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 04/11/2024 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, 26 December 2012
J
jb385:39 PM
K.Barrett: Well, what you are experiencing is unfortunately not that abnormal in situations such as you have described, and if a signal is always worse on a clear relatively cloud free day then its an indication that the reception at a particular location is dependant on reflective elements, something which certain types of clouds can be rather good at.
All DTT receivers operate on a threshold level whereby the spec of the tuners circuitry determines the minimum level that a signal can be decoded at, and with this level being variable between different brands of equipment, and so if an auto-tune is carried out and the scanning circuitry detects any signals, then even if they are sitting at just a fraction under the threshold level for the particular receiver being used they will either be ignored or maybe placed up in the 800 ranges dependant on how sophisticated the receiver might be.
The other and misleading (for some) aspect of this system being, that if its intended to carry out a manual tune whereby its usual to see the signal strength / quality being indicated as soon as the channel number that's intended to be scanned is entered into the box, this being seen "before" search or scan is pressed, then should it be subsequently discovered that after having pressed same that nothing had been picked up then this is caused by the threshold level circuitry referred to, and is because that as soon as search (or scan) is pressed the threshold circuitry comes into play whereas it wasn't before, as prior to pressing scan etc the tuner was just acting like a "free of restrictions" signal sniffer and why using this facility is a superior way on monitoring signal levels during any alterations being made to the aerial, i.e: by the very fact of continuous indications being seen no matter how low the signal drops to.
Taking this explanation into account you will probably have sussed out why you do not always get the same results during any tuning exercises carried out, i.e: because of you experiencing variable levels of signals from Mendip whereby Chiseldon might take the lead as far as strength is concerned on some occasions.
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J
jb385:52 PM
K.Barrett: Just noticed that Dave Lindsay has also replied from another angle, and which if you discover that you are the only person thats having the problem could well apply, the problem possibly caused by either water having entered a junction box or even slight corrosion having developed on one of the connections, although I do appreciate that you have already indicated that you have checked on all of these possibilities.
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K
K.Barrett8:57 PM
Dave Lindsay / JB38: I don't think it is aerial or corrosion or even local interference especially as my wife and kids remind me that we had very similar problems through certain times in the winter of last year and I had forgotten that. Also why be perfect for 6 hrs today and then give problems from about 17:00?
I guess it could be water ingress but, with exception of connection at roof aerial, I have checked all cables and there isn't any corrosion or water ingress.
Also when connection to the loft aerial facing Chiseldon that is new cable top to bottom.
I have, as above, tried turning on and off all electrical appliances including heating appliances, mobile phones, dimmer switches etc.
Thank you for the current advice but I am now banking on checking with the neighbours unless there are more thoughts.
If I do concede poor aerial connection as a possibility and get an installer in to look at the aerial connection (I am not going onto the actual roof myself - told old for that now) I will upgrade the aerial and get all new double insulated foam down cable.
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K.Barrett: The answer to your question will come should the source of any interference be found. In general, any interference is likely to be when the noisy appliance is switched on and not all appliances are on at all times!
I don't understand your reasoning for thinking that it isn't local interference, especially as you say it happened before which makes me think that it is more likely to be and that whatever is generating it is only used at this time of year.
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J
jb389:33 PM
K.Barrett: I really think that you should consider it as priority with regards to making some checks with your neighbours, because unless its known if they are also experiencing the same type of problems as yourself there really isnt any point in you carrying out any further tests more than you have already done, which I may say is seemingly quite comprehensive.
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J
jb389:51 PM
K.Barrett: I had also meant to add, that as Chiseldon is located so close to your area of residence then I wouldnt really bother too much about what band of aerial you are using as it doesnt really matter, but though its the fact that you also experience problems with Chiseldon that is the main thing to look into, and along the lines of ensuring that the relay is not just repeating a problem inherited from Mendip.
By the way, although no transmitter engineering should be taking place over the Christmas period faults can still occur on the transmission (relay) side that may not be instantly known about, and so it should not be automatically assumed that the station has a clean bill of health, so to say.
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K
K.Barrett10:16 PM
Question: if I do consider upgrading the aerial what should I buy? The upgrade path for Mendip as the 800MHZ band is cleared isn't obvious.
Will the powers that be really force those of us in fringe areas through an upgrade path possibly involving multiple aerials, filters and diplexing or will a new aerial be designed that focuses on channels 21 - 59 and not tuned for the 800MHZ range?
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K
K.Barrett11:41 PM
If, as I expect, my neighbours are experiencing the same problems (Mendip and Chiseldon relay freezing on BBC) who do I report it to?
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Thursday, 27 December 2012
J
jb3812:01 AM
K.Barrett: These are lots of myths around about aerials used for DTT reception and if one is required to cover the channels mentioned then it has to be a wideband version, but though NOT one of the high gain varieties in your situation as high gain (or so called) aerials rely on being precisely focused on the signal source, this being something that cannot really be achieved in circumstances such as yours and so using one of these types will give a slightly inferior performance (glitch wise) over that a wider acceptance angle type coupled to a booster of around 15db or so minimum.
Taking this into account I would recommend using a log 40 in conjunction with a variable booster of around the rating referred to, as should less than satisfactory reception be evident with this combination then I can say with a level of confidence that nothing will improve the situation, and with this basically being because that the problem is outwith your control.
This is a link to the type of aerial referred to.
Online TV FM DAB Aerial sales
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K
K.Barrett12:01 AM
Further thoughts on interference.
If it is local RF interference (however caused) it only affects the following channels (frequencies):-
Chiseldon = 27 (522MHZ)
Mendip = 61 (794MHZ)
With all other Channels (frequencies) on both transmitters being rock solid it must surely be a problem between Mendip and Chiseldon transmitter.
Wouldn't local interference be too much of a coincidence to affect only two frequencies and both those to be the ones transmitting or relaying BBCA and some 270MHZ apart without affecting anything in between.
If it is local interference then I think it is time to call the experts as looking at it like this I am certain my neighbours will confirm they have the same problems.
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