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Full Freeview on the Divis (Northern Ireland) transmitter

first published this on - UK Free TV
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The symbol shows the location of the Divis (Northern Ireland) transmitter which serves 440,000 homes. The bright green areas shown where the signal from this transmitter is strong, dark green areas are poorer signals. Those parts shown in yellow may have interference on the same frequency from other masts.

Are there any planned engineering works or unexpected transmitter faults on the Divis (Northern Ireland) mast?

Divis transmitter - Divis transmitter: Possible effect on TV reception week commencing 17/06/2024 Pixelation or flickering on some or all channels Digital tick

Choose from three options: ■ List by multiplex ■ List by channel number ■ List by channel name

Which Freeview channels does the Divis transmitter broadcast?

If you have any kind of Freeview fault, follow this Freeview reset procedure first.

Digital television services are broadcast on a multiplexes (or Mux) where many stations occupy a single broadcast frequency, as shown below.

 H max
C27 (522.0MHz)551mDTG-100,000W
Channel icons
1 BBC One (SD) Northern Ireland, 2 BBC Two Northern Ireland, 9 BBC Four, 23 BBC Three, 201 CBBC, 202 CBeebies, 231 BBC News, 232 BBC Parliament, plus 14 others

 H max
C21+ (474.2MHz)551mDTG-100,000W
Channel icons
3 UTV (SD) (UTV), 4 Channel 4 (SD) NI ads, 5 Channel 5, 6 ITV 2, 10 ITV3, 13 E4, 14 Film4, 15 Channel 4 +1 NI ads, 18 More4, 26 ITV4, 28 ITVBe, 30 E4 +1, 35 UTV +1 (UTV),

 H max
C24 (498.0MHz)551mDTG-100,000W
Channel icons
46 5SELECT, 101 BBC One HD Northern Ireland, 102 BBC Two HD Northern Ireland, 103 UTV HD (UTV), 104 Channel 4 HD NI ads, 105 Channel 5 HD, 106 BBC Four HD, 107 BBC Three HD, 204 CBBC HD, 205 CBeebies HD, plus 1 others

 H -3dB
C23 (490.0MHz)551mDTG-850,000W
Channel icons
20 Drama, 21 5USA, 29 ITV2 +1, 32 5STAR, 33 5Action, 38 Channel 5 +1, 41 Legend, 42 GREAT! action, 57 Dave ja vu, 58 ITV3 +1, 59 ITV4 +1, 64 Blaze, 67 TRUE CRIME, 68 TRUE CRIME XTRA, 78 TCC, 81 Blaze +1, 83 Together TV, 91 WildEarth, 93 ITVBe +1, 209 Ketchup TV, 210 Ketchup Too, 211 YAAAS!, 267 Al Jazeera English, plus 30 others

 H -3dB
C26 (514.0MHz)528mDTG-850,000W
Channel icons
11 Sky Mix, 17 Really, 19 Dave, 31 E4 Extra, 36 Sky Arts, 40 Quest Red, 43 Food Network, 47 Film4 +1, 48 Challenge, 49 4seven, 60 Drama +1, 65 That's TV 2, 70 Quest +1, 74 Yesterday +1, 75 That's 90s, 233 Sky News, plus 11 others

 H -3dB
C30 (546.0MHz)528mDTG-850,000W
Channel icons
12 Quest, 25 W, 27 Yesterday, 34 GREAT! movies, 39 DMAX, 44 HGTV, 52 GREAT! romance, 56 That's TV (UK), 63 GREAT! romance mix, 71 That’s 60s, 73 HobbyMaker, 82 Talking Pictures TV, 84 PBS America, 235 Al Jazeera Eng, plus 18 others

 H -13dB
C36 (594.0MHz)528mDTG-125,000W
Channel icons
from 29th September 2014: 7 NvTv,

 H -40dB
C48 (690.0MHz)551mDTG-10W
Channel icons
from 4th September 2019: 53 TG4, 54 RTÉ One, 55 RTÉ Two,

DTG-8 64QAM 8K 3/4 27.1Mb/s DVB-T MPEG2
DTG-12 QSPK 8K 3/4 8.0Mb/s DVB-T MPEG2
H/V: aerial position (horizontal or vertical)

Which BBC and ITV regional news can I watch from the Divis transmitter?

regional news image
BBC Newsline 0.6m homes 2.5%
from Belfast BT2 8HQ, 1,044km northeast (51°)
to BBC Northern Ireland region - 46 masts.
regional news image
UTV Live 0.6m homes 2.5%
from Belfast BT7 1EB, 1,044km northeast (51°)
to UTV region - 46 masts.

Are there any self-help relays?

Chapel FieldsTransposerCentral Belfast61 homes

How will the Divis (Northern Ireland) transmission frequencies change over time?

1950s-80s1984-971997-981998-20122012-134 Mar 2020

tv_off Being removed from Freeview (for 5G use) after November 2020 / June 2022 - more
Table shows multiplexes names see this article;
green background for transmission frequencies
Notes: + and - denote 166kHz offset; aerial group are shown as A B C/D E K W T
waves denotes analogue; digital switchover was 10 Oct 12 and 24 Oct 12.

How do the old analogue and currrent digital signal levels compare?

Analogue 1-4 500kW
BBCA, D3+4, BBCB(-7dB) 100kW
SDN, ARQA, ARQB(-10dB) 50kW
com8(-16dB) 12.7kW
com7(-16.1dB) 12.4kW
LBT(-20dB) 5kW
Mux 1*, Mux 2*, Mux A*, Mux B*(-23.4dB) 2.3kW
Mux C*(-24dB) 2kW
Mux D*(-24.9dB) 1.6kW
NIMM(-47dB) 10W

Which companies have run the Channel 3 services in the Divis transmitter area

Oct 1959-May 2006Ulster Television
May 2006-Dec 2014UTV plc
Feb 1983-Dec 1992TV-am•
Jan 1993-Sep 2010GMTV•
Sep 2010-Dec 2014ITV Daybreak•
• Breakfast ◊ Weekends ♦ Friday night and weekends † Weekdays only. Divis was not an original Channel 3 VHF 405-line mast: the historical information shown is the details of the company responsible for the transmitter when it began transmitting Channel 3.

Thursday, 24 October 2019

2:32 PM

Because when I switched my own LED downlighters off the noise went down considerably!
The QRN seems to be type-specific to MR15 LEDs. I have now changed them out for GU10 230V ones, which gave no noise with a portable radio (on an empty VHF frequency) held close to the base. The noise seems to have been radiated from the lamps themeselvs and not through the mains wiring. The (separate) SMPSU's could have been part of, or the, problem as they were designed for halogen filament loads (one burnt out). In any case the safe and cost effective solution was to bin the lot and fit GU10s.

Although the noise problem in my flat has largely been solved for the VHF band there is still noise especially in the evenings, so I suspect from a neighbour. My own MR15s blocked next door's VHF too!

Anyway I tested all my other LED lamps (ES and BC) and none of them are noisy. I only tested on the VHF FM band and there is much noise on HF, hence my interest in the spectrum analyser dongle.

I hadn't noticed that about filamentary type LED bulbs, I guess they drop the voltage by lots of LEDs being in series.

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Denis's 24 posts GB flag
Denis's: mapD's Freeview map terrainD's terrain plot wavesD's frequency data D's Freeview Detailed Coverage
Tuesday, 3 March 2020

10:11 PM
Newcastle Upon Tyne


A reminder that there's a retune event on Wednesday 4th March. the transmitter is likely to go off-air shortly after midnight. COMs 7&8 are moving to UHF channels 55 & 56 with a power change to 8.9kW for each mux.
PSBs1-3 & COMs 4-6 are on C27, C21, C24, C23, C26, C30 no change, no power change.
The NI mux is on UHF C48, and the Local Belfast mux is on C36.

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Chris.SE's 4,243 posts GB flag
Chris.SE's: mapC's Freeview map terrainC's terrain plot wavesC's frequency data C's Freeview Detailed Coverage
Monday, 16 March 2020
Ivan McLorn
7:46 PM

Chris.SE: I live in BT67 area and had no problems with signal strength prior to your works on 4th March but since this date ITV signal fluctuates and sometimes disappears completely. I have found that channel 3 appears to have better signal strength than103.
Is this some problem at my end or is there still ongoing works at the Divis transmitter?

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Ivan McLorn's 1 post GB flag

10:29 PM

Ivan McLorn:

Hi Ivan, first to say, it wasn't "our" works, this is an independent help-site. The changes are made by Arqiva who maintain the transmitters, on behalf of Freeview/DigitalUK.

The only changes at Divis was the move of the COMs 7&8 multiplexes to C55&C56 so you shouldn't have seen any other issues. There's no listed Planned Engineering at Divis this week (so we must assume there isn't anything going on).

I'm wondering that perhaps if you retuned when the transmitter didn't have all multiplexes running that you may have got tuned to another transmitter. Check in your TV's tuning section that the UHF channels for each multiplex are those as listed in the post before yours.

If you aren't sure/unable to do that, one of the easiest solutions might be to retune as follows -
Unplug the aerial and carry out a full automatic retune - this should clear all previous tuning as no channels should be found. Then plug the aerial back in and repeat the retune. Hopefully this will restore all channels correctly.
If you still have problems, post back, preferably with some detail about UHF channel, signal strength and quality for each multiplex from your TV's tuning section.

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Chris.SE's 4,243 posts GB flag
Friday, 20 March 2020
Denis Campbell

5:49 AM

Sinead: To add to Dave's good advice...
The re-broadcast RTE from Black Mountain (and some fill-in stations) has only three TV and one Radio channel. TV content is often blocked for legal reasons.
Receiving direct from Claremont Carn gets you lot more channels and no content blocking. But you will need a high-gain aerial and an aerial combiner (if you want the Freeview channels as well). Look around your neighbourhood and if you see high-gain aerials pointing south then you should get the signal. There is a gap in the Mournes that allows the signal through to parts of N.Ireland including Belfast.
I understand the channel numbers appear in the 800 range, to avoid confusion with Freeview channels.

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Denis Campbell's 24 posts GB flag
Wednesday, 25 March 2020
P. Kieran Ward

10:38 PM

Hi all! I live in North Belfast and receive my Freeview TV from the Divis Transmitter. I also get the three RT TV channels and the RT Radio channel from the Black Mountain transmitter's NIMM an UHF 48. I receive all of the other channels transmitter from the Divis Transmitter with the exception of UHF 55 which carries the multiplex COMM 7.

I can't understand how I do not receive COMM 7 - anyone any suggestions?

Also, UHF Channels 55 and 56 are due to be cleared (for Mobile Internet use) by June 2020, why are they still in use - again has anyone any suggestions? After all, Saorview Multiplexes 1 and 2 were on UHF Channels 52 and 56 from Clermont Carn Co. Louth but they cleared these two channels and moved their Multiplexes to UHF Channels 42 and 45. Why did Ofcom allow COMM 7 and COMM 8 to be moved to channels that their use for Television Transmission needs to be relinquished by June 2020 - anyone know an answer to this one also?

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P. Kieran Ward's 89 posts GB flag

11:27 PM

P. Kieran Ward: UHF channels 55 & 56 are in the centre gap of the new 700MHz mobile band and will not be required for 5G use for some time (probably another couple of years) so Ofcom have allocated those channels as the temporary home of COM7 & COM8, which will then close once the mobile networks start to use those centre gap frequencies (rather than being cleared in May like the rest of the 700MHz band). See more info from Ofcom at the link below.

Maximising the benefits of 700MHz clearance - Ofcom

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StevensOnln1's 3,647 posts GB flag
Thursday, 26 March 2020

12:46 AM

P. Kieran Ward:

In addition to what StevensOnln1 has said, a reminder that you were advised last May that the channel clearances and future usage was a co-ordinated change between Saorview and Freeview. Perhaps it should also be said that all these changes have been made as a consequence of European agreements (not just a decision by OFCOM), Europe has been making similar changes. (Also it should be remembered that general frequency usage is also subject to International agreements).

Also UHF55&56 were not "due" to be cleared (for Mobile Internet use) by June 2020, it was just a date that OFCOM were proposing, however Arqiva had always opposed this date, and nothing definitive was ever made public. The 700MHz frequencies haven't been auctioned yet, so there is unlikely to be any clear information available in the immediate future.

You may be aware that the DigitalUK site which we've referred to many times in the past for predictions and other technical information was merged into the Freeview site at the end of last October. Because of the poor way that this was done it's currently not possible to link directly to urls for predictions, but if you explore the site you can manage to extract most of the useful UK information - it's not especially user friendly IMHO.
If you goto Freeview | All your favourite TV shows, all in one place and all for free and put your postcode and house name/number into the box just down the page, then on the new page scroll right down and click "Detailed view" you can then look at the prediction for reception at your location.

You may find that predicted reception for COM7 is not as good as COM8. COM8 had a UK wide FEC change to 1/2 on the 10th Feb. for all transmitters that are using UHF56 (which I think is all of them now that transmit COMs7&8 IIRC). Because of the SFN nature of these muxes this also had the effect of changing hot and not spots and the signal strength seemed to increase in a number of areas, whereas COM7 was not affected.
If you are "technically" outside the coverage area, you may have to make some clever adjustments to your aerial installation to possibly receive everything satisfactorily.

You may also notice that the Freeview Detailed Coverage Checker is now showing the "Final Prediction" as 2025 for all multiplexes including those transmitters with COMs 7&8. So it's now speculation that they may continue until 2025. It's also speculation (and been said previously) that sometime between now and then, probably a bit nearer then, that one (maybe eventually more) of the other COM muxes will convert to T2 allowing for a move of (some of) the HD programmes. No doubt when something definitive is announced by OFCOM and/or Arqiva, people will post links to the information. HTH.

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Chris.SE's 4,243 posts GB flag
Saturday, 22 August 2020
denis campbell

1:40 PM

Belfast Black Mountain NIMM on Mux36 broadcasting RTE Channels.
The transmitter is listed as being 5kW, but I think it must be higher as I receive it in Killyleagh (20 miles away) at 82% (arbitary reading on LG TV).

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denis campbell's 24 posts GB flag
Tuesday, 25 August 2020

10:55 AM

denis campbell: The NI mux is broadcast using QSPK modulation, which gives the equivalent coverage to the main multiplexes, but uses less power as it is a more robust transmission mode. The trade off is that there is only enough space for 3 or 4 channels, whereas the main commercial multiplexes all carry at least 15 channels.

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StevensOnln1's 3,647 posts GB flag
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