Full Freeview on the Divis (Northern Ireland) transmitter
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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 11/11/2024 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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Friday, 2 November 2012
Tony : That Samsung set cannot receive Freeview HD signals which use DVB-T2 mode. If you are receiving the Irish channels from Black Mountain then this also uses DVB-T2 mode, even though the pictures are standard definition.
Alternatively, if you are receiving the channels directly from one of the Republic's transmitters, then these use DVB-T, but Saorview pictures use MPEG4 format. (Freeview standard definition pictures use the earlier MPEG2 format.)
The information about this model is here:
Support for PS50A457P1D
Page 2 of the manual says "Any functions related to Digital TV (DVB) will only work in countries or areas where DVB-T (MPEG2) digital terrestrial signals are broadcasted."
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Saturday, 3 November 2012
F
Fergus Maunsell6:34 PM
I got my I Cam HD Box today in the post to get RTE and TG4 at Belfast BT9 6TZ
After few hours trying to set the 4 digit code for the I can remote control for my Samsung TV, I got all HD and SD plus radio working.
One error is only on Irish channel TG4 is showing 3:4 screen size not 16:9 RTE 1 and 2 showing 16:9
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Sunday, 4 November 2012
P
Padraig12:59 PM
Hi I am using a tv Star box for Saorview and Freeview channels from the Davis transmitter I live in co Meath I am getting the 5 Multiplex's but CH23 is very weak while all the rest are 100% any Ideas anyone
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Padraig: C23 is used by Mount Leinster, so this may cause you difficulty.
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R
Ronan3:46 PM
Is it be possible to recieve Divis from Dun Leary South Dublin using a group A yagi with a masthead amp etc or have you heard any reception reports from this area ...
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Tuesday, 6 November 2012
D
David Irwin9:07 AM
hello I live just south of the border in Jenkinstown, I get the BBC channels on CH45 666mhz but the UTV/ITV channels are coming in on CH 39 618mhz, I cant find any transmitter on the map that brodcasts this combination, having said that, I can only get the UTV/ITV channels with the help of a masthead amp, on my normal chimney mounted aerial all I'm getting is the BBC channels, I wanted to locate the appropriate transmitter before upgrading my aerial/amp so that I had the correct type of aerial, can anyone help please?
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David Irwin: I can't find a transmitter that uses C39 for PSB2 (UTV/C4 etc) either. I checked the Digital UK Postcode Checker and the Ofcom Tech Guidance document and they both bear out what I've put below:
http://stakeholders.ofcom….pdf
In your general area there are two relays that each use the same three channels, albeit with PSB1 and PSB3 swapped:
- Kilkeel: PSB1=C45 PSB2=C42 PSB3(HD)=C39
- Rostrevor: PSB1=C39 PSB2=C42 PSB3(HD)=C45
So you are receiving from Kilkeel. Rostrevor is 23W and Kilkeel is 400W. Perhaps you should probably re-orientate your aerial to the latter.
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J
John Durrell12:55 PM
Coleraine
Hi,
Sorry for such a long post. I had originally posted this message on the Limavady transmitter site but am now pretty sure that our signal comes from Divis, but not 100% sure.
Since the N.Ireland switch over I can receive all the HD channels but in 1080i. My neighbour about 150 yards away can receive in 1080P (when channels are being broadcast in 1080P). I live in Ringsend not far from Limavady (10 miles) but I think (not sure) that my signal comes from Divis as we have a mountain in between us and Limavady. I have an i-Can HD set-top box running a Sharp Aquos, I have tried this box at my neighbours it gets 1080P there running through his Sony Bravia . My aerial was a Yagi type high gain red plastic bung. I was getting a signal strength of 65% same as my neighbour. I then tried a Philex 27887D SLx 32 Element Digital Wideband black plastic bung. This aerial made no difference except the signal strength was slightly lower at 62%. Both my neighbour and I use a SLx 8 way distribution box to feed the signal around the house. I have also tried by bypassing the distributor with no difference. My question is why can I not receive 1080P? Am I using the wrong aerial? Do I need an aerial with more elements or am I missing a trick somewhere else.
My reasoning for thinking that there are sometimes1080p transmissions (BBC HD seems to have the most) and that the i-Can box is OK for their reception is based on the tests I carried out below.
1) I tried the same i-c an HD box in London (Crystal Place Transmitter) on a Sony Bravia, it reported 1080P. The Sony set also has its own HD tuner which reports 1080P.
2) Tried the same box at neighbours in Ringsend on different Sony Bravia it also reported 1080P. This set also has its own HD tuner and it reports 1080P.
3) My Sharp Aquos plays Blurays in 1080P via HDMI.
4) However the i-Can HD box through HDMI can only sustain 1080i on this TV.
5) The i-Can has a setting to change the output and when I set it to1080P it cannot sustain the picture and sound. It will come on for a few seconds reporting 1080P and then the screen will go blank for a further few seconds. If the two Sony's are falsely reporting 1080P then that solves the issue. However if the broadcast is in 1080P then I wonder why I can't get it? Is it the aerial?
If anyone can verify that Divis is my transmitter and that indeed 1080P is being transmitted that would be very helpful. If this is the case it seems that both aerials cant sustain 1080P and therefore would a wideband aerial with more elements do the trick? Any suggestions would be much appreciated.
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John's: mapJ's Freeview map terrainJ's terrain plot wavesJ's frequency data J's Freeview Detailed Coverage
M
Mike Dimmick2:48 PM
John Durrell: The difference in what your TV reports is *probably* down to using an external receiver rather than having the HD tuner built in to the set.
This is complicated by the fact that, on Freeview HD, the encoding hardware, and therefore the transmissions, can dynamically switch between 1080i50 and 1080p25 modes for every Group of Pictures (GoP). A GoP is a sequence of 15-25 pictures that are encoded using differences between the pictures, only one whole picture being sent in the set. The encoder switches mode based on how well the content compresses in each mode - if the source material was actually captured in progressive mode, or if there isn't much motion, it should compress better in progressive mode than interlaced. If there is fast motion, it will look better in interlaced mode.
It is never anything to do with your aerial - the decision of whether to choose i or p mode for a group of pictures is taken by the encoding and multiplexing hardware in London (and the BBC's backup location somewhere in the Midlands). For BBC One Northern Ireland HD, and UTV HD, a lightly-compressed high-bitrate signal is sent to the code-and-mux centre for compression and multiplexing. The resulting multiplex is sent back to Divis, where Service Information for the other multiplexes is added. It is then transmitted from Divis and carried via line feeds to Limavady and Brougher Mountain, which also transmit it. The other, relay, transmitters receive off-air from one of those three and retransmit. (Similarly, BBC One NI and BBC Two NI in standard definition are sent to the BBC's code-and-mux centres, while UTV and UTV+1 in SD are sent to ITV/C4 facilities elsewhere in London.)
The reason code-and-mux is done in England is simply that the majority of channels on most of the multiplexes only have one version for the whole UK, mostly played out or originated in London, and it makes more sense to bring in the few differences rather than send out the greater amount of content that is the same. Also, the same content is uplinked to satellites for satellite reception, where all the content for a single transponder has to be combined into one multiplex and uplinked from a single location.
The raw, uncompressed data rate for 1080p25 is the same as for 1080i50. 1080p25 means that 1080 lines are refreshed in full 25 times per second, taking 1/25th of a second, while 1080i50 means that half of the 1080 lines are refreshed in 1/50th of a second, followed by the other half in the next 1/50th of a second. In both modes, any specific line is only refreshed 25 times per second. 1080p50 doubles that to 50 times per second. Much equipment drops the '50' from the end of the indication and just reports 1080i or 1080p.
When a GoP is encoded progressively, the receiver can still send it on to the TV in interlaced mode: it just sends the lines in a different order to how it received them. There is no loss in picture quality and no difference in the apparent motion of the picture.
It may be possible to set up your receiver to send 1080p50 to the TV, if both support it. To receive the 'HD Ready' or 'HD TV' logos, and even the 'Full HD Ready' or 'Full HD TV' logos, the TV only has to support 1080i50 input - it does not have to support 1080p50. They only have to support 1080p50 in order to receive the 'HD Ready 1080p' or 'HD TV 1080p' logos. (The word 'Full' indicates that the TV itself has 1080 display lines, without that word it might have only 720 lines.)
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Thursday, 8 November 2012
K
Keith4:30 AM
Hi i live in Blackrock, Co.Louth. I am using a wideband aerial which i mounted in the loft, but can not get any luck in keeping up signal from Divis. My mate lives only 3 miles away in dundalk and hes getting signal without any amplifiers at all.
I have tried adding 2 differnet masthead amplifiers but still no joy.
Anybody having any ideas as to what i am doing wrong?
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