Full Freeview on the Divis (Northern Ireland) transmitter
Brian Butterworth first published this on - UK Free TV
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.
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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, 6 September 2019
C
CP12:32 PM
In keeping with some other comments I have noticed a marked drop in the reception quality of com7 and com8 since 4th Sept, to the extent that the channels no longer appear on most of my receivers. Did their transmission power change when their channels moved to 51 / 60?
As far as I am aware I have a wideband aerial (black plug on the end of it), so I'm not sure why I seem to be getting such poor reception now.
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Saturday, 7 September 2019
C
Chris.SE6:48 AM
CP:
As per my previous post they are on lower power than the other muxes - 12.4 & 12.66kW respectively compared to 100kW for the PSB muxes & 50kW for the other COM muxes. They are due to reduce to 8.913kW sometime in Q1 2020 according to DigitalUK. Being SFNs (Single Frequency Networks) will no doubt contribute to lower coverage.
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Sunday, 8 September 2019
P
PeterH9:24 PM
I noticed BBC News HD reappeared on 107 on my Humax, with signal strength over 70 % but signal quality at <10% and no picture.
The guy who installed the aerials is coming on Tuesday to see what he can do, and will try the Divis aerial on it's own.
What a mess, and I payed a fair bit of money for this. I didn't mind, because everything was working perfectly on Tuesday, and the break up on Com 7 and Com 8 had gone.
We'll see what transpires on Tuesday. Hopefully, he'll sort things out.
The RT aerial would have had to be changed anyway, so it wasn't money entirely wasted, but I'm very disappointed.
Digital U.K. postcode reception predictions are not fit for purpose.
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Monday, 9 September 2019
A
ALAN HYNDMAN2:14 PM
StevensOnln1: Since last week, like a number of people, I have lost my progs on Com 7 from Divis.
I have 2 BT boxes and while all the other Muxes are at least 95% signal strength 100 % quality, my Com 7 on both boxes jumps between zero (most of the time) and 45% signal strength. I have just retuned my 2nd BT box (again) using the above Freesat reset procedure and the multiplex is not showing at all now!
I understand the reason for the change but the publicity for it was non existant and what happens now with the loss of several channels??
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PeterH: I would suspect it's 4g interfering now because of their position. Now hearing reports of people losing RTE 52 and 56 for some reason. Absolutely no information coming from there at all. My job is becoming guesswork with this mess.
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Tuesday, 10 September 2019
I
Ian.JH12:28 PM
Thanks CARL READE and Chris.SE for your replies.
A quick re-cap for the benefit of anyone else with the same problem:
I'm in Bangor, and receive Freeview via a BT YouView+ Box model: DTR-T2110
Prior to the re-tune on the 4th Sept. I was receiving all available channels via a standard looking, approx. 35 year old, chimney mounted aerial.
After the 4th Sept. re-tune I found I was missing all the channels on four multiplexes:
Com 7
Com 8
LBT
Local
After reading comments here about lower broadcast power on com7,com8 and a need for a wideband aerial, I purchased a new wideband, hi-gain aerial at the weekend (Tristar 278844tr). I mounted the aerial in the loft as I didn't have easy access to the chimney.
After a re-tune of the YouView box, all channels have now been restored.
The signal strength and signal quality of each multiplex, as measured by the YouView box is:
Com 7 Sig.Strengh. 90% Sig.Qual. 100%
Com 8 Sig.Strengh. 80% Sig.Qual. 95%
LBT Sig.Strengh. 88%. Sig.Qual. 20%
Local Sig.Strengh. 88% Sig.Qual. 20%
All other multiplexes are Sig.Strengh. 100% Sig.Qual. 100%
Please note, that even though the signal quality of LBT and Local is only 20%, the picture quality is perfect.
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C
CP7:08 PM
Thanks Chris.SE.
I know that Com7/8 have a considerably lower power output than the other mixes, but I was specifically wondering if their power output reduced from some higher level on 4th Sept? That would explain my (and many other's) sudden loss of signal. If they've been at their current power level for some time then the reason must related to the frequency / channel shift instead.
As an aside, is there any official way to complain or raise a query about this? Who would this be directed to?
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I
Ian.JH8:24 PM
CP - My first port of call when my 4th Sept. re-tune had gone awry was the official Freeview website:
Important changes to Freeview | Freeview
There is a freephone number 0808 100 0288 to deal with re-tune issues.
To my surprise, after explaining my problem re. loss of specific multiplexes, they arranged for an engineer to come out, free of charge.
When I sorted out the problem for myself, I called back to cancel the engineer visit.
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Friday, 13 September 2019
I
IA2:48 PM
I notice on the Freeview mux listing for Divis:
BBC1 NI and BBC2 NI SD are missing from BBCA.
BBC1 NI and BBC2 NI HD are missing from BBCB.
Thanks !
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Saturday, 14 September 2019
C
Chris.SE9:24 AM
IA:
I'm afraid the listings here may be/are not up-to-date see Channel listings | Freeview
CP:
I can confirm that according to DigitalUK, there was no power reduction for the COMs 7&8 muxes when the retune event took place. As far as complaining goes, OFCOM & Arqiva but, I would point out that the COMs 7&8 multiplexes are only temporary and are due to close between 2020 & 2022 as 5G take up happens. See What is 700MHz clearance? | Freeview for more information.
It would seem that as the COMs 7&8 muxes are SFNs (single frequency networks) sharing the same UHF channels around the country, it means that there will be some interference from time to time.. Experience to date seems to be single strength appears lower and signal quality can be variable during times of increased propagation (night time occasionally and dependant on weather conditions at others).
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