Small scale DAB technical event

13 November 2014

Agenda

• Presentation 09.30 – 10.00 13.00 – 13.30

– Technical development so far

– Trial licensing

• Demonstrations 10.00 – 12.00 13.30 – 15.30

– Single transmitter

– Satellite gap filler

– On-channel repeater

• Q&A session 12.00 – 12.30 15.30 – 16.00

• Lunch 12.30 – 13.00 12.30 – 13.00

• Tour of Baldock facilities (optional)

• Coach departs for Baldock station 13.00 16.30

1

Morning session Afternoon session

Introduction

Peter Madry

Principal, Spectrum Policy Group

2

Small-scale DAB: the story so far

3

• The existing DAB platform is not well-suited for carrying smaller radio

services, primarily because of the cost and the coverage.

• The Brighton trial suggested there may be another way of doing things which

could work well for small stations.

• The Government is so interested in this it is giving us money to explore

further.

• This event is an opportunity for us to explain the progress made since

Brighton and to demonstrate some of the technical infrastructure in use.

What is the objective?

• The work we intend to do over the next two years has two main objectives:

– To further test the practicality of implementing the approach used in the

Brighton trial.

– To design an appropriate licensing framework which would enable small-

scale DAB services to broadcast.

• We believe that any ‘solutions’ should be:

– simple

– cost-effective

– flexible

4

Technical development so far

5

Analogue vs Digital – what’s the difference?

• Analogue

– Provides one service per channel, and set of infrastructure

– Graceful fade

– Universal quality

– Simple transmission chain

• Digital

– Typically provides multiple services (with mostly uniform coverage)

– Digital cliff

– Quality tailoring between services

– More complex transmission chain

6

Traditional DAB transmission chain

7

Audio ISO Encoders

(One for each service)

Ensemble Multiplexer

COFDM Modulator

RF Linear Amplifier

Spectrum Mask Filter

Not economical for small areas!

E1 Leased Lines

Low cost approach

8

Audio ISO Encoders,

Multiplexer and

Modulator on single PC

Software Defined Radio

RF Linear Amplifier

Simpler filtering?

Typical transmitter architecture

9

Mask filter Power

amplifier

Software

defined radio Multiplexer &

modulator

Sound programme service 1

provider Transmitting

antenna

Feeder

cable Distribution

(internet)

Transmitter site

Encoder

Encoder

Sound programme service 2

provider

Audio

Audio

Developments since Brighton trial

Encoder Multiplexer Modulator

TooLAME-DAB ODR-DabMux ODR-DabMod

MPEG 1 Layer 2 audio encoder DAB multiplexer EN 300 401 compliant modulator

Achieved:

• Professional sound server

input

• ARM support

• Improved configuration file

support

• Time stamping for SFN

operation

• MP2 input and ETI output

than can operate with

encoder and modulator

• Remote control for

setting/getting parameters

• Improved configuration file

support

• Time stamping for SFN

operation

• Improvements in logging

• FIR filter

• Remote control

• Running on Odroid U3

(Galaxy S3 ARM phone chip)

To be done:

• Test DLS and Slideshow

• Configuration ‘app’ to make

setup easier

• Experimental EDI output

• Configuration ‘app’ to make

setup easier

• Experimental EDI output

10

Technical work we plan to do

• Frequency planning

• Single frequency network operation

• Further software development

• Field testing

11

What you’ll see today

12

Mask filter Power

amplifier

Software

defined radio

Encoding,

multiplexing

& modulator

Transmitting

antenna

Feeder

cable

Single

transmitter

Audio x n

Mask filter On-channel

repeater

Transmitting

antenna

Feeder

cable

On-channel

repeater

Off-air signal

Satellite fed

gap filler

Mask filter

Power

amplifier

Software

defined radio

Odroid

Satellite

receiver

Trial licensing

13

Consultation proposals

• Three trials:

– Single transmitter

– Two transmitter SFN

– Two transmitter SFN with one an

on-channel repeater

• Applicants need to identify suitable

transmission sites and at least one

other service provider to be carried in

their trial multiplex

• Ofcom can provide equipment,

although licensees will be able to use

their own

14

Next steps

• Consultation on small scale DAB trial licensing closes 10 December

• We plan to publish a statement and invite applications during Q1 of 2015

• Trials would run from mid-2015 to March 2016

• Separately, we are giving further thought to a licensing framework

15

Questions?

16