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Full Freeview on the Mendip (Somerset, England) transmitter

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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 25/03/2024 Pixelation or flickering on some or all channels Digital tick


Choose from three options: ■ List by multiplex ■ List by channel number ■ List by channel name
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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.

MuxH/VFrequencyHeightModeWatts
PSB1
BBCA
 H max
C32 (562.0MHz)591mDTG-100,000W
Channel icons
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
 H max
C34 (578.0MHz)591mDTG-100,000W
Channel icons
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),

PSB3
BBCB
 H max
C35 (586.0MHz)591mDTG-100,000W
Channel icons
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

COM4
SDN
 H max
C48 (690.0MHz)591mDTG-8100,000W
Channel icons
20 Drama, 21 5USA, 29 ITV2 +1, 32 5STAR, 33 5Action, 38 Channel 5 +1, 41 Legend, 42 GREAT! action, 57 Dave ja vu, 58 ITVBe +1, 59 ITV3 +1, 64 Blaze, 67 TRUE CRIME, 68 TRUE CRIME XTRA, 78 TCC, 81 Blaze +1, 83 Together TV, 89 ITV4 +1, 91 WildEarth, 209 Ketchup TV, 210 Ketchup Too, 211 YAAAS!, 267 Al Jazeera English, plus 30 others

COM5
ArqA
 H max
C33 (570.0MHz)591mDTG-8100,000W
Channel icons
11 Sky Mix, 17 Really, 19 Dave, 31 E4 Extra, 36 Sky Arts, 40 Quest Red, 43 Food Network, 47 Film4 +1, 48 Challenge, 49 4seven, 60 Drama +1, 65 That's TV 2, 70 Quest +1, 74 Yesterday +1, 75 That's 90s, 233 Sky News, plus 11 others

COM6
ArqB
 H max
C36 (594.0MHz)591mDTG-8100,000W
Channel icons
12 Quest, 25 W, 27 Yesterday, 34 GREAT! movies, 39 DMAX, 44 HGTV, 52 GREAT! romance, 56 That's TV (UK), 61 GREAT! movies extra, 63 GREAT! romance mix, 71 That’s 60s, 73 HobbyMaker, 82 Talking Pictures TV, 84 PBS America, 235 Al Jazeera Eng, plus 18 others

LBS
 H -10dB
C30 (546.0MHz)591mDTG-1210,000W
Channel icons
from 22nd September 2014: 7 Made in Bristol,

DTG-8 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?

regional news image
BBC Points West 0.9m homes 3.4%
from Bristol BS8 2LR, 25km north (3°)
to BBC West region - 60 masts.
regional news image
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?

CheddarTransposer15 km E Weston-super-Mare1674 homes
LuccombeActive deflector6 km w Minehead38 homes

How will the Mendip (Somerset, England) transmission frequencies change over time?

1984-971997-981998-20102010-132013-182013-1727 Feb 2018
C/D EEEC/D EC/D E TW TW T
C30_local
C32BBCA
C33com7com7
C34D3+4
C35com8com8
C36ArqB
C37C5wavesC5waves
C48SDNSDNSDNSDN
C49tv_off BBCABBCA
C51tv_offLBSLBS
C52tv_offArqBArqBArqB
C54tv_offC4wavesC4wavesC4wavesD3+4D3+4D3+4
C55tv_offcom7tv_off
C56tv_offArqAArqAArqACOM8tv_off
C58tv_offBBC1wavesBBC1wavesBBC1wavesBBCBBBCBBBCB
C61ITVwavesITVwavesITVwavesBBCA
C64BBC2wavesBBC2wavesBBC2waves

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

Jan 1958-Jul 1968Television Wales and the West
Jul 1968-Feb 2004Harlech Television
Feb 2004-Dec 2014ITV plc
Feb 1983-Dec 1992TV-am•
Jan 1993-Sep 2010GMTV•
Sep 2010-Dec 2014ITV Daybreak•
• Breakfast ◊ Weekends ♦ Friday night and weekends † Weekdays only. Mendip was not an original Channel 3 VHF 405-line mast: the historical information shown is the details of the company responsible for the transmitter when it began transmitting Channel 3.

Comments
Monday, 28 November 2016
S
Stephen
10:01 AM
Bristol

Over the weekend 26,27 Nov 2016 we have had none of the channels on com7 (eg BBC4 HD, BBC news HD). Checking the signal strength it is given as 0% - absolutely nothing. In the past values below 25% in heavy rain have given occasional blocky pictures. All other channels are fine with signal strengths in the 30-50% range so the roof aerial is still working OK. The web site says that there are no transmitter problems. Re-tuning in case com7 has moved frequency finds nothing. Our postcode is BS6 7JR.

Any ideas?

link to this comment
Stephen's 4 posts GB flag
Stephen's: mapS's Freeview map terrainS's terrain plot wavesS's frequency data S's Freeview Detailed Coverage
M
MikeB
sentiment_very_satisfiedPlatinum

1:45 PM

Stephen: If all the other channels are working in the 30-50% range and your just 24km from Mendip, then its unlikely that ' the roof aerial is still working OK', or at least something is up with part of your system. At that distance, you might even need an attenuator - 75% should be perfect, so your at the low end of workable, even on the OK channels.

Com 7 is a weaker signal with lower power, so if there is a problem, thats the canary in the coalmine. Check your system, starting back from the TV - could be something as simple as a dodgy fly lead. Then follow the path up. But it sounds like your system is just hanging on, and the probalems your getting in heavy rain point to moisture getting in somewhere, and kiling the signal. Once it dries out, it gets a bit better, but the underlying problem will not go away.

link to this comment
MikeB's 2,579 posts GB flag
S
Stephen
3:53 PM

MikeB

many thanks for your response. You seem to be saying that my roof aerial signal is much weaker than
expected. That is possible as it is over a decade old. Unfortunately access requires scaffolding which will have to wait until the building is redecorated.

Last year we lost the same channels plus a few more when one of the many local (100m away)
phone masts was ungraded. They explained that as the phone signal overloading the receiver causing it to
reduce the DTV signal so far that it could not be used (10-15% signal shown). The fix was a filter in the aerial wire. My understanding was that the filter would remove all the allocated phone frequencies. Could it be that even more frequencies are now in use and the problem has been repeated?

link to this comment
Stephen's 4 posts GB flag
M
MikeB
sentiment_very_satisfiedPlatinum

4:13 PM

Stephen: It sounds like the phone mast was being upgraded to 4G, and they gave you a filter to stop any problems - thats not the same as reducing the signal strength of your TV.

Yes, aerials can degrade, as can the connections, etc. However, start with the easiest - check the aerial lead from the back of the TV and the socket into the wall. Corrosion in the socket box, a lose cable, or a duff aerial lead can all cause problems - which are generally easily fixable. See this website for info on aerials etc Online Satellite/TV/FM/DAB Cable, Leads and Connectors sales. , and they do aerial leads to order if you like, but the 4 quid ones sound like a good deal. If it cures it, great, and no need to go up a ladder! If not, at least you know what the problem is not.

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MikeB's 2,579 posts GB flag
Tuesday, 29 November 2016
C
Chris.SE
sentiment_very_satisfiedPlatinum

2:14 AM

Stephen:
It sounds as though the effects of the 4G Phone masts haven't been explained in the best way. Any exceptionally strong signal in the same band as those you want to receive can have the effect of "desensitising" the receiver which makes it look as thought the desired signals are weaker.
As well as unwanted signals like the 4G phone ones, these exceptionally strong signals could also be the ones that you actually want to receive if you are close to a transmitter, or even if you have an aerial amplifier, you can overload the receiver if the signals were strong to start with.

MikeB has mentioned several things that can cause degradation of the signal. You say the aerial installation is more than 10 years old but that doesn't mean that it will have automatically have degraded if it was correctly installed and it was a reasonable quality aerial but Mike has made a number of suggestions of how to proceed with some basic checks, but frankly I wouldn't be paying 4 quid for a flylead just for some basic checks, you can pick them up much cheaper. If a cheap replacement reduces the signal then there's an excellent chance that there's nothing wrong with the original, but honestly I'd be surprised if you'll notice any significant difference.

Although COM7 is transmitted with a slightly lower power, there should not be significant difference in reception from Mendip at your location.
On the assumption that it is a single downlead from the aerial to just this TV set, I'd certainly check things out as Mike suggested.
You mentioned about a reduction in signal in heavy rain to 25% from 30% or so, I wouldn't be overly concerned about that if the rain is really heavy and the signal goes back up more or less immediately the rain clears - if it takes hours or even days then that suggests water getting into the aerial or cable somewhere, but what is of concern is that it is only in the 30% or so range to start with. You are high up in your location and in line-of-sight of at least 5 transmitters, but certainly should have no trouble receiving signals from Mendip (and you mentioned COM7 which is only transmitted from Mendip or Wenvoe of the 5), it would still be worth selecting your TV's Tuning menu just to be sure you are tuned to the Mendip COM7 mux on UHF Ch33.

As far as the 0% you experienced, I'm much further from Mendip than you are (and high up) and at the back end of last week I also noticed significant variation in signal strengths of some of the muxes but especially COM7 & 8 which dropped to the high 60's but is now back at the low 90's. I put this down to propagation effects and weather, as there's is definitely nothing wrong with my installation. Weather patterns have been considerably varied of late.

Even for a simple installation for Mendip, I'd still be surprised if you needed an attenuator, however if you have a more complex installation it would be best if you described it in more detail so that perhaps more detailed guidance can be given.
It's also worth just checking some basics such as the type of aerial installation and orientation. Is it pointing at Mendip - virtually due south of you (183) and are the elements horizontal? Are the elements rods or X's? How many elements are there (if X's, count each X as one)? Roughly how long is the cable from the aerial to the set? Where is the 4G Filter located?

Does your TV Tuning menu show information like Bit Errors for each mux? If so, are there any? Or does it show "Quality" information as well as Strength?

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Chris.SE's 4,101 posts GB flag
S
Stephen
12:05 PM

Chris.SE:
many thanks for your lengthy reply. By the time I got around to this last night (Monday) BBC4 HD and related had all re-appeared without any cable changes. The signal strength was 29%, what I have seen in the past for com7. The signal quality for com7 and all the other channels from Mendip is given as 100% despite signal strengths of 30-60% depending on channel.

The aerial points close to due south, at Mendip. The aerial rods are horizontal, but from memory I could not say how many there are. The aerial down-lead is about 20metres long with the filter a 1m lead away from the DTV. The weaker signal during heavy rain only lasts as long as the rain and does not continue for a day or two afterwards.

With things working again I am happy for now. Not really knowing the cause of the problem is not ideal. The jump from 29% to 0% signal strength seemed rather binary rather than a slight degradation.
I note that my signal strength seems weaker than expected at this distance and on a hill. When we next redecorate I will have the aerial and downlead inspected and replaced if necessary with the view that a stronger signal should help in the future.

Many thanks, Stephen

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Stephen's 4 posts GB flag
C
Chris.SE
sentiment_very_satisfiedPlatinum

7:47 PM

Stephen:
Hope you found the post useful.
Propagation effects can produce strange results on occasion and sometimes seem to defy logic as far as an explanation goes. My COM7 signal dropped by some 20+%, so in view of your "normal" strength it isn't too much of a surprise that yours could easily have gone to zero especially if an interfering signal from another transmitter appears. It doesn't happen too frequently that propagation changes very rapidly from one steadyish state to another but it does happen. Continuous fluctuation can be more common. However it's also worth considering the possibility of some sort of local interference. Did you have any other equipment (of any type) switched on at the time which isn't normally on. If it contains a switch-mode power supply that's not behaving itself, these can produce some very odd patterns of interference! I don't think it's too likely as such interference is usually at much lower frequencies, but nevertheless worth considering and easy to check by just switching suspect equipment on or off and checking the consequences.

As far as your aerial goes, have a look at it in daylight hours and count the elements and see what type they are. It's still possible that you might have too much signal, as Mike mentioned, if your aerial was a very high gain installed before switch-over when digital signals were much lower in strength - don't suppose you know what sort of strength your were getting back then, and if it were a different set it's sensitivity could well have been different so results may not be too meaningful.

On the other hand a 20m cable length is quite long and if it's a small lower gain aerial then this might account for the lower % strengths but I'm a bit dubious that this is the explanation for your location. Do you know what sort of signal your neighbours have been getting?

Regards, Chris.

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Chris.SE's 4,101 posts GB flag
S
Scotty
10:02 PM

Stephen, I too have lost all the COM 7 channels from Mendip. The signal is absolutely 0. Other mux are 95%. The signal is usually 95% on all channels, so maybe something's up.

link to this comment
Scotty's 1 post GB flag
S
Scotty
10:16 PM

Update, the signal on COM7 from mendip is cutting in and out now from 0% to 95%, so I guess something is being worked on. I tried two TVs and they were both the same, so its not the TVs. It could be the aerial as they are on a common one, but I guess its being reset or something.

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Scotty's 1 post GB flag
Wednesday, 30 November 2016
N
nicholas
sentiment_satisfiedSilver

1:29 AM

hI,THE use of preamps is rather debatable,as many boxes will freeze if the signal is too high,in analogue
days it was so easy to set up but this has changed,there is in most areas,interference from the power lines
due to the fact that data is transmitted over them,radio reception in many cases is spoilt,coupled with the
fact of mobile phone transmitters and other services,there is plenty to disrupt reception these days,which
pushes the average viewer to become a little tech savvy.Coupled with some dodgy tv firms who install service area aerials in secondary service areas and stick preamps in line,which cause no end of problems,it
seems solving problems has become a minefield,perhaps the easy way is to know yr local tv conditions,have
a cheap indoor aerial and see what the local field strengths are like.Freeboxes are affected by local noise
levels.Like modern cars,you will need to know more than putting the key in the ignition!!!!!!

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nicholas's 120 posts GB flag
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