Freeview: Emley Moor (U) (Kirklees, England) full-Freeview transmitter
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Freeview on the Emley Moor (Kirklees, England) transmitter

Google StreetviewGoogle mapBing mapGoogle Earth53.611,-1.666 or 53°36'41"N 1°39'57"WHD8 9TF

Transmitter fauls and engineering works

EMLEY MOOR transmitter - DAB: BBC National DAB Radio Off Air from 21:42 on 14 May to 21:44 on 14 May. BBC
Want to better understand the current TV faults? See the all new UK Free TV page


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The symbol shows the location of the Emley Moor transmitter which serves 1,550,000 homes.

Other maps:Emley Moor (U) DABEmley Moor (U) AM/FMEmley Moor regionBBC NorthYorkshire (Emley Moor micro region)

Radiation patterns

Radiation patterns withheld

Map key

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.

Emley Moor transmitter Freeview broadcasts

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. The rating shown takes in account the output power level and the various Freeview transmission modes and do not indicate an ongoing fault.

MuxEffective power level, aerial positionRatingModeWatts
PSB1
BBCA
 horizontal
Above average64QAM 8K 2/3
24.1Mb/s
DVB-T MPEG2		174,000
Channel icons
1 BBC One North, 2 BBC Two England, 7 BBC Three, 9 BBC Four, 70 CBBC Channel, 71 CBeebies, 80 BBC News, 81 BBC Parliament, 301 301, plus 12 others
• as a digital multiplex transmitted on frequency C47 (682.0MHz) from 578m datum.
PSB2
D3+4
 horizontal
Above average64QAM 8K 2/3
24.1Mb/s
DVB-T MPEG2		174,000
Channel icons
3 ITV (Yorkshire (Emley Moor micro region)), 4 Channel 4 North ads, 5 Channel 5 The North ads, 6 ITV 2, 13 Channel 4+1 North ads, 14 More 4, 28 E4, 33 ITV +1 (Yorkshire Emley Moor),
• as a digital multiplex transmitted on frequency C44 (658.0MHz) from 578m datum.
PSB3
BBCB
 horizontal
Above average256QAM 32KE 2/3
40.2Mb/s
DVB-T2 MPEG4		174,000
Channel icons
101 BBC One HD (England no regional news), 102 BBC Two HD (England), 103 ITV HD (ITV Granada), 104 Channel 4 HD North ads, plus 1 others
• as a digital multiplex transmitted on frequency C41+ (634.2MHz) from 578m datum.
COM4
SDN
 horizontal
Above average64QAM 8K 3/4
27.1Mb/s
DVB-T MPEG2		174,000
Channel icons
10 ITV 3, 20 G.O.L.D. (not free), 25 Dave ja vu, 26 Home (not free), 27 ITV 2 +1, 30 5*, 31 5USA, 34 ESPN UK (not free), 38 Quest, 39 The Zone, 44 Channel 5 +1, 72 CITV, plus 22 others
• as a digital multiplex transmitted on frequency C51 (714.0MHz) from 566m datum.
COM5
ArqA
 horizontal
Above average64QAM 8K 3/4
27.1Mb/s
DVB-T MPEG2		174,000
Channel icons
 TV News,  TV Stars, 11 PICK TV, 12 Dave, 17 Really, 29 E4+1, 32 Movie Mix, 46 Challenge, 48 Food Network, 82 Sky News, 87 Community Channel, plus 9 others
• as a digital multiplex transmitted on frequency C52 (722.0MHz) from 565m datum.
COM6
ArqB
 horizontal
Above average64QAM 8K 3/4
27.1Mb/s
DVB-T MPEG2		174,000
Channel icons
15 Film 4, 18 4Music, 19 Yesterday, 21 VIVA, 24 ITV 4, 41 Sky Sports 1 (not free), 42 Sky Sports 2 (not free), 47 4seven, 83 Al Jazeera English, 85 RT English , plus 21 others
• as a digital multiplex transmitted on frequency C48 (690.0MHz) from 565m datum.


Regional news from the Emley Moor transmitter


BBC Look North (Leeds) 1.9m homes 7.4%
from Leeds LS9 8AH, 22km north-northeast
to BBC North region - 55 masts.

ITV Calandar 1.9m homes 7.4%
from Leeds LS3 1JS, 22km north-northeast
to ITV Yorkshire (Emley Moor) region - 59 masts.

Self-help relays

Derwent BActive deflector74 homes
Derwent CActive deflector (second level)
Dunford BridgeActive deflector14 km S Huddersfield15 homes
Hmp LeedsTransposer30 homes
ThixendaleTransposer25 km ENE York40 homes

How the transmission frequencies change over time

years1956~851984-971997-981998-20112011-132013-182013-18
aerial groupVHFB EB EB EB EB EW
C10ITV
600C32com7
C34com8
C37C5C5
C40-2
C41C4C4C4+BBCB+BBCB+BBCB
C43-A
C44BBC1BBC1BBC1D3+4D3+4D3+4
C46-B
C47ITVITVITVBBCABBCABBCA
C48ArqBArqBArqB
700C49-D
C50-C
C51BBC2BBC2BBC2SDNSDNSDN
C52+1ArqAArqAArqA
C56local

orange background for multiplexes names moregreen background for transmission frequencieslilac background for power levels in watts800MHz band: 4G mobile to start in 2013700MHz band: possible 4G in 2019 more600MHz 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 7th September and 21st September 2011.

  • Ofcom have projected that a local television service for Leeds including Dewsbury, Halifax, Huddersfield, Wakefield could use an Interleaved Frequency on the Emley Moor transmitter using C56
  • COM7, COM8 projected for 2013-16. COM7 and COM8 to operate as Chesterfield, Emley Moor SFN.

Comparison of old analogue and current digital signal levels

Analogue 1-5 870kW
com7, com8(-6.4dB) 200kW
SDN, ARQA, ARQB, BBCA, D3+4, BBCB(-7dB) 174kW
Mux 1*, Mux 2*, Mux B*, Mux C*(-19.4dB) 10kW
Mux A*(-22.4dB) 5kW
PreDSO-BBCB*, Mux D*(-23.4dB) 4kW

History of Channel 3 in the Emley Moor transmitter area

May 1956-Jul 1968Granada Television†
May 1956-Jul 1968Associated British Corporation◊
Jul 1968-Oct 2002Yorkshire Television
Oct 2002-Dec 2014ITV
• Breakfast ◊ Weekends ♦ Friday night and weekends † Weekdays only.


Your comments: most recent posts are at the bottom

firstFirst comments prevEarlier comments  ◊  Later commentsnext Latest commentslast

Your comments are always welcome. Please use the form below to add your thoughts or questions to this page. We will get back to you as soon as we can.

Steve
Monday 26 September 2011 9:10PM
Emley Moor broadcasts ITV HD (Granada). There is no Yorkshire service - there are only a few regions and each transmitter is assigned the nearest.
bryan phillips-martin
Tuesday 27 September 2011 12:40PM Worksop
living in S81 9NA what is the best waveband for me
Martin
Tuesday 27 September 2011 7:31PM Knaresborough
I am now very confused... HD signals chanel 41 on the emly moor transmitter are supposed to be on Chanel 41 yet the published HD date is September 26 2012 - a year away what is going on? IS it possible to receive HD signals in the Harrogate area?
Martin
Tuesday 27 September 2011 7:37PM Knaresborough
Confused of harrogate is even more confused.. Sheffield ( a satelite of Emly moor) has HD!!! Why don't I?
KMJ,Derby
Tuesday 27 September 2011 8:01PM
Martin: You are predicted to be able to receive Freeview HD at the present time, as long as your aerial is pointing to Emley Moor (SSW at 195 degrees) and you have a Freeview HD box or IDTV capable of supporting DVB-T2 signals. The date for HD transmissions beginning from Bilsdale is 26th September 2012.
Martin
Tuesday 27 September 2011 8:12PM Knaresborough
Hi KMJ Derby, just ot et you know (I think my last post failed) I have an Ariel pointing at Emley with Distribution booster to upto 6 points in the house (only 2 used) The main TV has a Humax 9300T interfacing to the TV via HDMI link. The only component that does not match is the cabling ie it is standard coax with Coax connectors (Not F-Type)
Martin
Tuesday 27 September 2011 8:17PM Knaresborough
Additional Info - Signal 90% Quality 80%
jb38
Tuesday 27 September 2011 8:23PM
bryan phillips-martin: Belmont (@ 39mls) is indicated as having the edge on Emley Moor (@ 29mls) for reception at the location given, this of course totally dependant on any adverse local conditions that may apply, as predictors cannot really cater properly for these type of situations.



Briantist
Tuesday 27 September 2011 8:25PM
Martin: 2012 date is for Bilsdale transmitter. Have you seen www.ukfree.tv link icon What does "Full HD Ready" actually mean? | ukfree.tv - independent free digital TV advice .
Martin
Tuesday 27 September 2011 8:44PM Knaresborough
Briantist, all devices claim to be "HD ready" Have read the other articles suggested. Have also in the meantime tried a factory reset. all to no avail stll cant pick up any HD chanels on any device.
Briantist
Tuesday 27 September 2011 9:06PM
Martin: The point being, you need a "DVB-T2" receiver to get Freeview HD, anything else will not see the channels.
jb38
Tuesday 27 September 2011 9:28PM
Martin: As has been said by others, you require a device with a DVB-T2 tuner and the Humax doesnt have one as its not an HD recorder, nor does it suggest that it is.

The other point is that an HDMI connection doesnt automatically mean that the device that has it is capable of HD, as its only another more sophisticated type of connection.

If you can give the model of the TV in question this can also be verified if its capable (or not) of HD reception.
Martin
Tuesday 27 September 2011 9:28PM Knaresborough
Briantist - I guess that's where I was working too thanks all the same.
glenn
Saturday 1 October 2011 3:52PM
no 5.1 on itv
mike woodward
Monday 3 October 2011 6:31PM
Hi. I am in huddersfield & had no problems before analogue switch off. Since then i have problems last week with all BBC channels. Today BBC is unwatchable & all other stations are unrelaible & constantly breaking up. What happend to increased power?
Robert Hill
Monday 3 October 2011 9:29PM
Mike Woodward at the time of posting all muxes are all ok,in fact watching BBC 1 . Location 3 miles south of Wetherby.
mike woodward
Tuesday 4 October 2011 9:07AM
Hi Brian
Thanks for your reply. When you sent your reply last night my service was also fine, with good signal strength. This morning it is still good but the signal is continually fluctuating from excellent to ok to good and so on. Obviously I am only really interested in a good picture, regardless of signal indicator. However, I am regularly unable to watch since the DSO because of picture breakup. It is so unreliable. Should the signal strength be fluctuating so much and at varying times of day?
richard caywood
Tuesday 4 October 2011 9:22AM Leeds
whats happening with challenge No46 .... Changed the holiday teletext.. ????? Has it gone or moved
Dave
Tuesday 4 October 2011 9:32PM
Mike, I wonder if you are really tuned to Emley Moor and not another transmitter? I live near Goole and am able to pick up transmitters on the Isle of Mann, North West and Belmont (Lincs) as well as Emley Moor. My Humax recorder makes a real mess of trying to pick the correct signals as they are all very strong.

I had to resort to manual tuning and now all is well.
mike woodward
Thursday 6 October 2011 7:05AM
Just an update on my reception. I have fitted an aerial booster which appears to have stabilised the reception and sorted out the fluctuating signal on groups 1&2. Thanks to all of you who responded and for your ideas. Very much appreciated. Mike
dave
Friday 7 October 2011 8:45PM
Hi there,

I'm no longer receiving Dave, sky news etc all of which are on the COM5/ArqA Mux. Is this most likely due to a fault with the aerial either not in the right orientation or something else?

Thanks in advance.
Mark Fletcher
Sunday 9 October 2011 3:09PM Halifax
dave.Friday 7 October 2011.8.45pm.Difficult so say without a postcode,but is your aerial vertical or horizontal polarisation,and what group is your aerial,also is your broadcasting area Emley Moor or Belmont !
dave
Sunday 9 October 2011 5:59PM Leeds
Mark Fletcher. Thanks for your response, sorry I completely forgot that information would be useful. Postcode is LS2 8AR and I'm receiving from Emley Moor. The aerial is vertical polarisation. I was receiving those channels but not since the retune, however I wouldn't have thought that would be an issue.
Betamax_man
Sunday 9 October 2011 6:12PM York
@Dave. If your aerial is vertically polarised you will probably be using a relay not Emley Moor. Emley Moor is horizontally polarised.
Steve
Sunday 9 October 2011 6:29PM Leeds
dave - your postcode indicates that if you are on a relay transmitter it would most likely be Beecroft Hill; this is a Freeview Light transmitter and has never had these channels. You may have picked them up from a more distant mast but it seems if you want them you will have to switch to Emley Moor if it is possible in your location. I suggest looking around at neighbouring aerials and/or a word with a local engineer.
Mark Fletcher
Monday 10 October 2011 1:58AM Halifax
dave.LS2 8AR.Your postcode denotes Crown Plaza in or out of Leeds city centre,and as you stated the aerial is vertical polarisation which Steve of Leeds points out that you're receiving the Beecroft Hill relay transmissions which is a light relay broadcasting three mux's BBCA,D3+4,BBCB and a future fourth mux local some time in the near future.Are Crown Plaza low/high-rise flats/apartments,and if so is the aerial fitted externally (communal type possibly) or do you have an aerial for yourself either an external one or an internal set-top type.If the external antenna is communal,then you will need your landlords consent to have it realigned,if yours then you can if you wish realign it yourself to receive either Emley Moor or possibly Belmont (polarisation will have to be changed to horizontal to receive the before mentioned main transmitters above).Just one note,if you decide to pick up Belmont as a last resort,first two of their mux's ArqA on ch 53 and ArqB on ch 60 both currently on 4kw (both increasing to 100kw after Wed 23 Nov 2011),is for now out of reach until Tacolneston switches over fully on Wed 23 November 2011 due to frequencies 53 & 60 there currently clashing with each other.Secondly Belmont broadcasts BBC1 East Yorkshire and Lincolnshire news bulletins,as well as ITV1 Calendar (East) with more East Yorkshire and Lincolnshire matters.If you did decide to opt for Belmont as a last resort,best bet is to wait until after Wed 23 Nov 2011,when Tacolneston becomes all digital and the two currently understrength Belmont mux's ArqA & ArqB increases in power up to 25 times from that date onwards.
John Thorndike
Wednesday 12 October 2011 5:02PM Wakefield
Since change over to digital only signal I tend to suffer from screen freeze and from "no or weak signal". This never happened with the old system.
Improvement means rubbish service,,,,,,AGAIN

John Thorndike
Wednesday 12 October 2011 5:02PM Wakefield
Since change over to digital only signal I tend to suffer from screen freeze and from "no or weak signal". This never happened with the old system.
Improvement means rubbish service,,,,,,AGAIN

KMJ,Derby
Wednesday 12 October 2011 8:20PM
John Thorndike: The Digital Uk postcode checker shows you are predicted to have excellent reception from Emley Moor on all six muxes. Check that the correct set of channels have been stored, as it is possible that weaker signals from Bilsdale or Belmont were found first during the scan and those channels stored in the "normal" positions in the channel list. If so, Emley moor channels might be stored in the 800s. If this is not the problem, do you have amplification ( a booster) on the aerial? If you do, there might be too much signal following switchover, this results in an apparent weak signal/ poor quality being indicated. If removal of the booster or turning down the gain is not possible, fit an attenuator in the aerial feed to deliver a usable signal strength.
David
Wednesday 12 October 2011 10:01PM
This week on misty/fog mornings I'm getting breakup on Sky News from EM.
Dave Lindsay
Saturday 15 October 2011 1:10AM Doncaster
I have an issue with one receiver freezing, when two others that are connected to the same aerial do not.

My Sony RDR-HXD870 freezes I estimate on average every five or ten minutes on C51 (less often on others). Yet the Panasonic TU-CT41 and Hauppauge TV USB dongle don't.

The Hauppauge software has a signal monitor with it and it shows how many errors. When the Sony breaks-up, no errors (correctable or uncorrectable) are shown by the Hauppauge software.

The devices are connected by short 1.5m leads so are not far apart. The Sony does it when it's the only device turned on.

Does the fact that two devices work fine suggest that the aerial and downlead are fine in my location?


The aerial is a 10 element contract wideband fitted in the loft. The downlead is a 10m long crappy coax (silver foil screen with 8 silver conductors!).

It was a DIY purchase from Argos around 15 years ago and has worked perfectly picking up DTT pre-DSO.

I know that it's a poor aerial, but could it be the cause of one receiver having problems when two others don't (on the same channel at the same time)?


I have tried attentuation and it makes no difference. Signal strength given by the Sony (without attentuation) varies between muxes: 70% to 92%
Mark Fletcher
Saturday 15 October 2011 12:44PM Halifax
Dave Lindsay,Doncaster.I take it your aerial is horizontally polarised,and if so is it pointed towards Emley Moor,or Belmont.The reason pardon my inquisition is that Doncaster where you reside can receive either Emley Moor or Belmont transmissions.Firstly you stated that your contract group W wideband aerial is inferior,i suggest you replace it in due course for a much superior aerial.ATV (Aerials & Television) of Sheffield,are a highly recommended aerial retailer who only sell superior quality aerials in all groups A,B,C/D,K,E,W (dependent on the mast concerned),don't bother buying a new aerial from Argos,B&Q,Wickes or any other DIY store,nor the likes of Labgear,Philex,Maxiview,etc,they're all cheap inferior contract group W wideband aerials.Also the 15 year old Argos bought cheap crappy co-ax you mentioned does need replacing with a much superior double screened copper/copper CAI approved cable (black coloured preferred,but brown will do,white not recommended) with a much superior brass co-ax plug, (not silver,alloy or worse plastic co-ax plugs the're useless).Again ATV of Sheffield stock the above mentioned.
jb38
Saturday 15 October 2011 4:35PM
Dave Lindsay: No two devices have the same sensitivity, and the problems you are having with the Sony is likely because its a bit less sensitive and as such demands a better signal, the signal indications you have given not being particularly sparkling considering the power that Emley Moor is transmitting on.

You could maybe clarify another point though, this regarding the problem being seen when only the Sony is switched on, are you meaning when the aerial is only connected to it and nothing else? because if the aerial is still coupled to the other devices then try it whilst its disconnected from them, as you haven't said anything about the method used to split the aerial between these devices, and if you are using some form of passive splitter then the more that's connected into it the less the signal will be to each device, this applying whether they are switched on or not, powered splitters always being best for this type of thing unless a person sited within a very strong signal area not that far away from the transmitter, you being 25 miles away from Emley Moor.

That said though, I feel that irrespective of answers given the situation could likely be improved by spending some time on re-positioning your aerial within the loft, as most people who fits an aerial into a loft usually plumps for the easiest spot to fix it in, irrespective of the fact that it might not necessarily be the best spot for the signal.

On the subject of the aerial, if it was working OK before switchover then there is no reason whatsoever why it shouldn't be now "if" you are picking up from the same station as before, as since analogue days right up to the present your aerial has always been a group B.

You could probably benefit by replacing the co-ax though!

Dave Lindsay
Sunday 16 October 2011 12:38AM Doncaster
Briantist: Thanks. I read the page about too much signal being bad a while ago and as a result, was reminded of it when I experienced repeated freezing. I got a variable antennuator (like the one shown in the photograph on that page) and even when the signal strength is attentuated to around 40% (from about 85%) on the most troublesome mux, it makes no difference.

jb38: You have confirmed the conclusion I was coming to: That is that it is an aerial/downlead problem. I'm now using another aerial and it's working just fine.

What threw me was the fact that the Panasonic and Hauppauge work perfectly fine (connected to the same aerial, tuned to the same channel at the same time). That is, listening to all three devices at the same time, only the Sony breaks-up. However, I do appreciate that not all devices are identical.

There is another loft aerial for another room and I've run a coax extension from there to the Sony's input (which was fed from my aerial). So far, so good, no break-up, even though the strength from that aerial is 85% (with no attentuator).


The reason I introduced the passive splitter was so as to allow the amp in the Sony to be turned off when it's in standby. Thus, if it didn't work (using the splitter), then there would be no need to get a powered one because I have one! (All devices are within a metre or so of one another.)

This aerial worked just fine pre-DSO, even during the snow.

I think that the most likely cause is reflections caused by a large warehouse (nearly half a mile long) which was built a number of years ago (ghosting appeared at that time). It is a couple of miles away at about 140 degrees from the direction that the aerial faces. The rooftop aerial also suffered from ghosting on analogue.

It was particularly bad (not terrible by any means though) with my loft aerial on BBC Two analogue, which was on C51, which is now occupied by the mux that is freezing the most. I think it's fair to assume that any such reflected digital signals would have been small (negligible maybe) pre-DSO and increased considerably now.

I remember watching the snooker on analogue (on BBC Two) and seeing a dark impression of the queue ball part way over the screen from the proper one. Does this suggest an inverted reflection?


Mark Fletcher: When I retuned at DSO, I made sure that my tuners were on Emley Moor. Sometimes they do get Belmont. In the past with analogue I tuned presets 5 to 9 (or 6 to 10) to Belmont. Even with the aerial being in the opposite direction, it came in quite strong.

Most Doncastrians seem to be on Emley, except for a few places where the topography doesn't allow. Belmont broadcasts different local news so I would never consider it unless there was no other option.

I've looked extensively at ATV's website. It's excellent with lots of information on how things work, as well as the online shop.

The reason for the DIY purchase from Argos in the early 90s was because that was the only real option! Now the internet has come along, there are many more choices.

I don't hesitate when say that I wouldn't buy the cheap DIY crap again!
Thomas
Monday 17 October 2011 7:11AM
Since switchover, I've had hardly any break-up or No Signal conditions on my Freeview sets. I'm still waiting for a very windy day though, to see if the TV can tolerate it now that the signal strength is better...
I think it may even be slightly too strong, as I have the issue with my Panasonic TV showing quality as very weak then jumping up to full.
Brian Springthorpe
Tuesday 18 October 2011 6:20PM
I have a question for Briantist.

In Penmaenmawr in North Wales the number of Freeview channels that we get is probably a complete list, including all the +1 hour and Film 4 and Dave etc.

We regularly go upto the Yorkshire Dales and the Lake District on walking holidays and either stay over in pubs or rent a cottage. We have just come back from a very nice break in Kirkby Lonsdale.

When I switch the provided televisions on in these regions, there isn't the same comprehensive listing that we get here in North Wales. It was noted that chaneels such as Film 4 and Dave plus a load of others were missing from the list. What you would call the major channels, such as ITV1, which normally have a +1 hour channel running, were there but ITV2, 3 and 4 didn't.

I tried retuning but could only get those channels. I checked the parental settings on the TV but the settings were witched to off.

So why can't we watch Film 4 or Dave etc. in Kirkby Lonsdale?

We are going back there in April next year. If its a matter of taking a set top box to cure the problem I can manage that, but I suspect it is something more.

Please help!
Steve
Tuesday 18 October 2011 6:37PM Kendal
Brian - if you were picking up from Kendal Fell relay mast in Kirkby Lonsdale (the nearest) then this is a Freeview Light transmitter and only has the public service channels - see the transmitter details on this site. If you could pick up Lancaster then this has the full range. Clue - Lancaster broadcasts Granada ITV, Kendal has Border.
mike Roberts
Wednesday 19 October 2011 6:04PM Wigan
HI why is it I have good signal strength from the ITV and BBC multiplexes, and weak signal from the rest of of them like the ITV3 multiplex. I realise i am out of the Emily more area but I thought they were all at the same strength now? I am In Aspull Wigan WN2 1SZ
Brian Springthorpe
Wednesday 19 October 2011 7:21PM Carnforth
Steve,

Can KL actually see the Lancaster transmitter?

KL is so low in the LUNE Valley and the fells seem quite high on the south side.

Do you know anyone for certain that is pointing at Lancaster from Kirkby Lonsdale?
Briantist
Wednesday 19 October 2011 8:54PM
mike Roberts : You should be using the Winter Hill transmitter, from which you will receive all services at full strength.
mike Roberts
Thursday 20 October 2011 1:16AM Wigan
hi Briantist yes i am aware my local transmitter is winter Hill but was just wondering why certain multiplexes from emily moor were weaker then others when i thought they were all now at the same strength.
Briantist
Thursday 20 October 2011 1:52PM
mike Roberts : They are all at the same strength in terms of ERP, but the radiation patterns may not be identical.

However, I don't actually know or not, because the information was redacted as a "state secret" when I asked the BBC for the information.

You may also have interference from other transmitters on the same frequencies.
Mike Dimmick
Thursday 20 October 2011 3:22PM
mike Roberts: A number of propogation conditions can mean different frequencies travel more or less well. In general, the higher the frequency, the less it bends over terrain, so you would normally expect - from the wrong side of the Pennines - that the higher frequencies will be less strong than the lower ones. In addition, reflections - causing multiple paths from the transmitter to your aerial - interact differently with different wavelengths (the difference in path length is a different number of wavelengths at different frequencies) and therefore their effect on signal strength can cause changes through measurement.

The power levels as stated are envelope power limits, not absolute limits. In the worst case the different carriers making up the signal could all align the same way at one instant, or all different directions at another instant - the difference between these two conditions is potentially 76 dB! In practice the peak-to-mean ratio is clipped at 7-10 dB, but this is still enough for programme content to mean that different muxes with the same nominal maximum power output read at different levels (source: www.bbc.co.uk link icon BBC RD - Publications - White Paper 156 DVB-T and Voltage Ratings of Transmission Equipment ).

Really, the box should measure the size of the pilot and TPS carriers, which do *not* change amplitude (though they do change phase), rather than the whole bandwidth, but that is the customary approach.

Finally, as Brian says, there may be differences in the radiation patterns. The radiation pattern of a full transmitting antenna is made up by combining many smaller elements. The UHF aerial for Emley Moor's second mast (this collapsed before the current tower was built) was eight tiers of 6 panels, each panel carrying 4 elements (8 *components* were fitted to each panel, but the active part was the vertical slot *between* the components, odd as that may sound). Again, the slots behave slightly differently at different frequencies - optimal resonance is achieved at 1/4 of the wavelength, so you can never tune the response of an aerial carrying more than one service perfectly for all of them. The overall radiation pattern is made up by the reinforcing and cancelling signals from each element on each panel.

That original antenna contained transformers to feed only 60% of the power into the two panels in each tier on the south-west face, compared to the other two faces. Pushing any more power into the Pennines was considered a waste. You can see the BBC's report on that antenna at www.bbc.co.uk link icon BBC RD - Publications - R&D Report 1966-47 : UHF transmitting aerial for the Emley Moor Television Station , particularly how its radiation pattern differed at C44 (BBC One) and C51 (BBC Two).

Because the Emley Moor tower is now a listed building, the external appearance had to remain the same even while changing the antennas inside the fibreglass shrouds at the top of the mast. In turn, though, that meant that Arqiva didn't have to apply for planning permission to change the antennas as they had at most other sites. So we don't know anything about what the new aerial is like and what its radiation pattern might be.
Dave Lindsay
Thursday 20 October 2011 5:40PM
Mike Dimmick: That document is interesting. Why might they have decided to implement differing radiation patterns for the two channels? What was the point of this?

The chart published elsewhere by UK Free TV showing the number of homes served by Emley Moor indicates that not all will receive both PSB and commercial muxes:

www.ukfree.tv link icon The commercial multiplex after switchover: ArqA, ArqB and SDN | ukfree.tv - independent free digital TV advice

Presumably some at the fringes will only be able to receive the PSBs.

This is despite them all being listed as having the same ERP of 174kW.

Is this evidence that the radiation patterns of the PSBs and Coms are different? (DN31NJ)
mike Roberts
Thursday 20 October 2011 5:50PM Wigan
HI mike is it different then for FM radio? as west yorkshires local radio station the pulse, signal travels well into Greater Manchester as far has Bolton and beyond, you would be able to get it here if wish Fm was not more or less on the same frequency which is 102.5 which is fairly high up on the FM frequency list.
Mike Dimmick
Friday 21 October 2011 4:40PM
mike Roberts: As FM radio is on a lower frequency, it bends more over terrain and so can travel further than UHF television.

The radiation patterns for radio transmitters *are* published by Ofcom, and you can see the one for Emley Moor at www.ukfree.tv link icon FM, MW and LW radio broadcasting | ukfree.tv - independent free digital TV advice . However, The Pulse broadcasts from Vicars Lot, a site several miles to the west and omnidirectional: www.ukfree.tv link icon Vicars Lot analogue radio transmitter | ukfree.tv - independent free digital TV advice .
Mike Dimmick
Friday 21 October 2011 5:04PM
Dave Lindsay: The antenna would have been designed to minimize the differences between channels, but it's an inevitable consequence of having multiple channels share one aerial, that the radiation pattern of each channel is a bit of a compromise.

The picture is somewhat exaggerated as engineers normally measure differences in decibels (dB) while those graphs are shown in relative volts. To convert, take the base-10 logarithm of the voltage ratio ('log' on most calculators, LOG10 in Excel) and multiply by 20.

Giving each channel its own antenna at the same site would still be a compromise, as the coverage area is also affected by the aerial's height. Each antenna could be shorter - fewer tiers - to reduce the differences in height, but that would reduce the gain of the aerial and increase the electrical power needed to produce the same output.

In the US, it seems to be common to erect a tower with quite a wide platform that the various antennas then are mounted on - where they do share sites at all. The Empire State Building is festooned with different aerials.

As it is, the commercial multiplexes at Emley Moor are on an aerial slightly further down the mast (about 11.5 metres) than the PSB multiplexes, presumably so that each can be optimized better for the frequencies it's carrying, though it will also offer greater redundancy. The other issue is that the commercial muxes clash more with transmissions from other sites (e.g. Nottingham also uses 48/51/52) and with PSB transmissions from the relay transmitters - both co-channel, using the same channel at both sites, and adjacent-channel interference, due to the imperfect nature of the transmitter - some power leaks into adjacent channels. It is filtered, but filters with a less sharp roll-off are permitted at lower-power sites, therefore more leakage. This only affects the residents near to that site, but it still ends up reducing coverage.

There's a possibility that Emley Moor ArqB might currently be restricted to half power to avoid damage to the low-power Mux 1 at Pontop Pike - there is provision for that in Ofcom's licence documents.

Signal propogation is slightly frequency-dependent, and higher frequencies don't travel quite as well as lower ones, nor carry along cables quite as well. I also mentioned multi-path effects before.

All this put together means you may see different levels across the various multiplexes, and those differences may change over time, despite the published maximum ERPs being identical.
Dave Lindsay
Sunday 23 October 2011 10:08PM
Mike Dimmick: Does each mux have its own set of panels then?

Why the gap of 11.5m?

I assumed that underneath the fibreglass shroud there would be rows of panels (without gaps) similar to these being installed at Sandy Heath:
tx.mb21.co.uk link icon mb21 - The Transmission Gallery (DN31NJ)



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