Full Freeview on the Divis (Northern Ireland) transmitter
 | Google Streetview |  | Google map |  | Bing map |  | Google Earth |  | 54.607,-6.009 or 54°36'24"N 6°0'34"W |  | BT17 0NG |
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 22/04/2024 Pixelation or flickering on some or all channels 
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Digital television services are broadcast on a multiplexes (or Mux) where many stations occupy a single broadcast frequency, as shown below.
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 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.
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?
BBC Newsline 0.6m homes 2.5%
from Belfast BT2 8HQ, 1,044km northeast (51°)
to BBC Northern Ireland region - 46 masts.
Are there any self-help relays?
| Chapel Fields | Transposer | Central Belfast | 61 homes |
How will the Divis (Northern Ireland) transmission frequencies change over time?
| 1950s-80s | 1984-97 | 1997-98 | 1998-2012 | 2012-13 | 4 Mar 2020 | ||||
| VHF | A K T | A K T | A K T | K T | W T | ||||
| C1 | BBCtvwaves | ||||||||
| C21 | C4waves | C4waves | C4waves | +D3+4 | D3+4 | ||||
| C23 | SDN | SDN | |||||||
| C24 | ITVwaves | ITVwaves | ITVwaves | BBCB | BBCB | ||||
| C26 | ArqA | ArqA | |||||||
| C27 | BBC2waves | BBC2waves | BBC2waves | BBCA | BBCA | ||||
| C29 | ArqB | ||||||||
| C30 | LBT | ||||||||
| C31 | BBC1waves | BBC1waves | BBC1waves | ||||||
| C33 | com7 | ||||||||
| C34 | com8 | ||||||||
| C36 | _local | ||||||||
| C48 | NIMM | NIMM | |||||||
| C55tv_off | com7tv_off | ||||||||
| C56tv_off | COM8tv_off |
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
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Tuesday, 16 October 2012
Peter Henderson: I think you are getting a few things mixed up.
MPEG4 is used on all RoI Saorview services, not just those in high definition. As MPEG4 provides the same picture "quality" in about half the bandwidth, this makes sense.
The 2k/8k comparison is not the same, as this is a "lower" level.
A DVB-T2 receiver will see the bitstream from DVB-T and not vice versa.
This has nothing at all to do with MPEG2/MPEG4 decoding.
There are some set-top boxes in the UK, those provided by BT Vision, which CAN decode MPEG4.
Saorview boxes, on the other hand, can decode MPEG2 and MPEG4, but can't see the DVB-T2 transmissions.
Also, most MPEG4 receivers can "decode" pictures in higher defintions, and resample them down to SD.
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Briantist: Does this mean that, theoretically, if the UK was to change from MPEG2 to MPEG4, then there would be room for more services (due to using less bandwidth)?
The Republic of Ireland has a single multiplex which carries standard definition services and RT Two HD so it is possible to mix them. Does Saorview use DVB-T or DVB-T2?
Is the advantage of DVB-T2 that it offers greater bitrate than DVB-T?
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Dave Lindsay: In theory, it is possible. However, Ofcom has a policy of NOT allowing MPEG4 on DVB-T, because there is a clear consume update path: Freeview HD.
You may recall that the "Sky Picnic" idea was rejected for this reason.
The long-term plan is to migrate all services to DVB-T2/MPEG4, even if they are not HD. This is in the "2020-25" planning area.
If 4G mobile services are going to expand, it is possible (not confirmed) that the three commercial multiplex will move to three single-frequency network using DVB-T2/MPEG4. Or even DVB-T2 with HEVC http://en.wikipedia.org/w…HEVC
I have created a graphic to help understand which boxes work on what...
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... Saorview is DVB-T not DVB-T2.
DVB-T2 not only offers better rates, but is more "robust" (less prone to interference) and works better in single-frequency networks.
See Freeview modes - a simplified explanation | ukfree.tv - 10 years of independent, free digital TV advice for full details
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Briantist: Thanks.
So Freeview HD (PSB3 mux) uses DVB-T2 with 256QAM. Is the reason that the NIMM is much more robust (and can therefore carry further with much less ERP) because it uses 16QAM?
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Wednesday, 17 October 2012
Dave Lindsay: Yes, that is correct.
DVB-T2 is also more robust than DVB-T at the same outputs as it has a more "modern" error correction system and it also uses advances such as the "rotated constellation".
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M
mrdtv12:38 PM
Briantist: The mode used by NIMM is in fact QPSK, 32k, 1/32, one of the most robust modes. See DUK's postcode checker.
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Saturday, 20 October 2012
E
elaine8:39 PM
very bad digital signal on c 5 and and utv is there a problem in the lisburn area bbc fine bt28
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K
KMJ,Derby10:05 PM
elaine: From Wednesday (24th October 2012) UTV, C5 etc will be carried on Mux D3+4 at 100kW. This is an increase in power from the present 2.3kW on Mux2. You should have much improved reception from then.
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K
KDM10:06 PM
I'm in N'ards, just on the fringe of the green area for Divis. After retuning on the 10th, I lost about 30 channels and UTV is now pretty unwatchable, interspersed with chirps inteh audio and blocky video. I had multiple cable drops from my antenna and have even removed my splitter and patched the aerial directly to the main TV.
Still not a lot of joy. Any suggestions gratefully received, please.
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