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Aerial Pole and Bracket Tests

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Belmont

Bilsdale

Black Hill

Blackburn in Rotherham

Bluebell Hill

Burnhope

Chesterfield / Unstone

Craigkelly

Crosspool / Sheffield

Crystal Palace

Dronfield

Emley Moor

Hannington

Heathfield

Holme Moss (radio)

Keighley

Keighley Town

Mendip

Moel Y Parc

Moorside Edge (MW radio)

Nottingham

Oughtibridge (a typical repeater transmitter)

Oxford

Pontop Pike

Ridge Hill

Rowridge

Sandy Heath

Sheffield / Crosspool

Sheffield (MW radio)

Stocksbridge / Hunshelf Bank

Sudbury

Sutton Coldfield

The Wrekin

Totley

Waltham

Wincobank

Winter Hill

Notes


All the pictures of the transmitters (TXs) are to scale.


The heights of the structures are estimates. Different sources give different heights, some of which seem to include the transmitting array(s) at the top, and others don`t. In fact the only mast which I`m certain of the height is Waltham, because I`ve seen the actual plans for the layout of its transmitting antennas ! On the subject of Waltham, there are three other TXs of the same design, Winter Hill (in the graphic above), Bilsdale and Mendip.

Belmont is also similar, it`s just even taller and has six sets of stay levels, or did have till they shortened it up to April 2010.


The height of our shop is to the top of the roof.


I was going to put an extra line in "Number of Asprin required if the object hit you", but there were too many variables. For instance, would a child need Junior Asprin ?


The times in the above table for the object to hit the ground are calculated in free space. Obviously these structures are not built in vacuums, but if the object being dropped was made of a dense material (like a spanner for instance....) I wouldn`t have thought the calculated figures would be that far out. In fact,  in August 2011, John Sager did some calculations (of the time and velocity reached) taking into account the effect of air resistance/drag. The example was of a spanner, a 19mm combination spanner (weight 138g) in fact. To simplify matters it was assumed that the drag was similar to a piece of metal strip 225mm x 20mm x 5mm, these equate to the average dimensions of the spanner. John did two sets of calculations, the first if the spanner was falling "end on", and the second if it were falling "side (flat) on". This makes a big difference because the drag is proportional to the frontal area of the object.

For what it`s worth I reckon the spanner may well fall open end first because there`s more drag on the (opposite) ring end, and in addition there`s a weight bias toward the open end.

Belmont  385m  (as originally built, now 351m)

Emley Moor 328m

Waltham 314m

Bilsdale 309m

Winter Hill 309m

Black Hill 307m

Mendip 280m

Moel Y Parc 240m

Sandy Heath 240m

Burnhope 229m

Holme Moss 228m

Sutton Coldfield 225m

Crystal Palace 222m

Oxford 160m

Ridge Hill 160m

Sudbury 160m

Pontop Pike 154m

Hannington 154m

Heathfield 145m

Rowridge 135m

Craigkelly 135m

Relative heights of the other major structures on this site.

Also see How High is High ? and Emley v Belmont v Taipei 101.

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Coverage Maps / Postcode Reception Predictors


This site does not provide TV transmitter coverage maps because at best they are misleading and at worst they are downright inaccurate !

On a more general level the use of coverage maps and postcode predictors can be misleading because they cannot conceivably take into account local conditions (e.g. trees or high buildings) and they over emphasise distance to the transmitter. Any professional installer will tell you the over riding importance of the former and the relative lack of importance of the latter, see signal levels. For instance if a locality has a choice of two different main transmitters, one 10 miles away through a bleedin` great tree (or high building) and one 40 miles away but with clear line of sight, any installer worth his salt will choose the latter of the two options.


You`re better off working out your own signal strength.......

And which transmitter to use......


The Digital UK postcode predictor is probably the most widely used. There are a few things to bear in mind when using it. Always tick "Detailed view", this brings up far more information. From November 2011 by hovering the cursor over the channel number it brings up the transmission power, which can be well worth worth knowing.

Post code predictions can sometimes be highly amusing, and this is particularly the case in sparsely populated areas where the geographical areas are larger. e.g. our test site. In fact a reception predictor (pre DSO) for our test site advised a “High Gain” or even an `Amplified Extra High Gain` aerial, yet even before the switchover power increase the signal levels off Emley were too large, and that was off a DM Log !

Infamously we once got a call (pre switchover) from a customer near Owler Bar on the outskirts of Sheffield who`d been advised by the checker that she couldn`t get digital. But the Owler Bar is over 1000ft in altitude, on the NE side of a mountain facing Belmont, so what do you think ? ! ? In fact she could probably have picked up the low power pre switchover signals from Bilsdale and Crosspool (Sheffield), with a chance of Emley Moor as well !


The table below tells its own story, try using some of the coverage predictors with these post codes, see how accurate, or not, they are !

Nationwide Transmitters

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Transmitter Top Twenty (one)


Which are the most powerful transmitters ?

Just as a bit of fun I compiled this "Top Twenty (one)". The power levels are often different for the PSB MUXES (1 to 3) and the COM MUXES (4 to 6), but I`ve given precedence to the former because far more people watch them, and the programmes on them are (slightly) less likely to be crap, or repeats....                         (also see analogue/digital power equivalence)


Subjects on this page are listed in the following order :


List of transmitters for which we have a dedicated page

MUX names

General transmitter features

Transmitter Relative Heights   including : Time to fall from the top

Top Twenty (one) Transmitters : digital transmission powerwise

Which transmitter am I on ?   (The Digital UK prediction is a start, not a finish)

Coverage maps / reception predictors including : Actual signal levels

Transmitter Radiation Patterns  ( i.e. is it transmitting in your direction ? )

Single Frequency Networks

Problems with your transmitter ?


For information on all the original 80 Digital / Freeview Transmitters

(i.e. the only ones to transmit all 6 MUXES) see Digital Transmitters.

MUX Names

Relative heights of TV transmitters, and the time taken to get a headache after a spanner is dropped from the top. Time for a spanner to fall from the top of TV transmitters, and the speed it reaches......

Note that provided the spanner falls "end on", the speed reduction in air (as opposed to in free space = a vacuum) is not that great, because its surface area is only 0.0001msq. However, when it falls (flat) "side on", and its surface area is 0.0045msq (i.e. 45x greater) the spanners maximum speed in air (its terminal velocity) is only 60mph. At low speeds, when dropped off our shop roof, the drag is relatively insignificant, it`s only at higher speeds that it becomes a major factor.

Whilst John was at it he also worked out the time to fall and the speed at the bottom for Taipei 101 and the Burj Dubai.

John actually went further and calculated the effect that the differing density of the air would have on the velocity reached by the plunging spanner. As can be imagined the varying air density had far more of an effect when falling "flat side on", in fact John reckons said spanner, if dropped off Taipei 101, would actually be travelling slightly quicker (60.5mph) after falling 211m, than it would be when it made a hole in the ground (at 59.5mph) !

Now I`m guessing here, but I reckon anyone who doesn`t find that interesting probably didn`t do Physics at school.....

The “powers that be” keep changing the name of the MUXES, so we just refer to them as MUXES 1 to 6, as they should be anyway....


Don`t you just hate all this name changing b****x ?


Also see : MUXES and PSBs

General Transmitter Features


There are about 1156 * TV transmitters in the UK, and they`re all listed here. Of those 1156 transmitters 50 are “main” transmitters (e.g. Crystal Palace), and 30 are larger repeaters (e.g. Sheffield). Together these make up the 80 original digital transmitters. Incidentally these 80 TXs are the only ones to broadcast all 6 digital MUXES. The remaining transmitters are mainly smaller repeaters (e.g. Oughtibridge) which only transmit the 3 main PSB MUXES, though to be fair that`s most of the channels the majority of people watch.


* source Ofcom Nov 2012 (excludes “self help” transmitters).


Antenna arrays : (main transmitters) at Sudbury and Waltham.


Antenna arrays : (relay/repeater transmitters) Oughtibridge, Birchover and Llanddulas.


Antenna arrays :  Links to manufacturers.


Base of masts : (cylindrical) Belmont, and (spaceframe) Ridge Hill including figures for the weight of masts and details of self supporting towers.


Building a guyed mast : The first 1000ft mast erected in the UK in 1959 (external link)


How high is high ? : Man on a mission at Sandy transmitter.


Feeder cables : Waltham`s feeders (including “duplication”).


Log Periodic Aerials on the repeaters : details of the GD2000.


Mast stays :  They aren`t straight !   The anchor blocks


Number of TV transmitters in the UK : Main and repeater transmitters.


Painting Bilsdale transmitter : “The Bosun`s Chair” system used and details of the type of paint finish used.


Population coverage : Figures for the major transmitters

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Transmitter Relative Heights

               

Just how big would Emley Moor transmitter (TX) look next to Belmont (as originally built) ?

How big would one of the shorter TXs, like The Wrekin, look next to Belmont ?

Just how small would our shop look next to the shortest of the main TXs, The Wrekin ?


We are more than willing to give advice to those actually purchasing from us. Could those only seeking information please just find the answer somewhere on this site, or ring an aerial installer local to them, or call the reception advice phone numbers.

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Which Transmitter Am I On ?


When considering which transmitter to receive your signals from always remember the critical factor is “Line Of Sight”, generally speaking this is far more important than which is the nearest.               (also see Major Transmitters: Which Aerial To Use)


If you`re already on a transmitter and just replacing your aerial then you can identify the transmitter from the frequencies (or channel numbers, note the difference ! ) of the programmes you have tuned in on your TV. The best way is to consult the Channel Allocation Guides (e.g. Crystal Palace) of the transmitters we have a dedicated page for, see list above. Alternatively try this BBC page for analogue frequencies, or, for the digital frequencies, Ofcom pre DSO / post DSO or Digital UK (use the drop down menu to change the region).

Most digiboxes will tell you which transmitter is being received, though in the case of a repeater (e.g. Nottingham) it may just indicate the main transmitter feeding it, in the case of Nottingham it would be Waltham.


If your aerial is vertically polarised it is almost certainly aligned on a repeater transmitter. All but two main transmitters are horizontal (at switchover Rowridge and Rosneath became dual polarity) but bear in mind that some people have incorrectly polarised aerials !

However, not quite 100% of horizontally polarised aerials are on main transmitters, because a few repeaters are horizontally polarised ! ? !


If you`re trying to locate a new transmitter then bear in mind that TV aerials are very directional (particularly if they`re “high gain”) so the simplest way to find out which transmitter you may be on is by checking which way your antenna faces !

Alternatively, at your location, which way do most (or preferably all....) of the other antennas face ? This is a pretty reliable guide but it`s not infallible. We`ve occasionally done installs where every other aerial is utilising a particular transmitter (usually the nearest one......) with imperfect results, we`ve decided to try a different one and it`s come up trumps !


Now check on Transmitter Maps or Main Transmitters map

or MB21`s map page or Ofcom Maps


Bear in mind that they`re hundreds of the smaller repeater / relay transmitters which do not appear on our Digital Nationwide page. If there is more than one transmitter in that particular direction check if the polarity of the aerial(s) gives an indication as to which is the correct one.


You should bear in mind that some transmitters (mainly repeaters) have restricted radiation patterns, see article on transmitter radiation patterns. An example of a restricted transmission pattern was the pre switchover pattern from Sheffield which only broadcast digital at low power to the south so as to avoid co-channel interference with the Totley repeater.

Finding out which transmitters have restricted radiation patterns is very difficult because Ofcom (or “arqiva” (spelt wrong, and I don`t like them anyway) or National Grid Wireless) do not publicise this information. In fact when I managed to talk to Channel Five`s Broadcast Technical Manager he informed me that it was company policy to keep this information confidential !  It`s pathetic, I cannot comprehend why they feel it`s so secret, does the security of the country depend on it ?

Possibly.......

These days it seems that not giving out any information is the “default position”. That said, Ofcom can be more helpful in this regard than any of the others. It`s all a long way from the Public Service ethos that the broadcasters used to adhere to.


Remember that if you are realigning your aerial (to test the signal from a different transmitter), you MUST retune your TV or you won`t get anything at all !

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Transmitter Radiation Patterns


It`s very useful to know if the transmitter you`re thinking of using is actually transmitting full power in your direction. The Digital UK postcode predictor takes this into account, but, as we`ve already discovered, postcode predictors can be rather inaccurate. Now, as already discussed, some of the broadcasters, and Arquiva (sic), are reluctant to tell people what direction the transmitter(s) actually transmit in. However, Brian Butterworth, like a white night on a rampant stallion, used the Freedom of Information act to get some of the radiation patterns released. Unfortunately, as of July 2011 many of the patterns have been withheld, and, worse, many of them are for the bigger transmitters used by the most people (although most main transmitters have Omni directional radiation patterns anyway, e.g. the one for Keelylang Hill). Ofcom told me they really couldn`t think of any reason for the redaction (I hate that word) so the inestimable Brian is trying again. The reply of the 6th March 2012 (from Tom Everest at the BBC) is on the link, and I think their arguments are a load of bollocks. I can`t see why, at the very minimum, transmission patterns for all  the relays (they`re relatively low powered) can`t be released. In my opinion all information should be released unless there`s a bleedin` good reason why not, which there isn`t. here. I hope Brian appeals and wins, there`s a larger principle at stake here......

In the meantime Mike Dimmick was the first to actually convert the data into easily understood patterns, which are listed below by region. On each pattern the top (0 degrees) is North. The further towards the centre the pattern is (in any particular direction) the greater the attenuation of the signal in that direction, if it`s right on the edge of the outer circle that`s full power for that transmitter. However, it`s important to realise that even if the pattern is right towards the middle (i.e showing maximum attenuation) the transmitter will still be giving some signal out, it just means it`ll be harder to pick it up, particularly if the transmitter is one of the lower power relays and/or you`re in a poor signal area.

We are more than willing to give advice to those actually purchasing from us.  

Could those only seeking information please just find the answer somewhere on this site,

or ring an aerial installer local to them. Alternatively call the reception advice

phone numbers (below),  remember, they`re paid to advise you, unlike us.

If it`s a "fault" on your digital, first try retuning your box (or TV).

Retuning help is available here www.tvretune.co.uk

and on telephone number 08546 05 11 22

Alternatively try phoning the supplier where you bought the TV / digibox.


Also see basic fault finding.


Next try Digital UK planned transmitter work, somewhat bizarrely,

but very usefully, this also includes radio transmitters.


The (ex BBC) page for reception problems used to be useful when it listed all

the transmitters experiencing problems, unfortunately in April 2010 it changed

to a post code search type format which is rather less useful/accurate.

The BBC didn`t seem bothered by this, arrogant gits.

But you can always try it if you`re desperate.

This UK Free TV page has the same fault info, but listed by transmitter.


      

Remember that wherever possible transmitters aren`t worked on in the evenings and, particularly, at weekends. So if your signal gets poor all of a sudden check

it`s still poor that night, or over the next weekend, if you can wait....

There is an embargo on transmitter work over Christmas and at other periods

of peak viewing, e.g. when big sporting events are on.

So if the signal goes off half way through the Men`s 100m Olympic final,

it`s unlikely to be (planned) transmitter work.......


Reception advice phone numbers :


03700 100 123  (for BBC)


0344 881 4150  (for ITV)


0345 076 0191  (for C4)


0208 612 7700  (for C5)


(Correct as at October 2014)


For further reading on transmitters see Wikipedia article.


Problems with your signal ?

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Single Frequency Networks (SFNs)


A Single Frequency Network, or SFN, is when a number of transmitters all broadcast the same signal at the same frequency. The best example of this is the DAB network, partly because a lot of car drivers use this service and it`d be annoying, and dangerous, if they had to continually retune their radios as they travelled between areas served by the various transmitters. However there are the odd examples of TV transmitters also using SFNs, the most significant being the group made up of The Wrekin, Bromsgrove and Lark Stoke.


But isn`t co-channel interference one of the big problems for signal reception ?


Well yes it is, but when utilising an SFN the broadcasters get round this by ensuring the same signal is broadcast by all the transmitters and that all the transmitters are locked in phase with each other.


But surely just because the signal is transmitted at the same phase from transmitters that doesn`t necessarily mean it`ll be in phase at all points in any area ?


That`s correct, but the transmissions have a guard interval built into them to enable them to accommodate a certain amount of phase difference. This phase difference is effectively mutipath reception (which manifested itself as "ghosting" with analogue television signals), and so long as the phase difference does not exceed the guard interval all will be well. In addition, the data in the signal is effectively transmitted more than once across the 8MHz width of the transmitted MUX, thus if the signals are out of phase for one frequency, they can`t be out of phase for the other(s).


So if SFNs work why don`t they save loads of frequencies (which they can then sell off) and transmit the 6 television MUXES on the same 6 frequencies all over the country ?


Two reasons.

First there are regional variations in transmissions.

Second there are huge numbers of grouped aerials out there. If A group frequencies were chosen (as used by Crystal Palace for instance) many people with C/D group aerials [e.g.  Winter Hill] wouldn`t pick them up. And vice versa. Having said that, see “CH31 to 37 gap”.


So why doesn`t everyone fit wideband aerials to at least get over the latter problem ?


Well wideband aerials don`t work as well as grouped aerials, particularly for the A group.


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If you`ve found this site informative and, hopefully, interesting as well,

please help us increase the number of people reading it.


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Top Twenty (one) Digital Transmitters.

No aerial installation company would waste their time consulting a coverage map but what they would want access to are the polar diagrams (radiation patterns) of the transmitters and preferably in all three dimensions. It is a pointless waste of time identifying an alternative transmitter (and aligning onto it) if unbeknownst to you the sodding thing is not putting much signal out in your direction ! Unfortunately, for reasons I cannot comprehend, much of this information is not generally available.


Well OK we do provide a link to a site giving “coverage” for all the particular frequencies,

mainly out of interest but also because it can be helpful in identifying possible causes of co-channel interference. Bear in mind that the vast majority of the repeater transmitters aren`t included on this map, e.g. Winter Hill`s repeaters. Use the linked map(s) in conjunction with the Channel Allocation Guides on our transmitter pages.

Just to put the above figures into perspective, post switchover you could put the Emley signal at the test site through a two way splitter (loss 4dB) with each leg feeding an eight way splitter (loss 12dB) which would give 16 points. Including, say, 3dB of cable loss the total loss would be 19dB, and the signal would still  be on the borderline of being excessive !

Even the signals from Belmont (59 miles away) would comfortably feed an eight way splitter.

Down at the shop it`s a rather different story but even there the Emley signal could still feed 4 points if the cable runs weren`t too long, and two points if they were.


And all this is off a relatively low gain DM Log aerial !

Anglia

Borders

Central

Granada

London

Meridian

Scotland (Central)  

Scotland (North)  

Tyne Tees

Ulster

Wales

West (Mendip)

West Country

Yorkshire

When using the links, if necessary,

click on "Show Albums"

(on the left hand side)

Example of a  transmitter radiation pattern

(Oughtibridge transmitter)

Note, due to the new phenomenon of MUXICAL chairs you may experience problems with certain MUXES disappearing. First try rescanning your TV / set top box, do it manually if possible. If this fails to sort it check on transmitter work or call the reception advice phone numbers.


Also see basic digital fault finding.

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List of transmitters for which we have a dedicated page