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Full Freeview on the Mendip (Somerset, England) transmitter

first published this on - UK Free TV
sa_streetviewGoogle Streetviewsa_gmapsGoogle mapsa_bingBing mapsa_gearthGoogle Earthsa_gps51.237,-2.626 or 51°14'12"N 2°37'33"Wsa_postcodeBA5 3LB

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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.

This transmitter has no current reported problems

The BBC and Digital UK report there are no faults or engineering work on the Mendip (Somerset, England) transmitter.

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

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
C49 (698.0MHz)591mDTG-3100,000W
Channel icons
1 BBC One West, 2 BBC Two England, 9 BBC Four, 120 CBBC, 121 CBeebies, 130 BBC News, 131 BBC Parliament, 601 BBC RB 1, plus 17 others

PSB2
D3+4
 H max
C54 (738.0MHz)591mDTG-3100,000W
Channel icons
3 ITV (West), 4 Channel 4 South ads, 5 Channel 5, 6 ITV 2, 13 Channel 4 +1 South ads, 14 More4, 15 Film4, 24 ITV4, 28 E4, 33 ITV +1 (West),

PSB3
BBCB
 H max
C58 (770.0MHz)591mDTG-6100,000W
Channel icons
45 Film4 +1, 101 BBC One HD (England no regional news), 102 BBC Two HD (England), 103 ITV HD (ITV Meridian Southampton), 104 Channel 4 HD South ads, 105 Channel 5 HD, 123 CBBC HD,

COM4
SDN
 H max
C48 (690.0MHz)591mDTG-8100,000W
Channel icons
10 ITV3, 20 Drama, 21 5 USA, 26 ITV Be, 27 ITV 2 +1, 30 5STAR, 34 ITV3 +1, 37 Quest, 44 Channel 5 +1, 54 My5, 58 ITV Be +1, 61 True Entertainment 1, 62 ITV4 +1, 66 CBS Reality, 70 Horror Channel, 83 Blaze, 84 Blaze +1, 122 CITV, plus 16 others

COM5
ArqA
 H max
C56 (754.0MHz)591mDTG-8100,000W
Channel icons
11 pick, 12 Dave, 17 Really, 29 E4 +1, 32 Sony Movie Ch, 38 Quest Red, 41 Food Network, 46 Challenge, 48 Movies4Men, 68 truTV, 69 Tru TV +1, 72 YourTV, 132 Sky News, plus 12 others

COM6
ArqB
 H max
C52 (722.0MHz)591mDTG-8100,000W
Channel icons
18 4Music, 19 Yesterday, 25 Home, 31 Spike, 42 Travel Channel, 47 4seven, 59 BT Showcase (not free), 64 CBS Action, 71 CBS Drama, 73 YourTV +1, 79 Dave ja vu, plus 19 others

LBS
 H -10dB
C51 (714.0MHz)591mDTG-1210,000W
Channel icons
from 22nd September 2014: 7 Made in Bristol,

com7
 H -1.4dB
C33 (570.0MHz)591mDTG-672,400W
Channel icons
56 5USA +1, 57 VIVA, 67 CBS Reality +1, 81 Talking Pictures TV, 82 Vintage TV, 87 Keep It Country, 106 BBC Four HD, 107 BBC News HD, 108 Al Jazeera Eng HD, 109 Channel 4+1 HD, 110 4seven HD, 113 RT HD, 124 CBeebies HD, plus 2 others

com8
 H -1.6dB
C35 (586.0MHz)591mDTG-669,100W
Channel icons
55 5STAR+1, 63 Community Channel, 86 More4 1, 91 Front Runner TV, plus 4 others



DTG-3 64QAM 8K 2/3 24.1Mb/s DVB-T MPEG2
DTG-6 256QAM 32KE 2/3 40.2Mb/s DVB-T2 MPEG4
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
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
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?

years1984-971997-981998-20102010-1327/3/13-2013-1730th Jun 2019-
aerial groupC/D EEEC/D EC/D EWK
600C32BBCA
C33com7D3+4
C34BBCB
C35com8SDN
C36ArqA
C37C5C5
C48SDNSDNSDNArqB
700C49 BBCABBCA
C51LBS
C52ArqBArqBArqB
C54C4C4C4D3+4D3+4D3+4
C55+2
C56+CArqAArqAArqA
C58BBC1BBC1BBC1BBCBBBCBBBCB
C59+1
800C61ITVITVITVBBCA
C62+A
C64BBC2BBC2BBC2
C65+B
C67D

orange background for multiplexes names more
green background for transmission frequencies
lilac background for power levels in watts
800MHz band: 4G mobile started in 2013
700MHz band: 4G from 30 June 2020more
600MHz band: new or moved digital TV services more
Notes: + and - denote 166kHz offset; aerial group are shown as A B C/D E K W
Italics for analogue, digital switchover was Wednesdays 24th March and 7th April 2010.

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
Tuesday, 29 November 2016
C
Chris.SE
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?

link to this
Chris.SE's 18 posts GB
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

link to this
Stephen's 4 posts GB
C
Chris.SE
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.

link to this
Chris.SE's 18 posts GB
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
Scotty's 1 post GB
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.

link to this
Scotty's 1 post GB
Wednesday, 30 November 2016
N
nicholas
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!!!!!!

link to this
nicholas's 57 posts Bronze Bronze GB
N
nicholas
1:41 AM

Hi,as in analogue days,a lot of locations have difficult receiving problems,generally outside the primary
service area,fading problems can be chronic,very much like the old days on band 1 bbc,some transmitters
by virtue of their location had many problems in their service areas so the problem has again reared its
ugly head.

link to this
nicholas's 57 posts Bronze Bronze GB
Thursday, 8 December 2016
M
Martin
8:59 AM

I see that you predict that post B700 Mendip will use 22/25/28/40/43/46. I'm just wondering where those figures come from....?

link to this
Martin's 15 posts GB
S
Stephen
2:58 PM

Scotty:

after working all last week Mendip com7 cut out again for me Sat 3rd to Mon 5th, and returned at its normal strength on Tuesday. A similar pattern two weekends in a row. Do you see something similar?

If not perhaps it is local interference as Chris suggested, maybe related to several neighbors who work away in the week.

link to this
Stephen's 4 posts GB
Friday, 9 December 2016
C
Chris.SE
7:58 AM

Stephen: I would say that the fact that you noticed this problem 2 "weekends" in a row is just coincidence. As I mentioned this is much more likely to be atmospheric conditions changing the propagation of UHF signals and distant signals from other transmitters on the same UHF channel starting to cause interference, which in simple terms can have the sort of effect we saw.
Remember that more than one of us happened to observe the issue, Scotty being the most recent, and no Transmitter engineering work was taking place - one of the first things I checked on the engineering pages - AND it would have been reported here on these pages as well, also if there had been a fault. See page 153 for the last reported issue on October 4th.

One thing I didn't mention (so as not to confuse people with less technical understanding of propagation effects) was that there was definitely a "lift" (as it can be called) on, when I was checking signals previously around that weekend as I was periodically picking up signals from another (distant) transmitter on other UHF channels which are not normally present. It was one of the ones I can regularly get when there is a "lift". There were similar conditions a couple of weeks earlier that I happened to spot (Tues.15th) when I was doing some re-tuning. In the days of analogue transmissions, people could notice such things more readily in the form of picture interference/patterning/foreign pictures - this sort of effect can be more common in the summer and some may recall mentions of "continental interference" at such times.

I mentioned "local" interference as it's always worth trying to check that there wasn't something else having an effect at the time to compound matters, but your fundamental problem Stephen is that your "normal" signal is low - in this 30% range, so any sort of "lift" or "interference" can knock out the signals more readily. Another reason I suggested checking what sort of signals your neighbours are getting is there may be very local conditions giving a "reduced" signal, examples of which can be tall buildings or other structures in or near the line of sight, tall trees etc.
As well as checking that you now don't have a fundamental problem with your aerial/cable installation causing a weaker signal (as previously mentioned by Mike and myself) you also need to check that you don't have too strong a signal as this can "desensitise" the receiver or, as you are already aware - a close phone mast having this effect. But remember all those sort of issues are likely to have an effect on reception of all your muxes rather than just one.

The situation with Scotty is slightly different in that he says he normally has 95% signal, but location - which way the aerial is pointing etc, and again the precise local conditions (buildings, trees etc) can have an influence on what is received.

Martin: The allocation of UHF channels for the various muxes at all transmitters is defined/stated in various OFCOM documentation.

link to this
Chris.SE's 18 posts GB
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