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Full Freeview on the Divis (Northern Ireland) transmitter

first published this on - UK Free TV
sa_streetviewGoogle Streetviewsa_gmapsGoogle mapsa_bingBing mapsa_gearthGoogle Earthsa_gps54.607,-6.009 or 54°36'24"N 6°0'34"Wsa_postcodeBT17 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 15/04/2024 Screen may go black on some or all channels Digital tick


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

MuxH/VFrequencyHeightModeWatts
PSB1
BBCA
 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

PSB2
D3+4
 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),

PSB3
BBCB
 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

COM4
SDN
 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 ITVBe +1, 59 ITV3 +1, 64 Blaze, 67 TRUE CRIME, 68 TRUE CRIME XTRA, 78 TCC, 81 Blaze +1, 83 Together TV, 89 ITV4 +1, 91 WildEarth, 209 Ketchup TV, 210 Ketchup Too, 211 YAAAS!, 267 Al Jazeera English, plus 30 others

COM5
ArqA
 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

COM6
ArqB
 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), 61 GREAT! movies extra, 63 GREAT! romance mix, 71 That’s 60s, 73 HobbyMaker, 82 Talking Pictures TV, 84 PBS America, 235 Al Jazeera Eng, plus 18 others

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

NIMM
 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
VHFA K TA K TA K TK TW T
C1BBCtvwaves
C21C4wavesC4wavesC4waves+D3+4D3+4
C23SDNSDN
C24ITVwavesITVwavesITVwavesBBCBBBCB
C26ArqAArqA
C27BBC2wavesBBC2wavesBBC2wavesBBCABBCA
C29ArqB
C30LBT
C31BBC1wavesBBC1wavesBBC1waves
C33com7
C34com8
C36_local
C48NIMMNIMM
C55tv_offcom7tv_off
C56tv_offCOM8tv_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

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.

Comments
Tuesday, 16 October 2012
Briantist
sentiment_very_satisfiedOwner

10:56 AM

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's 38,915 posts GB flag
Dave Lindsay
sentiment_very_satisfiedPlatinum

11:43 AM

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's 5,724 posts GB flag
Briantist
sentiment_very_satisfiedOwner

12:49 PM

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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Briantist's 38,915 posts GB flag
Briantist
sentiment_very_satisfiedOwner

12:59 PM

... 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's 38,915 posts GB flag
Dave Lindsay
sentiment_very_satisfiedPlatinum

10:10 PM

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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Dave Lindsay's 5,724 posts GB flag
Wednesday, 17 October 2012
Briantist
sentiment_very_satisfiedOwner

8:36 AM

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".

link to this comment
Briantist's 38,915 posts GB flag
M
mrdtv
sentiment_satisfiedGold

12:38 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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mrdtv's 321 posts GB flag
Saturday, 20 October 2012
E
elaine
8:39 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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elaine's 1 post GB flag
K
KMJ,Derby
sentiment_satisfiedGold

10:05 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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KMJ,Derby's 1,811 posts GB flag
K
KDM
10:06 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.

link to this comment
KDM's 2 posts GB flag
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