New and improved Freeview radiation patterns
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.
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
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).
What next?
The site's coverage maps will be regenerated soon to include all this new data.
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.
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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.
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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.
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12:00 PM
Is any work being carried out on the Aughrim TV transmitter near Kilkeel in Northern Ireland?
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5:10 AM
John O`:
The Kilkeel transmitter is currently listed for Planned Engineering.
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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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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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I do agree with all the ideas you've introduced in your post.
They are very convincing and can certainly work. Still,
the posts are very quick for starters. May you please prolong
them a little from subsequent time? Thank you for the post.
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4:17 PM
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Everything is very open with a really clear description of
the issues. It was truly informative. Your site is extremely helpful.
Many thanks for sharing!
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