DAB Digital Radio Coverage Area Maps

In June 2011 I was asked if I could provide some simple radiation patterns / polar diagrams for a selection of DAB transmitters in South Wales and parts of South West England. The specific sites were Caradon Hill, Huntshaw Cross, Presely, Carmel, Kilvey Hill and Wenvoe. The information and models presented on this page are purely for interest and none of the predictive plots should be taken as implying that reception will be possible in real circumstances.

Producing the polar diagrams was fairly straightforward since the antenna radiation pattern data is currently readily available from Ofcom. Producing meaningful plots is a little more challenging, so some test plots will be made to compare with known DAB coverage areas.

Transmission providers such as Arqiva use very accurate plotting methods that will accurately predict geographic area and population statistics for both indoor and mobile reception. Bear in mind that the plots presented here are for a single transmitter and do not take into account the effects of noise and interference nor the fact that the transmitter will be part of a Single Frequency Network. An SFN used for digital radio helps reinforce signals by using multiple transmitter sites all using the same frequency (Unlike analogue radio networks which must use discrete and carefully planned frequencies to avoid mutual co-channel interference). Our methods are very much simpler and also have a lower pixel reolution, but even so can still give a good idea as to the area where reception can be expected. Therefore where the plot indicates that the signals is weak from that specific transmitter site, one of the other transmitters in the SFN may very well provide a stronger and perfectly usable signal - which is the whole idea of SFN's.

The thresholds for plotting DAB areas is usually taken as a field strength contour of 57dBuV/m (mauve) for indoor reception and 50dBuV/m (or sometimes 48 dBuV/m) for mobile use (blue). Each case assumes that the receiving antenna sited 1.5m above ground level. For pocket radios a field strength of 64dBuV/m is used fwhich takes into account their smaller less efficient antennas and challenging conditions of use.

Transmitter Site / DAB Multiplex Ensemble Name	Power (Kw)	Antenna Height Metres a.g.l.	Antenna Pattern (from Ofcom Data)	Multiplex Block	Frequency (MHz)	N.G.R.	Link to polar diagram or plot
Caradon Hill:
BBC National DAB	2.5	153m	Omni	12B	225.648	SX273707	view pattern
D1 National DAB	2.0	203m	345°	11D	222.064	SX273707	view pattern
Cornwall local DAB	1.58	203m	345°	11B	218.640	SX273707	view pattern

Carmel:
BBC National DAB	3.0	140m	Omni	12B	225.648	SN576153	view pattern
D1 National DAB	1.0	142m	110°	11D	222.064	SN576153	view pattern
Severn Estuary Regional DAB	0.5	142m	110°	12C	227.360	SN576153	view pattern
Swansea & South West Wales DAB	1.0	142m	110°	12A	223.936	SN576153	view pattern

Huntshaw Cross:
BBC National DAB	2.5	131m	90°	12B	225.648	SS527220	view pattern
D1 National DAB	4.0	114m	350°	11D	222.064	SS527220	view pattern

Kilvey Hill:
BBC National DAB	3.0	45m	70°	12B	225.648	SS672940	view pattern
D1 National DAB	1.0	45m	70°	11D	222.064	SS672940	view pattern
Severn Estuary Regional DAB	0.5	45m	70°	12C	227.360	SS672940	view pattern
Swansea & South West Wales DAB	2.0	45m	70°	12A	223.936	SS672940	view plot

Presely / Preselii:
BBC National DAB	5.0	207m	110°	12B	225.648	SN172306	view pattern
D1 National DAB	1.0	207m	110°	11D	222.064	SN172306	view pattern

The Wrekin:
BBC National DAB	5.0	45m	Omni + / - 5dB	12B	225.648	SJ628082	view pattern
D1 National DAB	8.0	45m	Omni + / - 5dB	11D	222.064	SJ628082	view pattern
West Midlands Regional DAB	4.0	40m	170°	12A	223.936	SJ628082	view pattern
W'ton & Shropshire Local DAB	0.5	43m	180°	11B	218.64	SJ628082	view pattern

Wenvoe:
BBC National DAB	8.0	200m	340°	12B	225.648	ST110742	view pattern
D1 National DAB	4.0	200m	340°	11D	222.064	ST110742	view pattern
Severn Estuary Regional DAB	4.0	140m	40°	12C	227.360	ST110742	view pattern

Below are the antenna polar diagrams for the above transmitters. A selection of estimated coverage areas for specific transmitter will follow in due course.

CARADON HILL

BBC National DAB: