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.
Click for transmitters
Which Freeview channels does the Bressay transmitter broadcast?
Which Freeview channels does the Whitehawk Hill transmitter broadcast?
Which Freeview channels does the Winter Hill transmitter broadcast?
Which Freeview channels does the Huntshaw Cross transmitter broadcast?
Which Freeview channels does the Guildford transmitter broadcast?
Which Freeview channels does the Divis transmitter broadcast?
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5:30 PM
The Sudbury transmitter appears to be having a Freeview problem on channel 47 and HD programmes are not available even after retuning. Any info, please?
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7:28 AM
I'm a new boy, so please bear with me when I might be asking the obvious...
I see that there is a 'new' transmitter coming soon for Driffield, East Yorkshire. Does anyone know when is 'soon'?
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11:43 AM
Norwich
Martyn Johnson: Hi, Martin. There doesn't appear to be any new transmitter specifically for Driffield, whether for Freeview TV or for DAB digital radio. Where did you get this info from and when did you think the Driffield transmitter was going to go live? Richard, Norwich (June 2016).
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Richard's: mapR's Freeview map terrainR's terrain plot wavesR's frequency data R's Freeview Detailed Coverage
1:19 PM
I live in SE Cornwall and usually enjoy excellent Freeview from the Redruth transmitter. In the past week or so there has been much interruption to the sound and some pixillation ...... I was under the impression that those problems should have gone a long time ago? Is there a reason for this change?
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3:22 PM
David Watters: There has been no recent engineering work at Redruth in the last couple of weeks so nothing to suggest that anything has changed at the transmitter. Suggest you check out your own aerial system, start at the back of the TV and check all cables and connections then work your way back as far as you can safely access towards the aerial.
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12:53 PM
My signal is supplied by the Durris Transmitter. Every morning at 01.10am the signal drops, it is not a fault with the TV but it is a signalling problem. Can someone advise why this is happening and how to fix it?
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2:07 PM
Rachel Law:
Check for local sources of interference, such as time switches. Also check with your neighbours whether they have the same problem and whether they have a time switch set to operate at that time. Do you have a switch set at that time?
There is no known fault with the transmitter else thousands of people would have the same problem.
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I live in the town of Midhurst but cannot receive Com 7 channels from the Midhurst transmitter (i.e. BBC4 HD). Do you think re-tuning to the Hannington transmitter would work? And would our aerial direction have to be changed?
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11:06 PM
Joe Vitagliano : A quick look at the coverage map for Hannington would suggest that you're too far away, but if you provide a postcode we can get a more accurate prediction for available transmitters and signal strengths at your location.
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