C48 (690.0MHz) before switchover
The map below shows all the transmitters in the UK using C48 before digital switchover started. Please click the icon to see the coverage area, and double click for more information.
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What do the map symbols mean?
BBC One region, BBC TWO, ITV plc region, Channel 4, Channel 5, Multiplex 1, Multiplex 2, Multiplex A.Before switchover
Click on a selection to see the use of the frequency use before switchover:C21 C22 C23 C24 C25 C26 C27 C28 C29 C30 C31 C32 C33 C34 C35 C36 C37 C38 C39 C40 C41 C42 C43 C44 C45 C46 C47 C48 C49 C50 C51 C52 C53 C54 C55 C56 C57 C58 C59 C60 C61 C62 C63 C64 C65 C66 C67 C68
Switchover complete
Click on a selection to see the use of the frequency use when switchover is complete:C21 C22 C23 C24 C25 C26 C27 C28 C29 C30 C31 C32 C33 C34 C35 C36 C37 C38 C39 C40 C41 C42 C43 C44 C45 C46 C47 C48 C49 C50 C51 C52 C53 C54 C55 C56 C57 C58 C59 C60 C61 C62 * * * * * *
Monday, 28 August 2023
Tuesday, 29 August 2023
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Chris.SE1:48 AM
Fiona Beattie:
Those 0% Quality figures usually indicate presence of interference. Your BT box must be coping better than the Aura in these conditions. Let's hope restoretv send you a filter quickly so we can see if that fixes the issues.
The filter should be fitted between the aerial and the first device in any chain - amp/splitter or box/set etc.
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Tuesday, 5 September 2023
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Steve Donaldson8:31 PM
Fiona Beattie: I have some further thoughts and information. As I'm not in the area, I am going by information online.
The Freeview Detailed Coverage Checker which predicts what signals may be received by postcode doesn't seem to show the high-power NI Mux from Black Mountain. I tried several postcodes in Belfast at which I expect that it is possible to receive the signal well and it did not appear once, not even indicating poor reception. I therefore think it has been missed off the Coverage Checker. Thus, that it doesn't appear for your postcode, I can't be sure whether it might or might not be available where you are.
I think the C48 signal you are receiving may be from the Whitehead relay transmitter, not Divis. Whitehead is nearly 90 degrees clockwise from the direction your aerial is pointing, plus it is a vertically-polarised signal. Your aerial is horizontally polarised to suit Divis. If I am right, it may be a wonder you are receiving it at all. The Freeview Coverage Checker suggests reception of C48 from Whitehead may be possible at your postcode. That said, Carnmoney Hill is also on C48, so I wonder if the two are acting in tandem for you (and you are receiving a bit of both). This is just a suspicion. Carnmoney Hill, while also vertically polarised, is obviously anti-clockwise of Whitehead and therefore closer to the front-facing direction of your aerial than Whitehead.
Try manually tuning the NI Mux signal from Black Mountain, which is on C33 (as DVB-T2). As before, clear the tuning memory by doing a tuning scan with the aerial unplugged, then try tuning in just C33. When you manually tune, enter/select the channel number and give it time for the signal strength and quality to settle, particularly if the signal isn't good enough to tune to the channel. If you can tune it in, see if RTE One is watchable or not.
On 4 September 2019 channel changes occurred at various transmitters in Northern Ireland, this to clear UHF channels 49 to 60 of TV (the "700MHz Band"). All transmissions in that range were moved down, all TV now in the 21 to 48 range. At the same time, the NI Mux expanded with a power increase at Black Mountain and extra transmitters. In County Antrim, it launched on C48 at Whitehead (2.4W) and Divis (10W). It is also transmitted on C48 (16W) from Carnmoney Hill, which it did prior to the 700MHz Band Clearance (meaning there was no change there).
The highest-power transmitter for the NI Mux is Black Mountain, and therefore it covers the widest area. It is near Hannahstown, at the south end of the high ground on which the two transmitters sit. With the Divis NI Mux being such low power as 10W, and with the Digital UK Industry Briefing of August 2019 describing it as "parts of Belfast only", I don't think it likely that it is reaching you in Bangor. My guess is that its purpose is to cover the area that Black Mountain doesn't reach, which I guess would be to the north and north east of the Divis transmitter, as the high ground is likely to be casting a shadow for the Black Mountain signal.
Also on 4 September 2019, the Black Mountain transmitter NI Mux changed channel from C39 to C33, with a power increase from 2,000W to 3,000W. Were you able to receive the NI Mux before 4 September 2019? If so, do you know whether it was on C39?
In terms of DVB-T versus DVB-T2, there are two DVB-T2 multiplexes: PSB3, which carries HD channels, BBC One HD etc. (C24 from Divis), and the NI Mux which you have on C48 and is also transmitted from Black Mountain on C33. All other multiplexes are DVB-T.
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Friday, 8 September 2023
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Fiona Beattie11:39 AM
Filter from restore tv didn't help. V frustrating. I'll have to cal them again
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Steve Donaldson11:54 AM
Fiona Beattie: What firmware version is your Humax Aura running? See if it is the latest one.
SUPPORT | HUMAX-United Kingdom
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Chris.SE2:22 PM
Fiona Beattie:
Hi. Current weather conditions may not be helping either. There's very variable strong "Tropospheric Ducting" around at present affecting various parts of the UK (inc. NI). This causes interference from more distant transmitters as signals travel further interfering with the wanted signal. This should settle down when the weather changes, this may change the situation.
However, I can't help thinking that whatever the source of interference, to consistently have the problem with the same one TV channel suggests something a bit more complicated. As Steve suggests check the current firmware.
There's also still some bugs in the EPG which don't seem to have a widespread effect (not which been observed) but might be the reason. Steve mentioned an issue that was affecting several other DVD recorders but that one was fixed.
IIRC there was another poster a while ago with a similar problem but in a different region and a different TV Channel, but it was the same problem, channel missing from the EPG, and that was also a Humax Aura! I'd suggest that Humax need to be investigating the issue with Freeview in much more depth.
One thing I've not seen mentioned (which might? help with any another further ideas) are the rods (or squashed Xs) on your aerial vertical or horizontal, and which way (rough compass bearing) is your aerial pointing?
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Steve Donaldson4:20 PM
Belfast
Fiona Beattie: I am of the thinking that this is a system issue somewhere, such as a software bug. If it were to turn out to be a reception issue, such as through interference, then I will be very surprised. The screen being blank on the one channel, but the other channels on the multiplex being perfectly fine doesn't sound like a reception problem to me.
The Humax Aura is a UHD Android TV Recorder:
Aura UHD Android TV Recorder | HUMAX-United Kingdom
That the screen is blank, with no sound, while the channel appears in the EPG, I assume with its name shown, points to there to being an issue with the stream coming in on the multiplex not being shown on the screen.
Having checked that you have the latest firmware, something which I expect Humax Support probably directed you to do, the only other thing I can think is to try the same multiplex from a different transmitter if one is available are your location. The only possibility is as I have suggested, C33 from Black Mountain. I have no gauge to go by as to whether you might or might not be able to receive it where you are, the only way is to try.
Finally, I suggest you contact RTE as - unless this is a reception issue - then it appears to be a problem relating to this particular receiver and therefore potentially affecting others. I am not totally ruling out a multiplex issue, but if this is a device problem, then the broadcaster may be interested in performing their own tests and liaising with the manufacturer to get a fix.
I would explain all the steps you have taken, so as to demonstrate the methodical process you have gone through. It may be worth noting whether or not programme information for RTE One is populating the EPG, as this could provide a useful clue to those responsible for resolving the issue.
Some pointers on who to contact follow. One of the directors of the company responsible for the NI Mux is also a director at RTE.
While there is a page for contacting Reception on the RTE website, there isn't a specific email or telephone number, just the general "info" email and main switchboard number:
RT Reception Contact RT
The licensee of the NI Multiplex is given by Ofcom as:
Multiplex Broadcasting Services N.I. Limited
Murray House
Murray Street
Belfast
BT1 6DN
No other contact details or names of individuals at the company are provided. However, a search of Companies House turns up a list of appointed officers:
MULTIPLEX BROADCASTING SERVICES N.I. LIMITED people - Find and update company information - GOV.UK
There are two officers whose brief covers technical/engineering, they also being directors at RTE and TG4:
- Richard Waghorn, Director of Operations and Technology, RTE. Email: richard {dot} waghorn {at} rte {dot} ie
- Neil Keaveney, Director of Technology, TG4. Email: neil {dot} keaveney {at} tg4 {dot} ie
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Steve's: mapS's Freeview map terrainS's terrain plot wavesS's frequency data S's Freeview Detailed Coverage
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Fiona Beattie9:18 PM
Steve Donaldson: Aura firmware is up to date 00.09.21. Humax have been most unhelpful & extremely slow to respond. Yes I can see what's on & due to air on the blank channel with a black screen.I think I also tried ch 33 manually. I am certain it's a Humax issue as the Tv picks up all channels. I will try messaging RTE also. Thank for the support.
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Saturday, 9 September 2023
C
Chris.SE7:47 AM
Fiona Beattie:
I do agree that this is most likely a software bug as Steve says BUT such things can cause strange behaviour in the presence of interference or any bugs in the EPG transmission which currently exist, so I don't like to rule out things that could be having adverse effects even though they are quite unlikely. Note, I also draw a distinction between a "reception" issue and an "interference" issue.
Once the weather changes, and now as you have a filter, all the interference issues that your previous figures suggest, should disappear, so the case should become clear cut.
I will also point out again, that other EPG errors that existed more recently but were fixed, caused problems with a number of DVD recorders. That's why I don't rule out such things as possibly contributory, though I still think decent device firmware should cope with more minor issues.
One thing though that will add weight to your case with Humax is that I've now found that previous case involving a Humax Aura which was many months ago. I didn't quite recall the detail correctly, the "missing channel" was in the EPG (not missing as I thought) but was otherwise blank screen and no sound.
So an identical case to yours. Additionally the comment was "Humax didn't have an answer" and "a full reset of the box loses the current saved schedule".
So try hassling Humax again, they are obviously not taking this seriously enough to investigate properly.
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