Freeview Light on the Backwell (North Somerset, England) transmitter
 | Google map |  | Bing map |  | Google Earth |  | 51.441,-2.724 or 51°26'28"N 2°43'25"W |  | BS48 1NY |
The symbol shows the location of the Backwell (North Somerset, England) transmitter which serves 4,600 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 Backwell (North Somerset, England) transmitter._______
Digital television services are broadcast on a multiplexes (or Mux) where many stations occupy a single broadcast frequency, as shown below.
H/V: aerial position (horizontal or vertical)
The Backwell (North Somerset, England) mast is a public service broadcasting (PSB) transmitter, it does not provide these commercial (COM) channels: U&Yesterday, 4seven, 5Action, 5STAR, 5USA, Al Jazeera Eng, Al Jazeera English, Blaze, Blaze +1, Challenge, Channel 5 +1, DMAX, E4 Extra, YAAAS!, Film4 +1, Food Network, FRANCE 24 (in English), GREAT! action, GREAT! christmas, GREAT! movies, GREAT! romance mix, HGTV, HobbyMaker, ITV2 +1, ITV3 +1, ITV4 +1, ITVBe +1, Legend, PBS America, Quest +1, Quest Red, Really, Sky Mix, Sky News, Talking Pictures TV, That's 90s, That's TV 2, Together TV, TRUE CRIME, TRUE CRIME XTRA, U&Dave, U&Dave ja vu, U&Drama +1, U&W.
If you want to watch these channels, your aerial must point to one of the 80 Full service Freeview transmitters. For more information see the will there ever be more services on the Freeview Light transmitters? page.
Which Freeview channels does the Backwell 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.
| Mux | H/V | Frequency | Height | Mode | Watts |
| PSB1 BBCA | V max | C25 (506.0MHz) | 125m | DTG- | 19W |
 1 BBC One (SD) West, 2 BBC Two England, 9 BBC Four, 23 BBC Three, 201 CBBC, 202 CBeebies, 231 BBC News, 232 BBC Parliament, plus 17 others | |||||
| PSB2 D3+4 | V max | C28 (530.0MHz) | 125m | DTG- | 19W |
 3 ITV 1 (SD) (West), 4 Channel 4 (SD) South ads, 5 Channel 5, 6 ITV 2, 10 ITV3, 13 E4, 14 Film4, 15 Channel 4 +1 South ads, 18 More4, 26 ITV4, 28 ITVBe, 30 E4 +1, 35 ITV1 +1 (West), 71 That’s 60s, | |||||
| PSB3 BBCB | V max | C22 (482.0MHz) | 125m | DTG- | 19W |
 46 5SELECT, 101 BBC One HD West, 102 BBC Two HD England, 103 ITV 1 HD (ITV Meridian Southampton), 104 Channel 4 HD South ads, 105 Channel 5 HD, 106 BBC Four HD, 107 BBC Three HD, 204 CBBC HD, 205 CBeebies HD, plus 1 others | |||||
Are you trying to watch these 44 Freeview channels?
The Backwell (North Somerset, England) mast is a public service broadcasting (PSB) transmitter, it does not provide these commercial (COM) channels: U&Yesterday, 4seven, 5Action, 5STAR, 5USA, Al Jazeera Eng, Al Jazeera English, Blaze, Blaze +1, Challenge, Channel 5 +1, DMAX, E4 Extra, YAAAS!, Film4 +1, Food Network, FRANCE 24 (in English), GREAT! action, GREAT! christmas, GREAT! movies, GREAT! romance mix, HGTV, HobbyMaker, ITV2 +1, ITV3 +1, ITV4 +1, ITVBe +1, Legend, PBS America, Quest +1, Quest Red, Really, Sky Mix, Sky News, Talking Pictures TV, That's 90s, That's TV 2, Together TV, TRUE CRIME, TRUE CRIME XTRA, U&Dave, U&Dave ja vu, U&Drama +1, U&W.
If you want to watch these channels, your aerial must point to one of the 80 Full service Freeview transmitters. For more information see the will there ever be more services on the Freeview Light transmitters? page.
Which BBC and ITV regional news can I watch from the Backwell transmitter?
BBC Points West 0.9m homes 3.4%
from Bristol BS8 2LR, 8km east-northeast (75°)
to BBC West region - 60 masts.
ITV West Country News (East) 0.9m homes 3.4%
from Bristol BS4 3HG, 11km east (90°)
to ITV West region - 61 masts.
All of lunch, weekend and 50% evening news is shared with West Country (West)
How will the Backwell (North Somerset, England) transmission frequencies change over time?
| 1984-97 | 1997-98 | 1998-2010 | 2010-13 | 5 Jun 2019 | |||||
| A K T | A K T | A K T | A K T | A K T | |||||
| C22 | BBC1waves | BBC1waves | BBC1waves | BBCB | BBCB | ||||
| C25 | ITVwaves | ITVwaves | ITVwaves | BBCA | BBCA | ||||
| C28 | BBC2waves | BBC2waves | BBC2waves | D3+4 | D3+4 | ||||
| C32 | C4waves | C4waves | C4waves |
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 24 Mar 10 and 7 Apr 10.
How do the old analogue and currrent digital signal levels compare?
| Analogue 1-4 | 94W | |
| BBCA, D3+4, BBCB | (-6.9dB) 19W |
Which companies have run the Channel 3 services in the Mendip transmitter area
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Saturday, 13 April 2024
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Paul Dursley6:17 PM
Steve Donaldson:
Evening
Inline filter received and fitted - made absolutely no difference to C22 signal strength or quality; C25 and C28 unaffected.
Still, the original issue is 'resolved' in so much that I am receiving the BCC West HD and other C22 TV channels.
Not sure where that leaves the us with the discrepancy of signal strength and quality for C22 vs. C25 and C28 from the Backwell transmitter.
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Steve Donaldson7:31 PM
Paul Dursley: Considering what I have found, which follows below, I'm not surprised the filter has had no effect. I believe this is an issue with reception of Mendip by the Backwell transmitter and needs reporting to the BBC.
The signal path between the Backwell transmitter and Mendip runs close to the ground for around a mile where it goes over the top of Barrow Hill. The signal path is the line through free space between the transmitting aerial of Mendip and the receiving aerial of Backwell. I think this is why there are two receive aerials on the Backwell transmitter.
I suspect the reason you lost reception of PSB3 (C22) and at the same time had lower quality on PSB2 (C28) is because Mendip was broadcasting from its reserve antenna. This is lower down the mast than the main which is at the top. I think that PSB3 came back because Mendip returned to transmitting from its main antenna.
The three Mendip channels for the PSBs are C32 (PSB1), C34 (PSB2) and C35 (PSB3). If your issue is in fact a reception issue for the Backwell transmitter then when you lost PSB3 it was C35 that was worst impacted with C34 less so (you had lower quality on PSB2). If this was because Mendip was on its reserve antenna and now it is on its main, then the quality issue on C22 may in fact be a quality issue on C35 as received by the Backwell transmitter.
Thus, it looks like the objects in the signal path between Mendip and Backwell are acting to the detriment of reception in the frequency range of C35 (around 586MHz). With the lower height of the reserve antenna the obstruction in the path increased, and when this happened the impact on reception on C35 frequencies became more pronounced, spilling over into the adjacent channel, C34.
- Terrain Plots -
I have set out the aerial heights below. Here is a terrain plot with Backwell on the left and Mendip on the right:
Terrain between ( m a.g.l.) and (antenna m a.g.l.) - Optimising UK DTT Freeview and Radio aerial location
The plotter uses six-figure OS grid references, meaning the locations of the two transmitters are set to the 100m interval closest to where they are. Backwell is set a few tens of metres away from its true location where the ground height is a little higher, so I have compensated by reducing the height of the antenna. For the height of the Mendip antenna I have entered that of the lower/bottom of the reserve, so we can see worst-case scenario, with Mendip transmitting from its lowest antenna.
The yellow line denotes the line-of-sight and the pink line is the outer of the first Fresnel zone. The Fresnel zone is the area between the pink line and yellow line. Anything in this area can have the potential to affect reception. This isn't to say that it will, but we can see that the ground and objects on it are in the Fresnel zone for around a mile, from somewhere about 2.6 miles out to maybe 3.7 miles out from Backwell. This corresponds roughly to a line over Barrow Hill from about The Conygar (around Water Catch Farm) through to the high ground of Yewtree Farm, which is to the south of Freemans Quarry and north of the A38.
The point then is that the lowering in height of the Mendip antenna (by way of switching from main to reserve) increases the level of obstruction in general present in the Fresnel zone (the Fresnel zone having lowered also). Increasing its height by returning to the main reduces the obstruction.
This is a plot from the Backwell receive to the bottom of the Mendip main antenna:
Terrain between ( m a.g.l.) and (antenna m a.g.l.) - Optimising UK DTT Freeview and Radio aerial location
- Aerial Heights -
Ofcom publishes the average aerial heights of transmitting antennas (main, not reserve). I referred to planning application diagrams for the height of the Backwell receive, and Mendip main and reserve antennas height spans (source reference notes in square brackets):
-- Backwell --
Site height: 96m
Receive aerial height above ground: 23m [1]
-- Mendip --
Site height: 303m
Main antenna height: from 282.3m to 293.7m [2]
Reserve antenna height: from 245.7m to 257.2m [2]
~~
The Mendip source [2] was published in 2013 and therefore with the previous Mendip antennas, as they were subsequently replaced for 700MHz Clearance. However, the current ones are in the same place, so the figures will be still relevant.
As can be seen in photos[3], between the main TV and reserve TV aerials are DAB and FM broadcast antennas. I checked the height of these other antennas and they are between the main TV and reserve TV heights quoted above, so those figures look to be right. The average height of the main TV is given as 288m, which ties in with the above.
We can see from this that the Mendip reserve antenna is 36.6m lower, from the bottom of the main to the bottom of the reserve.
_____
[1] Planning application 15/P/1969/F with North Somerset council, 'Proposed Elevation' document.
[2] Planning application 2013/1080 with Somerset Council, East District (former Mendip District), 'Existing SE Elevation' document.
[3] mb21 - The Transmission Gallery
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Chris.SE11:15 PM
Steve Donaldson:
Whilst I'm not going to dispute your terrain analysis and hypothesis which is always very thorough and very likely to be the cause of the problems, there is one statement that I will disagree with -
Quote "Considering what I have found, which follows below, I'm not surprised the filter has had no effect"
It is ONLY because the filter has had NO effect that it PROVES the problem is not related to Mobile Cell Interference and therefore supports the hypothesis you've presented.
Paul Dursley:
In a previous post you mentioned C22 signal Quality varying in certain weather conditions but implied that at best is was only 7/10. Would that be correct? And what sort of figure do you get for C28 in such conditions, I've got the impression that it's 10/10 for the most part.
This could also be relevant information when making a report to the BBC.
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Sunday, 14 April 2024
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Paul Dursley9:45 AM
Steve Donaldson:
Hi Steve,
Thank you for your very thorough analysis of the signal transmission and reception between the Mendip and Backwell antenna. The analysis does fit my reported TV reception (or not, initially) symptoms over the past week or so from the Backwell transmitter and in conjunction with engineering works at Mendip.
The ineffective influence of the filter only bolsters the conclusion of your analysis.
You mention reporting the issue of reception by Backwell of the Mendip signal to the BBC - who would be responsible for making that report?
If it's me as a 'customer' of the BBC I will quite happily report this as an issue. Presumably there is no problem with referencing our discourse over the past week or so?
Once again thank you for assisstance with my reception problem.
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Paul Dursley9:52 AM
Chris.SE:
Hi Steve,
Thank you for your assistance over the past week or so regarding my recent TV reception problems. The ineffective nature of the filter certainly supports the the conclusion of signal transmission and reception between Mendip and Backwell antenna.
I guess its an issue I'll have to live with unless the BBC can be persuaded to address it - not going to hold my breath....
Thanks again
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Chris.SE3:39 PM
Paul Dursley:
What I'm not certain of, is how effectively the BBC monitor Relay transmitters such as Backwell. Whilst it looks as though it's an off-air feed from Mendip, that could be just a backup now and it could be line fed or microwave link fed, many Relay transmitters have had links updated in recent times, but that doesn't seem to fit with what has been experienced.
The usual source of such information is sites like mb21 where the question has been asked by someone in the past and the information added to the site.
Out of curiosity, have you asked any neighbours if they found a similar/same problem?
Did you manage to have a look at the condition of your coax?
It's worth remembering that there's always the possibility of degradation of your aerial installation - detail not yet discovered, especially as you mentioned variations with weather (which of course could still be a transmitter issue).
If you aerial is a standard Yagi type, such as similar in appearance to -
https://www.blake-uk.com/aerials-tv-yagi/10-element-contract-pcb-balun-group-k-channels-2148.html maybe with a bigger grid and/or longer OR
https://www.blake-uk.com/aerials-tv-yagi/13-ele9-dir-dig-contract-grp-t-f-type-std-s-caiab162-channels-2160.html
then the gain of these aerials drops with the lower channel numbers, so you'd get less signal, and if it was marginal for some reason (a fault on the installation - eg. ingress of rain, later drying out) this might explain the issue.
If at some future date, you find an issue or decide to replace your aerial installation, then I'd consider something like a Group K Log periodic which will have a flat response across the channels Such as -
https://www.blake-uk.com/aerials-tv-log/28-element-log-periodic-group-k-aerial.html
or if higher gain is needed -
https://www.blake-uk.com/aerials-tv-log/56-element-log-periodic-group-k-aerial-new-double-element-design.html
There are some other manufacturers of Group K Log periodic.
What you certainly don't want is a replacement that is a wideband aerial of any type as this leaves you more vulnerable to possible mobile cell interference, should there be more new/upgraded masts in the future (quite possible). Group K is UHF C21-C48. No TV transmitter in the UK uses any channels above C48 which is now for mobile use.
A decent aerial installer should be able to provided such an aerial and install with quality double screened coax.
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Monday, 15 April 2024
P
Paul Dursley6:47 PM
Chris.SE:
Hi Chris thanks for your latest response.
I have a pretty standard Yagi style aerial - nothing special.
I've checked as much of the coaxial cable as I can get to including in the loft and it all seems pretty good - no obvious signs of distress or damp on it. Of course I haven't been able to get onto the roof and check at the aerial itself so that remains an unknown in terms of condition.
I think I'm the only one around here locally who has Luddite tendencies and is still using Freeview terrestrial TV. Did check with the local TV shop/installer who said that he had had nobody complaining of a lost terrestrial signal but that probably means not may people are relying solely on terrestrial TV.
I may just consider a new aerial installation and use manual tuning only to get the Backwell signals. However this will mean the loss of some channels I watch quite a bit but come in from Wenvoe.
Presumably there isn't an issue realigning/polarising the existing aerial to Wenvoe and adding a new Group K Log periodic for Backwell and splicing the cables before the wall plate.
It's either that or I may bite the bullet and plump for a Freesat installation!
Any thoughts?
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Tuesday, 16 April 2024
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Chris.SE2:50 PM
Paul Dursley:
Hi Paul. I'm surprised none of your neighbours watch the Freeview HD channels (if they have aerials pointing at Backwell, and you can't be that much of a luddite if you have an HD TV :)
You could certainly contemplate two aerials BUT you cannot just "splice" the two cables together, they need to be combined properly - these days usually by using a splitter in reverse AND it would need to be a low insertion loss splitter (I'll comment more later). Whilst I don't think I'd be concerned about the Wenvoe signal, you Backwell one may not be quite strong enough, so either a bit of experimentation is needed or some professional checking with a proper professional signal strength meter.
You might not need an aerial pointing at Wenvoe if the signal received of the side of the Backwell aerial is strong enough, as you no doubt have done, you can manually tune the Wenvoe channels you want.
Something else I've not asked, is the TV the only thing connected to the wallplate or does the signal route via a PVR/VHS recorder or similar?
If yes, and the latter, does it have an RF output and what channel is it set to (even if you don't use the RF)?
If you have any HDMI cables, keep them as far away as possible from aerial cables as they have been known to cause interference.
If the signal does route via other equipment, check the signal strength and quality of the multiplexes and then plug the aerial direct to the TV and repeat the measurements.
How many elements (rods & dipole and grid(?) does your aerial have?
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Wednesday, 17 April 2024
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Paul Dursley5:41 PM
Chris.SE:
Hi Chris - the neighbours I talk with went to satellite pretty quickly on moving here (a new build estate) given the poor Freeview TV selection from Backwell. Most recently satellite is being dropped in favour of internet TV now that we have a decent fibre optic connection. Seems its more reliable than than satellite apparently.
There are no other components between the aerial and the TV so nothing getting in the way there.
The aerial itself is 12 element, rounded dipole (not plate type) and single plate type reflector vertically polarised.
The Backwell signal strength vs insertion loss with a splitter might well be a problem. I think the splitters are cheap enough so I could insert one inline between the wall plate and the TV then check signal strength on the TV set up page(s).
As for having an HD TV, it was all I could get - they were sold out of the Black & White analogue ones!
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Thursday, 18 April 2024
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Chris.SE1:53 PM
Paul Dursley:
This is the sort of splitter you need, not the cheap ones with a plastic body -
https://www.screwfix.com/…4534
if you have a Screwfix within easy reach, Or for example -
eBay item number:37223707416 OR eBay item number:276418817108
BUT unless you've got another device to connect to the 2nd port you may have a mismatch which could introduce misleading figures.
You'd be better experimenting with an attenuator. And having had a look around I see there are some real rip-off prices being charged for say a 3dB coax attenuator, so unless your local TV/aerial shop has one real cheap, I'd suggest you get one of these, plenty of scope for experimenting -
Close
OR eBay item number:330646460117
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