new international digital audio-broadcasting standard ... · new international digital...

TECHNOLOGIES RADIO & SIGNAL UNIT 1

THALES COMMUNICATIONS

New InternationalDigital audio-broadcastingstandard, voice coding and amateur radio applications

Cédric DEMEURE

Hamvention, Dayton, Ohio, USAMay 19 2002



Summary

Digital Radio Mondiale

HF High data rate Modem

Speech coders

Digital Amateur Radio 3 kHz demonstrator



DRMWorld-wide consortium to promote a unique standard for digital LF, MF & HF audio-broadcasting

Members include :Broadcasters and Broadcasting associationsNetwork OperatorsResearch InstitutesComponent, Receiver and Transmitter ManufacturersRegulatory and Standardisation Authorities

Key features:Worldwide standard Better audio quality Simple to use receiversLow cost equipment Text message Data applicationsProvide future enhancements



DRM

73 DRM-Members from 27 countries, Feb 2002



DRM Members

See www.drm.org for more details

USAHarris BroadcastInternational Broadcasting Bureau Continental Electronics CorporationSangean America Inc.Technology for Communications International

Others :BBC, Sony, Bosch, Thales, NHK, RFI, DW, JVC, Telefunken ...



ETSI

DRM STANDARDISATION PROCESS

ARIB

DRM

ITU

ISOMPEG

National delegation

IEC

JRG ITU/IEC

ITUSector

member

Other regionalstandardisation bodies



DRM: Different transmission modes (1)System flexibility in Digital

4.5 kHz Carrier Groupcontaining FAC cells

4.5 kHz additionalGroup of Carriers

4.5 kHz

9 kHz

18 kHz

Frequency

Spectrum occupancyfor 4.5 kHz channeling

5 kHz Carrier Groupcontaining FAC cells

5 kHz additionalGroup of Carriers

5 kHz

10 kHz

20 kHz

for 5 kHz channeling

FAC: Fast Access Channel



DRM: Different transmission modes (2)System flexibility in Simulcast

AM DSB signal

AM VSB signal

Group of carriers containing FAC cells

Group of carriers

Additionalpossibilitiesin HF bands

only

All bands



DRM ModemA highly efficient and flexible OFDM modem:

very high spectrum efficiency: up to 3 bit/Hz/smulti-modes related to propagation and channel bandwidthOFDM preferred over single carrier because of flexibility

Various transmission modes adapted to different Propagation types

Mode A: Gaussian channels, with minor fading LW and MW during daytime

Mode B: Time and frequency selective channels, with longer delay spread: SW and MW nighttime

Mode C: Time and frequency selective channels, with greaterdoppler spread: bad SW channels

Mode D : Very robust mode



DRM Modem (3)

Frequency Reference

Time Reference

Gain Reference

Remote Control

Useful Symbol15

50

75

10

20

30

40

50

60

70

80

90

100

110

-20

-10

-30

120

130

-40

1.5 kHz

3 kHz

1.5 kHz

DCcomponent

33 1/3 Hz

Frame: 8 OFDM Symbols, 288 msSymbol: 30 ms Useful Symbol + 6 ms Guard Interval

0

(old version)



System architecture: TX side

SDC (ServiceDescription Channel)

FAC (FastAccess Channel)

DataStream

AudioSignal

DRMTransmission

Signal

Normal Protection

HighProtection

EnergyDispersal

EnergyDispersal

Cha

nnel

Enco

der

OFDMSignal

Generator

Mod

ulat

or

OFD

M C

ell M

appe

r

MSC

PilotGenerator

EnergyDispersal

FAC

AACStereo

AACMono

NarrowBandCELP

NarrowBandCELP

EnergyDispersal

SDC

Mul

tiple

x

SpectralBand

ReplicationSBR

Higher bit-ratemax: 48 kbit/s

Pre-coder

Pre-coder

Pre-coderNormal Protection

High Protection

ChannelEncoder

ChannelEncoder

AudioSuper

Framing

Standard Mode

20 kbit/s

UltraRobustMode

10 kbit/s

Low bitrate Mode

8 kbit/s

CellInterleaver



DRM Experimental System HardwareGeneral functional block Diagram



DRM Experimental system

MMI transmit MMI receive

Modem Analysis tool Propagation Analysis tool



System Validation : tests

MW Validation:- 1 transmmission site

- 5 receiving sites

Large investigation : most critical paths validated

SW Validation:- 5 transmmission sites and 17 receiving sites

- All SW frequency bands: 5MHz to 25 MHz



Compatibility with existing AM Services

Spectrum at distant receiving site

with Analogue AM DSB signal

with Digital DRM signal

Non-modified250 kW PSM SW TX Output Spectrum

at 80 kW rmsdigital output power



DRM Status: receiver chipset & Standard

Various projects to develop chip-sets

Eureka (European Commission sponsored program) DIAM:Atmel, Bosch, Sony, TDF, Thales ...2 chips (1 analog RF, 1 digital), direct conversion receiverForecast Availability: end 2003

DRM the only worldwide ITU standard at SW DRM and IBOC ITU standard at LW and MWIBOC standard at FM

Work proposed to extend DRM to FM bands



Voice coders: Standards and Performances

Bit rate (bits/s)1k 2k 4k 8k 16k 32k 64k

IndicativeQuality (MOS)

1

2

3

4

5G711(72)

G726(88)

ST4209(83)

G 728(92)

FS 1016(90)

G 729(96)

ST 4479(93)

ST 4198(87)

STG 4591MELP (02)

LPC 10(83)

GSM(87)

G 723-1CELP (96)

HSX(96)

Waveform codersParametric coders Hybrid coders

WBLBR

VLBR

Research codersExisting products



Voice coders: quality

1

2

3

4

5

1980 1990 2000

IndicativeQuality (MOS)

G.711(64 kb/s) G.721

(32 kb/s) G.729(8 kb/s)

G.728(16 kb/s)

STG 4198LPC (2,4 kb/s)

STG4591 (2,4 kb/s1.2 kb/s)

Consumer quality

Minimum qual.for high cost application

Minimum qual.For low cost application

1970

G.xxx(4 kb/s)

HSX(2,4 kb/s)

2010



Other low rate voice coders

ITU 4 kbits/s : no selection yet between the various proponents

DVSI : proprietary format (IMBE and AMBE: 2 to 9.6 kbits/s) mainly chosen for satellite communications systems (Inmarsat), Iridium and APCO 25

Texas MELP : basis for the STG 4591 Stanag

Except for ITU 4kbits/s, all have rather high processing delay implying long PTT return time



Amateur Radio Demonstrator

Adaptation of the DRM reference receiver for 3 kHz channels

Push-to-talk

Various modes according to :Voice coder rate : 1200, 2400, 3200 bits/s (4000-4800 pending)Modem robustnessChoice will be made during lab and fields experiments

100% PC based for simple integrationFull demonstrator working with Ten-Tec and Kenwood off-the-self transceiversAcross the Atlantic tests planned for 2002 with ARRL



MMIin transmit

mode



MMIin receive

mode



CONCLUSIONS

DRM World-wide standard is a good technology basisfor Ham

Narrow band, PTT mode easily derived for HF Ham use

Available low bit rate vocoder quality reached acceptable quality

ARRL plans lab tests then trans-atlantic tests in 2002



Thank you for your attention

Questions ??



Australia: FARBChina: Academy of Broadcasting ScienceCanada: Radio Canada International, Nautel LtdCzech R. HFCCCroatia RIZEgypt: Egyptian Radio and Television UnionEcuador: ESPOL, HCJBFrance: Atmel, CCETT, Europe 1, Radio France, Radio France Int., TDF, ThalesFinland: Kymenlaakso PolytechnicGermany: APR, Digitalrundfunk Sachsen Anhalt, DLM, DTAG, DW, DLR, FHG, IRT, Micronas, Robert

Bosch, Sony Intern., SWR, Telefunken Sendertechnik,, U. of Hanover, U. of Merseburg, U. of Ulm, VPRT

Hungary: Communication Authority, Antenna HungariaIndia: All India RadioItaly: RAIJapan: Hitachi Kokusai, JVC, NHKLuxembourg Broadcasting Centre Europe (RTL-CTL)Malaysia: ABUNetherlands: Nozema, Radio Nederland WereldomroepNigeria: Voice Of NigeriaNorway: TelenorNew Zealand: Radio NZ Int.Russia: Main Centre for Control of Broadcasting Networks and the Voice of RussiaSpain: Retevision, Universidad del Pais VascoSweden: Coding Technologies, Radio Sweden Int., TERACOM SE, Factum Electronics ABSwitzerland: EBU, ITU, ICRCTunesia: Arab State Broadcasting UnionUK: BBC, Christian Vision, LSI Logic, Merlin Com. Int., Qinetiq Ltd, Roke Manor Research Ltd.,

RadioScapeUSA: Continental Electronics Corp., Harris Corp., Sangean America, TCI, IBB/VOA, NASB



DIAM ChipsetR

F An

alog

ueFr

ont-E

nd

DDC1

Switch Matrix

DDC2FM input

AM input

RF Digital Front-End

InitialSynchro

SymbolsDemodulation

Narrow-band jammerrejection

MLC decoder: control part(SW)

Demux

Audiodecoders

MMI anddata services

MLC decoder:Viterbi decodingprocessor (HW)

Audiooutput

Audiointerface

Hostprocessor

USB (or other)interface

Ext. datamem.

Ext. datamem.

Ext. prog.mem.

Internalcontrols and

configurations

8 Mbit SRAM

4 Mbit SRAM

8 Mbit SRAM

2 Mbit Flash

I-Cache8 kbytes

Ext. prog.mem.

2 Mbit Flash

DMA

AHB

APB bridgeAPB bus

D-Cache8 kbytes

D-TCM64 kbytes

I-TCM32 kbytes

ANALOGCHIP

DIGITAL CHIP



Demonstrator Description

Can transmit at the same time vocoded voice + data(text message, text files, image files...)

available HSX vocoders : 1200 b/s, 2400 b/s, 3200 b/s(easy addition of other vocoders)

Can receive both DRM and SSBSSB : audio ouput is the SSB audioDRM : audio output is the vocoder output. In this case, also displays frame error rate, frequency offset, estimated SNR, estimated channel impulseresponse (in 3D representation)

3 degrees of protection :GND (Ground-wave) for short distance communicationSKY (Sky Wave) for long distanceROB (Robust) for difficult conditions

Choice between short and long interleaving



Demonstrator Main Features

A simple hardware interfacing system with Radio-Amateur transceivers

levels adaptationsPush-To-Talk detectionan adjustable VOX systemreceiving level monitoring (if available)

Easy personalisationone editable text file defines the preferred starting optionsone additional editable text file (Settings.cmd) allows adjusting other parameters (thresholds, gains, squelch level...)



Other features

Automatic re-programming of the receiver according to thecurrently received messageIntegrated auto-testSophisticated channel simulator (for checking performances in terms of SNR, frequency offset, channel severity)PTT testMonitoring level testTransmission of a pure tone instead of the DRM signalLocal vocoder auto-test

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