Full Freeview on the Mendip (Somerset, England) transmitter
 | Google Streetview |  | Google map |  | Bing map |  | Google Earth |  | 51.237,-2.626 or 51°14'12"N 2°37'33"W |  | BA5 3LB |
The symbol shows the location of the Mendip (Somerset, England) transmitter which serves 720,000 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 Mendip (Somerset, England) mast?
Mendip transmitter - Mendip 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 Mendip 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 Mendip transmitter?
ITV West Country News (East) 0.9m homes 3.4%
from Bristol BS4 3HG, 23km north (11°)
to ITV West region - 61 masts.
All of lunch, weekend and 50% evening news is shared with West Country (West)
Are there any self-help relays?
| Cheddar | Transposer | 15 km E Weston-super-Mare | 1674 homes |
| Luccombe | Active deflector | 6 km w Minehead | 38 homes |
How will the Mendip (Somerset, England) transmission frequencies change over time?
| 1984-97 | 1997-98 | 1998-2010 | 2010-13 | 2013-18 | 2013-17 | 27 Feb 2018 | |||
| C/D E | E | E | C/D E | C/D E T | W T | W T | |||
| C30 | _local | ||||||||
| C32 | BBCA | ||||||||
| C33 | com7 | com7 | |||||||
| C34 | D3+4 | ||||||||
| C35 | com8 | com8 | |||||||
| C36 | ArqB | ||||||||
| C37 | C5waves | C5waves | |||||||
| C48 | SDN | SDN | SDN | SDN | |||||
| C49tv_off | BBCA | BBCA | |||||||
| C51tv_off | LBS | LBS | |||||||
| C52tv_off | ArqB | ArqB | ArqB | ||||||
| C54tv_off | C4waves | C4waves | C4waves | D3+4 | D3+4 | D3+4 | |||
| C55tv_off | com7tv_off | ||||||||
| C56tv_off | ArqA | ArqA | ArqA | COM8tv_off | |||||
| C58tv_off | BBC1waves | BBC1waves | BBC1waves | BBCB | BBCB | BBCB | |||
| C61 | ITVwaves | ITVwaves | ITVwaves | BBCA | |||||
| C64 | BBC2waves | BBC2waves | BBC2waves |
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 | 500kW | |
| Analogue 5 | (-6dB) 126kW | |
| SDN, ARQA, ARQB, BBCA, D3+4, BBCB | (-7dB) 100kW | |
| com7 | (-8.4dB) 72.4kW | |
| com8 | (-8.6dB) 69.1kW | |
| Mux 1*, Mux 2*, Mux A*, Mux B*, Mux C*, Mux D*, LBS | (-17dB) 10kW |
Which companies have run the Channel 3 services in the Mendip transmitter area
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Wednesday, 16 March 2011
J
Jonathan10:10 AM
Jim F: Thanks for your attenuator suggestion. Your theory sounds very plausible, as we have two signal boosters - one on the (very high) roof aerial itself and another in the loft - that were necessary before Mendip's switchover. (We live behind a hill.)
It may be that the signal would now benefit from permanent attentuation, as we are still getting traffic interference (also boosted I presume) on some PSB channels, notably C4, but I'll try it first just for retuning. I presume that a variable attentuator would be best, esp. if it may be needed permanently. Most seem to be 20db max - would it be worth spending more on a 25db max?
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J
Jim F7:36 PM
Jonathan: I'd hesitate before recommending permanent attenuation. I have a box of attenuators so I can choose the value that I need (but I also have a meter which means I'm not having guess the signal power). I know a chap that lives almost directly underneath the Clennon Valley relay Tx - his aerial points to Beacon Hill (main Tx) and his Panasonic kit (TV & DVD recorder) needs 42dB of attenuation for tuning, but works fine when that's removed and it gets the full whack. Without the attenuator, both will tune themselves to the Occombe Valley relay (next nearest), which gives pixellation 'cos the power is low & quality poor.
I'd suggest trying the aerial without any boosters - it may have helped for analogue, but digital may not need them.
24dB is the highest attenuator I use - doesn't cost any more than the 3, 6, 9 (or 10), 12 or 18dB attenuators (have a look at CPC), or you could get one of those little variable ones (don't think they go up beyond 20dB though).
Traffic interference - is your coax in good condition (i.e. hasn't got a break in the jacket & screen)?
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Thursday, 17 March 2011
J
Jonathan2:21 PM
Jim F: Thanks for the further advice. Our boosters were actually for the digital signal (analogue was fine!) before Mendip itself boosted the power - on PSBs - at switchover. Of course, the problem is that they've always boosted the traffic inteference too, which used to be far worse before switchover, so I doubt the coax has deteroriated. The entire system was checked or modified three times by different professional engineers, and there was no real improvement until Mendip's switchover, and then only on PSBs. For almost 10 years, digital TV here was only watchable during the middle of the night.
After switchover, we did try taking out the loft booster but then the signal disappeared completely on all channels. The booster on the aerial itself is almost inaccessible; the roof is so high and dangerous that even experienced engineers are reluctant to go on it!
The variable attentuators on eBay seem to go up to 25db, but these cost quite a bit more than the 0-20db ones.
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Saturday, 19 March 2011
J
Jim F8:59 PM
Jonathan: Interesting reading about your setup and performance. I think you're saying you have a masthead amp and a further amp (distribution?) in the loft.
You're 10.7km from Mendip, with the edge of a hill (Folly Hill / Clapton) slightly in the way of the signal.
Pre-switchover, I'd expect the adjacent analogue channels would've made things tricky except for MUX C and D (UHF 56 and 67) which weren't adjacent.
Post-switchover, those PSBs are up at 100kW whilst two COMs are at 10kW and your elusive Arq B is at 26kW (on UHF 67).
When you removed the loft amp, did you put in something to provide power up to the masthead amp? Without any power it wouldn't give you any signal. I'm hoping that your loft amp "is" providing power up to the masthead (and isn't full of mains ripple on top of the 12VDC).
Looking at the map, I'm still concerned that you're needing any amplification - there should be loads of signal, and no interference from traffic at all.
When you get the traffic causing trouble, does this show on the Panasonic power / quality indicators?
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Sunday, 20 March 2011
M
Mr. M. Brooks9:10 AM
with regard to channels 12 Yesterday and 15 Film 4. The signal we receve from Mendip Transmitter is low however, sometimes we get good reception and other times nothing at all or picture breakup.Our aerial is on the roof in the correct position. Since the digital change we had several months with no trouble at all but recently we get this problem. Can you suggest a reasonfor this.
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J
Jonathan11:32 AM
Jim F: Yes, there's a masthead booster and a loft booster (just for the one receiver). I can't recall exactly what happened when we tried to remove the loft booster - I didn't do it personally, but I think we tried different ways of re-connecting it, then just let it remain.
Since switchover, I've been almost happy with the stronger PSB channels, but sometimes during afternoons - and particularly when rainy - the traffic interference will occur maybe 3-4 times an hour on Channel 4 (and the weaker multiplexes). We live on an increasingly busy crossroads and the interference can usually be linked to mopeds, passing or waiting at the junction. I haven't tried monitoring the signal strength when it happens (I rarely watch live TV).
I tried the variable attenuator (at different settings) yesterday while trying to save the Arq B channels, but the Panasonic - while finding them easily - still refuses to install them, whether on the normal full signal strength or anything lower. Maybe I'll have to try a full re-tune but I worry I'll lose the other muxes too. I think I'll ask on AV Forums to see if anyone else has trouble re Mendip and Panasonic equipment on UHF 67.
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J
Jim F11:23 PM
Jonathan: I'm thinking that the retune event for Mendip on 11th January has changed both the Arq B MUX frequency and the programme content.
Prior to 11th Jan, the MUX was operating in 2k mode on UHF59 with the "pre-switchover" channel lineup (i.e. no HD programmes, and with things like BBC Four and the BBC radio programmes).
After 11th Jan, the MUX is now operating in 8k mode on UHF67, and may also have the "post-switchover" channel lineup (i.e. HD programmes only, no radio at all).
Manually tuning your Panasonic to UHF67 should show a full (green) power bar, but nothing for the quality bar (unless your recorder has an HD tuner?). There will still be a number 10 at the end, but there wouldn't be any (green) bar at all.
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J
Jim F11:34 PM
Oops - that's cobblers what I've just typed Jonathan.
I've sent a mixed MUX message - sorry; please ignore above!
The change to the MUX (2k to 8k) is right, but the programmes (Film4 etc.) are similar to what they were before.
The full retune for the Panasonic may well be the next thing to try - it could well be holding on to the old tuning information for these channels. You'd have to make sure the box had completely "forgotten" any of the old tuning info and then start from scratch.
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Wednesday, 23 March 2011
M
Mr. M. Brooks4:19 PM
Bristol
Further to my previous e-mail on the 20th March, I get a perfect picture on freeview channels 12 yesterday, and 15 film 4 in the morning up to about 9.15.from then there is a "no signal" until about 10.45 at night then the picture is perfect again. This means during daylight hours between the times above I am unable to watch these channels. Can you let me know the reason for this please
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Mr.'s: mapM's Freeview map terrainM's terrain plot wavesM's frequency data M's Freeview Detailed Coverage
M
Mike Dimmick4:38 PM
Reading
Mr M Brooks: If you had Freeview before switchover and didn't have problems, the signal is could now be too strong. If you have any amplifiers, remove them. If you don't have any amplifiers, consider adding an attenuator.
In January, the ArqB multiplex changed mode to increase capacity - but at the cost of needing a larger signal-to-noise ratio. This has made the coverage area smaller. However, the Digital UK predictor shows you should be well within coverage.
The ArqB multiplex will change channel and increase in power at the end of September. That may resolve the problem.
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Mike's: mapM's Freeview map terrainM's terrain plot wavesM's frequency data M's Freeview Detailed Coverage
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