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.
This transmitter has no current reported problems
The BBC and Digital UK report there are no faults or engineering work on the Divis (Northern Ireland) transmitter._______
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, 18 January 2013
L
Lynn Steenson12:19 AM
Dave Lindsay:
I have tried to bypass the amplifier but if I do that i get no channels at all.
Its an old one- Fringe Electronics Hi-Current P1290, its either on or off no turning up or down!
Yes we are indeed in the green area on the map above!
We are currently receiving all saorview channels and (freeview apart from the coms.)
Do you think if we were getting the coms before the DSO with current aerial/amp that maybe it could be the power strength that Divis is broadcasting the coms? It being only half the strength of the psbs?
I used the digital tv postcode checker for coverage of a BT postcode BT603DP in N.Ireland which is close to us.We are not far from the border!
It shows good reception for the psbs and variable reception for the channels we are missing!?
Thanks for all your help so far.
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Sunday, 20 January 2013
Lynn Steenson: The Digital UK predictor essentially provides a statistic on the likelihood of success. COM6 is "good" but the other two are considered "variable". I imagine that this is more down to the way in which it calculates the likelihood of interference from other transmitters that use the same channel. I wouldn't be too concerned about that.
The Fringe P1290 is a power supply for an amplifier and not an amplifier. The amplifier is probably on the roof or near to the aerial. Turning the power of to the amplifier will likely result in no signal coming out.
You appear not to have many more options left without getting into it deeper. Removing the amplifier, or turning it down (if possible), is probably the next thing that needs trying.
The lower power COMs will affect some fringe viewers - that is those who can "only just" pick up the PSBs. This would appear not to be an issue for you. You may have line-of-sight or not far off which is why I'm thinking that the amplifier isn't necessary, or at least at the current magnitude.
An attenuator on the aerial lead may reduce the signal strength sufficiently if you can't get to remove the amp or reduce its level. An attenuator reduces the signal level which is the opposite of an amplifier. Therefore an attenuator would be acting to cancel out some of the amplification of the amp.
Various ones are available. Here is one such example that is variable:
TV Aerial Attenuator Variable 0-20Db Freeview Digital | eBay
Try to reduce the signal strength (to say 75 or 80%) and see if the quality of the COMs increases and they become available to you.
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Monday, 21 January 2013
L
Lynn Steenson6:11 PM
Armagh
Dave Lindsay:
We also have a Fringe Mini 4 Distribution Unit 40 - 860 Mhz.
It has one input and 4 x 6db. outputs.
Would the amplifier be built into this?
I also tried to bypass this but no success!
I think I will get the suggested variable attenuator and take it from there.
Thank you!
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Lynn's: mapL's Freeview map terrainL's terrain plot wavesL's frequency data L's Freeview Detailed Coverage
Tuesday, 22 January 2013
Lynn Steenson: The distribution unit does have a degree of amplification (+6dB). Cables, for example, have a degree of loss (i.e. minus so many dB, depending on type and length). The objective of an attenuator is to reduce the signal further.
Is this fed directly from the aerial or via a Sky box?
I've had another thought: I wonder if your receiver might not be built to receive the COM channels.
The COM channels use a different mode to the PSBs, and different to that which their equivalent multiplexes used before switchover.
The UK's standard definition networks and Ireland's Saorview network both use the DVB-T system (it standing for "Digital Video Broadcasting - Terrestrial").
However, there are a number of modes, which are sub-standards or parts of the DVB-T standard. The UK PSBs and UK COMs operate using a different mode.
If the receiver you are using is not Freeview approved then I wonder if it could be the case that it isn't designed to operate in the mode used for the COMs. The result could perhaps be that signal strength is registered but no quality, as is what you are getting.
I'm not a professional so am simply wondering whether such devices might exist. I know that some really old digital receivers were rendered useless at switchover because they weren't designed to comply with the DVB-T standard in full.
What's the make and model of the receiver you are using? It might be possible to find the specifications and work out whether this might be the cause.
Presumably you having a distribution amp means that you have more than one receiver. What do the others do?
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Wednesday, 23 January 2013
L
Lynn Steenson8:27 PM
Dave Lindsay: This distribution unit is fed directly from the 48 Element High Gain Digital TV Aerial.
The receiver is built into the tv Samsung LE40D503F7W.It picks up the saorview channels fine.
I also have an Echostar HDT610RGB which picks up the HD channels and saorview as well.
All other tvs just have cheap Freeview boxes eg Alba/Bush but im mainly concerned with the main tv and echostar.
I can see i have the option of DVB-T and DVB-T2 in the echostar box but once i choose DVB-T2 on channel 23 the signal strength 0 and quality 0.
with DVB-T on channel 23 for example I have 58 signal level and 0 quality.
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Thursday, 24 January 2013
J
jb388:14 AM
Lynn Steenson: On reading back through your various postings on the issue of zero quality being indicated on all of the COM channels, it would be interesting to know the outcome if you first of all blanked out all channels already stored in the TV's memory by carrying out an auto-tune with the aerial connection removed, checking the EPG list on completion of the scan to ensure that nothing is being indicated, then follow this by going into the TV's manual tune facility and entering Ch23 and check if the quality is still zero, if though it isn't then carry out a scan on this channel then when completed select ITV3 and check if a picture is showing.
By the way regarding your Echostar, if you scan channel 23 whilst its set on DVB-T2 than that will result in a zero indication, as the tuner will not recognise the signal.
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Saturday, 26 January 2013
L
Lynn Steenson7:59 PM
Dave Lindsay: I got the suggested attenuator but not having any success.
It reduces the signal strength only. for example on ITV3 (within the guide), original signal strength is 96 and quality is 0.
When I use the attenuator and I reduce signal to say 75 the quality remains at 0.
The attenuator seems to have no effect on the signal quality at all.
There is a very distorted jumpy picture on ITV3 when signal strength is at 96!
Do I maybe need a bigger amplifier?
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L
Lynn Steenson8:08 PM
Jb38: I did a retune with the aerial disconnected.Then the list of channels is empty. Then after connect aerial ch23 quality is still zero. As you can see above I tried an attenuator but to no avail. Any other ideas?
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Sunday, 27 January 2013
J
jb388:47 AM
Lynn Steenson: Thanks for the update on that test, but on once again reading over your various replies made I cant actually see you having mentioned that you receive the COM channels on anything at all, and so the question is do you? because if you don't then the issue of your main TV does not really come into the equation as the problem is purely one concerning signal levels.
The other point is that the substitute post code that you provided indicates as being roughly 41 miles away from Divis and at that distance its unlikely that anyone could suffer from an excessive signal level, this backed up by the fact of you being able to receive the PSB's OK and yet they transmit with twice the ERP of the COM's, and so dependant on your answer to my initial question insomuch whether or not you can receive the COM's on any of your devices, if the answer is no then I have a suspicion that you might well be suffering from an effect that sometimes happens with viewers at distances when a transmitter increases power insomuch that the signal received can actually drop.
Although this type of thing can be caused by the way the signal is radiated by the transmitter mast, it can also be an indication that the signal that was previously received had relied on a strong element of reflection from something such as a hill or a tall building, but that the increased signal power has changed the angle of reflection whereby someone further away than you might now be receiving a superior level of signal at your expense.
The problem is, that if the strength appears as being high but with no quality being indicated then amplification will not help the situation one iota, the only thing that's liable to have any effect (but not guaranteed to do so) is experimenting with aerial positions, and in cases where this type of situation applies high gain aerials make the situation worse as these work on the principle of focusing on the signal source.
Anyway, the latter comments will obviously not be applicable in your case "if" you can receive the Com's on your other boxes.
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L
Lynn Steenson12:06 PM
jb38: No we can not get the COMs on any other boxes.
Only wen i add the channel manually will it appear in the tv list (using main tv or echostar) then once i check the signal within the guide its level varies but quality always 0 e.g. ITV3
Before the DSO we got ALL channels at the same set up/position of aerial.
Yes we are about 42miles from Divis and are within the green area on the map above.
So you reckon we need to maybe move the aerial slightly? even though before DSO we got all channels fine?
Thanks for your help!
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