Small Scale DAB Transmission

Small Scale DAB Transmission
An Innovative solution to a problem
Copyright © Arqiva Limited 2014
Company confidential
1
What are you going to hear about?
Traditional DAB Planning and transmission execution
Smaller Scale DAB Planning – the Challenges
One possible solution
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So, the situation so far…..
ETI
Feed
Transmitter 1
Filter
High Powers
and High
Towers
ETI
Feed 1
ETI
Feed 2
ETI
Feed 3
Transmitter 1
Combiner
and Filtering
Transmitter 2
ACI Filler
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Adjacent Channel Interference, what’s that?
12B
12A
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But, spectrum is scarce……
Orkney &
Shetland
5A
10B
The JPRG plan shows all DAB
10C
10D (could
11B
stay on 11B?)
frequency blocks used multiple
times across the UK
11C
10D
11A
11B
11B
12D
11C
11C
10C
11B
10D
10D
Difficult to see how smaller FM
stations could be accommodated
11C
11D
D1 in England
12D
11B
11B
12A
10C
12C
Isle of Man
12A
10C 12C
12D
10D 10D
10D
10D
11B 12D
12D
11C
12A
10B 12C
12D
10B
11B
11B
12D
11C
12D
12D
10C
10C
11C
12A
10D
12A
10C
11C
11C
12C
10B
12D
11C
11B
London
12A,12C,11B
11C
10C
10D
11C
10C
12D
10B
10B
11B
10D
Channel
Islands
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5
Let’s look at an example
Basingstoke
• Chosen because of its
location close to London and
other multiplex areas.
• Analysis showed that 11C
was the best choice when
considering impact on, and
from, other multiplexes
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The DAB plan for Basingstoke
If planning using “traditional”
route a 1kW ERP DAB
transmitter from the same FM
site would be the most efficient
solution. But this would not be
possible due to the level of
outgoing interference.
The ideal solution would be the
installation of three 30W ERP
(approx.) transmitters.
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How might this proposal be implemented?
What is required:
• Ability to cover small well defined geographic areas
• Probably located in urban / built up centres
• Cost conscious solution
• Easy mitigation of any ACI issues
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So, wouldn’t it be good if we had a one box
solution…..
Multiple
ETI
Feeds
MOD
1-6 DAB
50W
DSP
DAC
RF PA
ʄʃʄ
X
11C
11D
12A
12B
12C
12D
Arqiva have engaged with Affarii Technologies Limited (another
Cambridge Wireless member) to develop such a unit.
10.4 MHz
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….errr but we’ve not quite done it yet !
DAB Modulator
Concept ‘Lash Up’
Existing RF Amplifier
…but it does work….
was needed to simplify
37W RMS - 3CH
fc/19
Signal pre-conditioning
UNLINEARISED
NOISE LIMIT
DPD ACHIEVED
linearity problem.
Required digital correction
bandwidth is 40% of
Carrier Frequency (fc).
Proved to be a harder
problem than a ‘simple’
fc/5
mobile phone basestation.
Advantages
Simpler / cheaper filtering
Easy mitigation of ACI effects
Distribution by EDI (IP) could utilise consumer Broadband?
Ability to add services “at the touch of a button” – potential for DAB
Restricted Service Licences and “Pop Up” stations ?
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Next Steps
Investigating the possibility of a trial licence
Engagement with manufacturers to productise the solution
• One box, sealed unit, no fans
• Engagement with Ofcom to agree Technical Code amendments
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Thank you for listening
Questions?
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