How old (roughly) is the installation?
Are there any nearby trees on the line of sight that have grown and maybe having an effect whilst in leaf?
Any scaffolding or new buildings gone up nearby especially on the line of sight?

Relays (repeaters) are of no consequence a far as COM7 C55 is concerned as it is only transmitted from 25 Main transmitters (was 30 before 700MHz clearance) - this in part was because it's only a temporary multiplex and the limitations of some transmitter antenna and suitability of otherwise redundant Tx equipment. These limitations, transmitter locations and the need to operate as a SFN on C55 means the Tx power is lower than the main multiplexes, this is why not everyone can receive it.
Some very weak signals from the Waltham transmitter may reach you (it does have COM7) and it had Planned Engineering until a couple of weeks ago, so there is a small possibility it might have some influence on your COM7 reception but I'd think it unlikely except possibly when weather conditions that sometimes come with high pressure cause signals to travel further than normal. Such conditions should now have cleared.

Now, you mentioned an amplifier (and ports - how many?) so obviously it's a distribution amp. Do you know what the gain per port is? What make/model is it? However, as you are close to the transmitter (12km) there is the possibility that you may have too much signal which can have weird effects desensitising tuner inputs, can give incorrect signal strength figures, and can cause pixellation and sound breakup, and also reductions in quality.
If you connect the aerial direct to one TV set (rather than through the amp - one where you can easily check signal strength and quality (your main set?), what signal strength and quality do you get on all the multiplexes.
Does the amp have a gain control?

You mention C26 and a signal of ~30% which could be PSB1/BBCA coming from The Wrekin transmitter, signals from it can get rather well into your area (no COM7 there though) and although it's a bit off-beam it'll be picked up quite well. You say there are no channels on it, but unless you tune it in you won't see them and they'd be the same as BBCA from Sutton Coldfield anyway. If you do tune it, it may replace your Sutton ones (less reliable signal) (or possibly put them in the 800s) so you might need to retune Sutton C43 to get the correct one back.
But the quite good strength of 30% supports the possible concern about too much signal from Sutton Coldfield.

Post back with the info, especially the Strength & Quality figures direct to one set, and we should be able to offer some more constructive comment and any suggestions.

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John Bowen :

Reception will be dependant on location, we need a full postcode to look at the predicted reception for you locale, you may not be getting a strong enough signal.

There is another possibility, your aerial connections or downlead may have degraded and water is getting in which will severely affect the signal arriving at your set. How old (roughly) is the aerial and downlead?

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https://ukfree.tv/radio/prediction/
Saturday 2 October 2021 2:21PM

Richard Owen:

I hope someone has a definitive answer, I don't (I can make guesses) , but in case it's relevant, what make and model is the receiver?

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Hi jack:

Thanks for all the additional information, it's very informative, and just what was needed.
Looking at those strength (&Q) figures for the aerial direct to the TV, overall, I was a bit surprised. Just a couple of initial comments - not especially surprising, COM7 C55 is lower power than the main multiplexes as mentioned in my previous post, the Local multiplex is also (much) lower power but because of the more resilient transmission mode it's coverage is better than you might expect but it is usually beamed. in this case to the SW and you are a bit off-beam so again the signal will be somewhat weaker.

In general the predicted reception should be excellent especially 12km from the transmitter. Your mention of trees is key to the issue here, especially if they are on the line-of-sight, and they can present significant problems. Most deciduous trees can have a different impact through the year dependent on the amount of leaf (wet weather can also add to the complexities), evergreens are more likely to give more similar effects throughout the year.

Apart from attenuating the signal (can be frequency dependant), the amount of which can depend on the proximity and tree size, as well as leaf cover, they can also cause reflections. In the analogue days this was usually apparent as picture ghosting.
DTV is much more resilient and can cope well with most of these reflections but beyond a certain point (not easily predictable and it can vary from set/brand to set) the set will see it as interference with a potential impact on quality of the wanted channels. Again, dependent on position, they can reflect signals from transmitters in other directions which can then be picked up by your aerial which wouldn't otherwise be the case.
Depending on leaf cover, signal diffraction is also another factor and this can be frequency dependant, so different channels could be affected differently.
This wouldn't be the first time someone has had issues (particularly with C55) in such circumstances with deciduous trees on the line-of-sight. The lower frequencies tend to propagate better anyway.

Because the figures were not as good as I was anticipating, I thought I'd have a look on streetview. You have a lot of large trees in your locale :o If any are on your line-of-sight, no wonder it's a problem. If any are yours and you can get them trimmed/topped it would be a good idea. If they are on public property, you might be able to hassle the local authority to get them trimmed especially if they are very close to your property and reducing any light through windows as well as being close enough to potentially damage your property - remember roots below ground are proportionate to the growth above ground!

Noting the figures on C48 suggests your set is coping well will quite low reported Q figures, is it an LG by any chance, I know a lot of LGs cope well with figures down to around 10% or so, but other brands could equally do so, one doesn't encounter these situations very often. Overall, the figures suggest the amp/distribution isn't having any adverse effect as afr as too much signal goes BUT if when you use it the Q goes below 100% when it's 100% without, then it might be worth looking at using a (variable) attenuator on the output (NOT input).

The remaining mystery is this C26 signal. Just to check, do you have any older devices with analogue RF outputs such as video recorders, game consoles, old sky boxes etc.? If so, check the channel they are tuned to and ideally tune them to above C60 is you still use them, otherwise turn the RF off.
Otherwise where exactly on your Programme Tuning and Settings menu are you seeing "no channels"? Are you sure there's nothing in the 800s (often where sets put duplicate/extra signals from other transmitters). With a Q 50-90 I would have expected some resolution of any DTV signals. It won't be anything used by "engineering".

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https://ukfree.tv/radio/prediction/
Saturday 2 October 2021 6:44PM

Richard Owen:

That was my guess. I don't know how common a problem tuner desensitising is in these circumstances which is why I asked about make and model of radio. I've not heard anyone else say they've had this, so whether it's just certain radios, I don't know.

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Steve Dowson:

According to the Freeview Detailed Coverage Checker as you are only 17km from the transmitter, you should have reasonably good reception of COM7 as well as good reception of the Local Multiplex on UHF C32 (giving That's TV East Anglia at LCN7 in your EPG, as well as a number of other commercial channels) also good reception of the 6 main multiplexes.
See https://www.freeview.co.uk/corporate/platform-management/channel-listings-industry-professionals for which channels are carried on which multiplex.

Tacolneston has been listed for Planned Engineering for the last 4 weeks (as per the post before yours) and this could affect your reception if the transmitter is on reduced power whilst any work is being done.

Your aerial should be pointing at bearing 195 degrees (almost SSW) with the rods (or squashed Xs) horizontal. Check that it's still pointing the correct way and has no missing elements. Is the downlead secure and not flapping in the wind? How old (roughly) is your aerial and downlead?
Do you have any aerial amplifier/splitter serving more than one set?

Are there any trees in the aerial direct line-of-sight at aerial height?
Looking in your TV tuning section, what strength figures and error counts are you getting for all the other multiplexes?

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