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New and improved Freeview radiation patterns

I'm very pleased to announce that the list of the radiation patterns - the diagrams that show the power levels for each direction from a transmitter - have returned in an improved format. In addition UK Free TV now has 528 new patterns received in the last month from Ofcom under a Freedom of Information Act request.

Radiation patterns   Photograph: pssl.com
Radiation patterns Photograph: pssl.com
published on UK Free TV

What are radiation patterns?

All ground-based broadcast transmitter – be it for a Freeview, DAB, AM/FM radio or mobile phones – can and do broadcast their output at different levels in different directions.

The diagrams here on UK Free TV show all the known patterns.   In theory each transmitter can have a different pattern for each transmission frequency.     

This diagram shows how the Primrose Hill Freeview transmitter's coverage map and the radiation pattern for it.

Radiation pattern example

Why did you say "known patterns"?

Because, and I quote

  • disclosure of the antenna radiation patterns into the public domain could lead to these being available to foreign administrations, which would substantially weaken HM Government's negotiating position with respect to international frequency clearance;
  • a weaker negotiating position for HM Government may lead to additional cost for the broadcasters (where antenna systems have to be re-built as a result of international coordination) and lower coverage for viewers (where antenna systems have to be restricted in order to protect foreign transmissions); and
  • the BBC is required to provide coverage of its services on digital terrestrial television to a certain proportion of the population by the completion of switchover and a failure or suboptimal result from international co-ordination may harm the BBC's ability to meet this obligation.

The number of sites that we have data is limited to the data released by the BBC in 2009 – see Update on transmitter radiation patterns (BBC FOI request) – plus the new data from Ofcom.

 

What is the new data?

With help from Dave Lindsay, I contacted Ofcom to ask them to release the data related to the upcoming UK Digital Terrestrial Television: International Coordination Agreements

I do note that on the above-mentioned Ofcom link there is a link to "International Co-ordination Technical Parameters and Nominal Antenna Templates"  http://www.ofcom.org.uk/static/broadcasting/Web_Int%20Coord%20800MHz%20DTT%20Clr%20Tech%20and%20Nominal%20Templates_22May13.pdf  This would appear, on the surface, to provide some of the missing transmitter data.     Whilst I understand that this is co-ordination information and may represent greater coverage than the actual transmitters use, I would prefer to have some radiation pattern information with a written warning, rather than "none".  

Do the new patterns match the output?

"While you are already aware of this, I would like to emphasise that the powers and antenna templates in these files represent the upper limit of the UK’s internationally agreed rights for specific frequency assignments, and the actual antenna patterns and/or powers used by the broadcasters are often more restricted. Additionally, not all of the assignments which have been co-ordinated are currently in use." - Ofcom

 

New SVG format

UK Free TV was using "HTML5 canvas" to draw the radiation patterns.     However the site now uses the SVG format for the graphics.     This has the several advantages, in particular that it is now easy to embed more than one diagram in a page where necessary. 

 

Some examples of the new data

Where the diagrams show (CCN) this is the new "Co-ordination combined nominal template derived from International co-ordination technical agreements" data.  A pattern with a "F" prefix is for a frequency not currently used at that mast for a live TV service (F570 is 570MHz also known as UHF C33). 

New radition patterns

 

What next?

The site's coverage maps will be regenerated soon to include all this new data. 

 



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Comments
Tuesday, 19 May 2020
M
megan tann
12:00 PM

Hi. Should we keep getting no signal for various channels at very random times..sometimes in rain and some in perfect weather?

link to this comment
megan tann's 1 post GB
C
Chris.SE
sentiment_satisfiedGold

1:44 PM

megan tann:

There could be a multitude of reasons for that from problems with your aerial system, downlead, connections etc. to transmitter maintenance - a lot of transmitters currently have Planned Engineering - or you may not be in a particularly good reception area for some multiplexes.

To be able to give some constructive help, we need a full postcode to see what the Freeview Predicted Coverage Checker is giving for predicted reception at your locale, and a bit more precise information about which channels you especially have problems with.

link to this comment
Chris.SE's 1,840 posts GB
Saturday, 29 August 2020
B
Brian Addison
8:05 AM

Came back from holiday in August to find I had to re-tune Freeview. After that all channels have a weak signal and at times lose the picture - tried TV nearest the aerial but same problem. What has happened to the Sudbury transmitter that I cannot watch any Freeview channel reduced to Broadband TV now.

link to this comment
Brian Addison's 1 post GB
S
StevensOnln1
sentiment_very_satisfiedPlatinum

11:46 AM

Brian Addison: There have been no recent changes at Sudbury, the only recent frequency changes have been in the north of England. Have you checked for any loose or damaged cables or connections behind each TV? As you have multiple TVs, have you checked the splitter or amplifier that distributes the signal from the aerial? It may be that something has been damaged by the recent bad weather. If you provide a full postcode we can check what your predicted signal strength is and whether you may have inadvertently picked up a weaker signal from a different transmitter when you retuned.

link to this comment
StevensOnln1's 2,920 posts GB
Sunday, 13 September 2020
J
John O`
12:00 PM

Is any work being carried out on the Aughrim TV transmitter near Kilkeel in Northern Ireland?

link to this comment
John O`'s 1 post GB
Monday, 14 September 2020
C
Chris.SE
sentiment_satisfiedGold

5:10 AM

John O`:

The Kilkeel transmitter is currently listed for Planned Engineering.

link to this comment
Chris.SE's 1,840 posts GB
Sunday, 27 September 2020
R
Ron Potter
6:08 PM

Question about the Ardintoul Mast. IV408JG.

is there any possibility of supplying Internet Access (only locally ) via a wifi hotspot of some description ?

Please advise ?

Regards Ron

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Ron Potter's 1 post GB
C
Chris.SE
sentiment_satisfiedGold

10:16 PM

Ron Potter:

Not sure what the purpose of your question is! Internet Access for you or the transmitter, to what point?
We wouldn't know if there were any local wifi hotspots.

The Ardintoul transmitter is currently listed for Planned Engineering with "Possible service interruptions". If you retuned at all when you had no signal (not normally advised), it will likely have just cleared the correct tuning and you'll have to repeat the retune when signals are normal. You may have to try several times.

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Chris.SE's 1,840 posts GB
Tuesday, 17 November 2020
M
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