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DAB maps - another update

Just another look at how the DAB mapping is coming on

published on UK Free TV

Just a quick update to show a more advanced version of the DAB transmitter map for Kilvey Hill.


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Wednesday, 8 June 2011
Chris Heard
2:04 PM

A great start, and thanks in advance.

It'll clearly demonstrate often the fininacial contrainsts and power restrictions used by commercial operators compared with the BBC.

Obviously a bit of local terrain knowledge will still be necessary, but the indication of the target area should help - especially when trying to seperate coverage areas of a SFN.

Hopefully it'll confirm my assumptions about the Redruth southerly retricted radiation. Much easier to read than scrolling through the Ofcom spreadsheet!

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Chris Heard's 4 posts GB

4:10 PM

Chris Heard: I'm not planning on using any terrain information for the DAB transmitters, as the signals do travel over the horizon more than is useful for television.

Most of the restrictions are due to the nature of SFN, as each area should only be served by one transmitter. When a new DAB transmitter is introduced, restrictions are placed on one or more of the rest to compensate.

I will post Redruth up next time I do an update.

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Briantist's 38,844 posts GB
Thursday, 9 June 2011

9:14 AM

KILVEY HILL DAB - Strange that this map suggests that immediately adjacent Swansea itself is not included in the target area.
There would be some signal off the back of the array, of course. The indicated KH area would presumably be reached by Preseli, given the more "bendy" propagation at 225 MHz. Does Wenvoe or Carmel specifically target Swansea?

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michael's 857 posts GB

1:37 PM

michael: The Ofcom radiation patterns are:

11D: 2,1,1,1,0,0,0,0,0,0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7,6,5,5,5,6,6,5,5,3,2,2

12A: 2,1.5,1.25,0.75,0.5,0.25,0,0,0,0.25,0.5,1,1.5,2,2.5,3,3.5,4,4.25,4.5,5,5.75,6.75,7.5,7,6.5,5.5,5.25,5.5,6,6,5,4.25,3.25,2.5,2.25

12C: 2,1.5,1.25,0.75,0.5,0.25,0,0,0,0.25,0.5,1,1.5,2,2.5,3,3.5,4,4.25,4.5,5,5.75,6.75,7.5,7,6.5,5.5,5.25,5.5,6,6,5,4.25,3.25,2.5,2.25

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Briantist's 38,844 posts GB
Chris Heard
1:38 PM

Briantist: I certainly wasn't suggesting you work out the terrain for the calculations as well, just for us readers to consider if there's indiscrepancies from what we find on the ground.

Interesting note on the restrictions. The industry seems to herald the robustness of having multiple transmitters covering one point.

Re: Redruth, I was surprised how quickly the signal disappeared when terrain shouldn't have been an issue to the south. Thankfully the new-ish Helston tx more than substitutes, and as you said proves the signal extends well over the horizon/line of sight to reach the Lizard point.

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Chris Heard's 4 posts GB
Friday, 10 June 2011

8:11 AM

Chris Heard: DAB, as a single frequency network, requires that ONLY one transmitter covers each point.

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Briantist's 38,844 posts GB
Jm F

12:33 PM

Briantist: Not sure how you've drawn those HRP patterns - if I use the same Ofcom data for 12A (as you've listed above) I get a much "rounder" pattern without those sharp corners.
How has the range (radius) for each pattern been determined?

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Jm F's 141 posts GB

8:44 PM

Briantist, DAB can have multiple transmitters covering the same area - that's the whole point of it being an SFN.

As long as the transmitters are all synchronised by GPS then all is well.

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Ash's 27 posts GB

10:11 PM

By the way... Digital One and NOW Digital do publish coverage maps on their websites.

ukdigitalradio: Coverage



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Ash's 27 posts GB
Saturday, 11 June 2011
9:57 AM

Even though SFNs, in away, hide many needs for coverage area consideration by many users it is still a very important asset in certain topographical locations - like mine! Soma maps I have seen suggest that Hastings Tx would just serve this location, but its actually behind/underneath a hill. So I guess coverage of Heathfield Tx is important to see mapped - about 20 years ago it was just possible to see the top mounted ANL, after dark on very clear nights. But DAB reception is not great here presumably the Heathfield Tx field strength is terrain limited at this location?

For these sort of reasons, I believe the pixel display is more useful than the "coverage area" display, because they show the small areas in shadow which do not show in area displays.

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Bev MARKS's 2 posts GB
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