Digital Radio Mondiale technical and market progression Australia and International

1
Digital Radio Mondialetechnical and market
progression Australia and International

• by TJH Systems Pty Ltdpresented byTrevor
  HarwoodGlen EnglishDecember 2006

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Basic overview of DRM

• Developed in Europe
• MF-HF Specification matured as a standard approx
  2 years ago.
• Designed for noisy, time dispersive channels
  with low SNR
• Uses COFDM modulation like DVBT and DAB
• Ideal for MF services up to 300km
• Ideal for HF/ SW Vertical Incidence and
  international service

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DRM overview

• Occupied bandwidth 4.5 to 20 kHz which is
  designed to fit in existing MF and HF planning
• Data pipe from 7 to 65kbps depending on
  robustness and bandwidth
• Typical for 9 kHz allocation is 23.6kbps.
• MPEG4 AAC-HE and low bit rate speech codecs
  supported

4
Broadcaster advantages

• Audio signal to noise and frequency response
  improved compared to current analog MF and HF
  broadcasting
• Can carry multiple programs at different
  qualities in the one stream.
• Program information low data rate channel
• Multipath distortion that limits existing
  coverage improves nighttime service and extends
  fringe

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Advantages cont...

• Supports SFN- Single frequency networking
  efficient spectral re-use
• Power levels, equipment types, antenna technology
  are similar to existing infrastructure
• Network broadcasters will have consistency across
  their network.

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Radio Market

• Convergence is the buzzword
• Mature , established digital radio technologies
  such at DAB, DMB-T provide interactivity, low
  resolution video, data facilities .
• DVB-H is a data pipe platform optimised for
  mobile delivery in the UHF bands and can provide
  DMB-Ts facilities and more.
• Commercial radio feels the need to keep up with
  competition from multimedia mobile phone services
  and personal audio players.

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Digital downsides

• But this additional multimedia comes at a
  price-- robustness
• Insufficient signal (excessive BER) has a
  catastrophic effect on program.
• Users are used to analog style degradation, and
  will put up with the odd bit of noise and
  distortion from time to time
• Digital services- nothing graceful about their
  degradation- dropouts are abrupt and it often
  takes time to re-synchronize.

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Audience retraining ?

• Audiences will not tolerate a new medium that
  has such interruptions and behaviour this will
  influence its success.
• Audiences cannot easily find a good spot amongst
  bad spots for their receiver
• The better the digital system, the more abrupt
  the location variability near the threshold.

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Big signals required...

• This abrupt dropout effect generates a very high
  reliability requirement and is a headache for
  planners and operators
• Engineers are only recently developing techniques
  for combating in-building and high local
  multipath environments
• Mature digital radio technologies such as DAB and
  DMB-T are sub-optimal compared to recently
  developed technologies

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No need to discard DAB related technologies though

• Good receiver base
• Much experience in the UK with regards to
  requirements and quality of coverage.
• High field strengths developed by high power
  and/or multiple transmitters can successfully
  fix these defficiencies for mature technologies.
• Generating high field strengths to replicate
  existing analog coverage unlikely to be practical
  for rural and wide area services.

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Analog Robustness success

• Existing analog radio is robust
• Listeners tolerate a little noise, distortion.
• The majority of the current audience just want
  reliable reception everywhere they have it now.
• Radio has been successful because the audience
  listen when they are doing something else, or
  with their eyes shut.
• Radio success is also its content which the
  quality must be held to hold its success.

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DAB/DMB-T have been successful in Europe, but

• Australia does not have the population density of
  the European markets
• In Europe, broadcasters choose not to cover
  dispersed population centres as it is impractical
  and uneconomical to generate the high field
  strengths.
• Australias ABC MF services provide blanket
  coverage over large areas with little
  infrastructure.
• DAB / DMB-T provide an excellent service in well
  populated cities- but regional application will
  leave many without a service.

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US IBOC Systems

• United States has developed their own HD named
  digital system
• Uses same spectrum as existing FM services.
• Provides 100kbps multiple program MPEG4 audio
  pipe
• Supports SFN
• Mitigates dropouts with fade back to analog.

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US IBOC Systems

• gt800 stations on air
• FM HD system provides excellent coverage with
  full digital upgrade path.
• AM HD system uses adjacent channel.
• Not successful at this time as nighttime
  propagation prevents the adjacent channel
  operation.

15
DRM technologies

• MF- DRM useful for duplicating and improving
  local and wide area AM services
• HF DRM a superior solution to AM or SSB for
  vertical incidence outback HF services
• DRM for Band I and Band II is being tested .
• DRM provides state-of-the-art transmit diversity
  to mitigate local indoor multipath at VHF
  frequencies that troubles DAB/DMB-T.

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MF DRM

• Fits into existing channels
• 9kHz bandwidth half existing 18 kHz analog
  bandwidth 2x ch.
• High resistance to impulse noise
• Skywave self fading and multipath distortion at
  fringes can improve performance!
• Provides equivalent coverage to analog service at
  same peak power

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Equivalent Service

• Equivalent service depends on ones definition
  of the minimum service level.
• CCIR take this as 30dB SNR
• Most MF listeners would be comfortable at 23dB
  SNR.
• 20dB SNR is the average performance achieved at
  the currently defined service fringe of 54dBu.
• Punters listening to Racing Radio or Cricket fans
  listening to the 5th day of the Adelaide Ashes
  test would consider 6dB SNR was a usable signal ?

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HF DRM

• Chalk and cheese for international shortwave
  services.
• Half the average power consumed or better.
• Tolerates very long delays that can occur on
  multihop round the world paths.
• Broadcaster can transmit multi lingual programs
  simultaneously.
• Eliminates multipath distortion due to multiple
  hops on outback Vertical Incidence services.

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26 MHz band

• Existing ITU broadcasting band recognized
  internationally.
• Seldom used for SW broadcasting except during
  the peak sunspot years
• Ideal for local coverage DRM
• Has advantages of low noise and minimum spill
  beyond line of site- ideal for generating well
  defined coverage areas.

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MF and 26 MHz DRM

• Majority of receivers operate LF, MF to HF (30
  MHz)
• Transmissions contain alternate frequency
  information so that receivers can
  auto-search-tune.
• MF can be used for wide area blanket coverage
• 26 MHz band can be used as fill-in cells where
  noise and man made interference in heavily built
  up areas makes MF coverage impractical.
• Localized community and commercial radio

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World wide development - HF

• HF Shortwave services- many players
• Over 5000 hours per week are broadcast
• Radio New Zealand- gt 100 hours per week.
• Immediate success

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International Development MF and 26 MHz

• Over 10 full time stations in Europe.
• Not as developed as HF-SW, but growing
• Many countries from Finland to Mexico have both
  MF and 26 MHz tests in progress
• European local market broadcasters considering
  DRM to compliment DAB services where DAB coverage
  is impractical.

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Australian Development of DRM

• Since May 2006 , TJH Systems have had a 24 hour
  facility at Wollongong on 1386 kHz transmitting
  ABC local radio.
• 1kW power using Broadcast Electronics transmitter
  and DRM exciter designed by the author.
• Combined into co-sited MF service DA.

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DRM Wollongong Test

• Demonstrated coverage similar to 2kW ABC service
  next door.
• Can be received daytime in Sydney south of the
  harbour, much of NSW at night. Has been received
  in Adelaide
• Phase one complete, full results online at
  www.drmtrial.com.au
• Phase two through summer investigates impact of
  thunderstorms on service level requirements.

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Wollongong 1kW DRM service measured coverage
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This region DRM and RN affected by nighttime
interference
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Impulse response of Wollongong DRM Test received
in Sydney
Late afternoon
Early evening
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Constellation of Wollongong received in Sydney
early evening- 16QAM mode A
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Radio NewZealand impulse response on 9 MHz
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Aust. development cont..

• Canberra test on 1440kHz by Broadcast Australia.
  Short test and no results of this test have been
  published.
• Radio Australia have an HF facility at Brandon
  which is currently in commissioning stage.
• TJH Systems have 26 MHz tests planned for 1st Q
  2007.

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Planning Issues- MF

• Basic study shows the current spectrum can
  accomodate a DRM transmission for every existing
  program, with the following adjustments to MF
  broadcasting
• a) A reduction of fringe area (54 dBu) night time
  co-channel protection from 30dB to 23dB.
• Existing fringe nighttime SNRs are less than
  23dB due to atmospherics, man made noise, and
  poorly functioning DAs.
• Analog signal quality will be generally unchanged

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MF planning adjustments..

• b) Modulation bandwidth limiting from 9kHz audio
  response to 4.5kHz, thus halving the transmit
  bandwidth.
• The large majority of radios have 10dB bandwidths
  of less than 4.5kHz
• Some have 3dB bandwidth of lt 2.5kHz !
• Modern audio processors can develop very
  aggressive pre-emphasis and brick wall responses
  which largely negates the losses of the
  transmitter high frequency(gt4.5kHz) components

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MF planning adjustments..

• The number of channels available is therefore
  approximately doubled.
• Night time signal quality for all analog
  services will be vastly improved as adjacent
  channel splatter (which is a result of 9 kHz
  spacing and 18kHz transmitted bandwidth) will no
  longer occur.

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MF DRM

• DRM supplimentry licences provided for existing
  services would be allocated to allow a low degree
  of difficulty combining the service into existing
  infrastructure.
• Like ABC services can operate as SFNs providing
  improved coverage with less spectrum utilisation.
• Therefore a statewide program may save over 10
  channels.
• Biggest headache for MF-DRM is the spectral
  pollution that has gone unchecked for many years.

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26 MHz Band Planning

• MF planning is hard 26 MHz band planning can
  be simplified by
• ERP restrictions approx 50W
• HAAT restrictions.
• The right combination will yield reuse at less
  than 200km
• Will provide planning staff simple rules and
  readily computer optimised.
• Skywave propagation features in this band.
• If coverage requirements and power is limited,
  interference by skywave will be minimal.

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Receivers ?

• Receivers tune a station based on a program or
  service name, not frequency or channel.
• Are becoming software defined- that is the
  logic gets programmed at startup time to perform
  a particular decoding function, eg DAB or DRM.
• We are seeing all mode DRM, DAB, AM, FM units.

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Receivers -

• Two streams of receivers currently
• Morphy Richards, Roberts, some German fixed
  receivers
• approx 199 Euros AUD360
• based on Radioscape integrated tuner
• Feature multi mode- DRM, DAB FM and AM
• Performance is acceptable for a first generation
  design.

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Receivers

• Himalaya Hong Kong designed DRM / AM compact
  desktop
• Mayah compact unit ran a short production.
• Other receiver options on the www.drm.org
  website.

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Receivers

• Second Stream Software Decoders-
• Open source software and PC sound card with
  modified conventional tuner .
• DREAM, Fraunhofer decoder
• Enthusiast software defined radios such as
• WINRADIO built in decoder.
• SatSchnieder DRT-1
• Elad FDM77

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Limitations, restrictions.

• Power consumption of these receivers is still a
  full order of magnitude too high.
• This is in line with DAB receivers which have
  similar impractical power consumption for small
  portable devices.
• Power consumption will drop dramatically as ASICs
  are developed.
• DRM is low bandwidth and requires less power than
  older digital technologies.

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Chicken and Egg

• Consumers bitten by AM-Stereo .The industry got
  behind it-, the receiver manufacturers didnt.
• It was easier and more profitable building 1
  radios than competing with a 3 radio.
• Digital radios will never(?) be a cheap as analog
  radios but what is being delivered is generally
  whole lot better than what the analog radio can
  deliver. Apples for apples and consumer education
  required.
• Currently mainstream receiver manufacturers are
  hesitant to commit to large runs (and price
  drops) until they see broadcasters putting
  signals to air.

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Success ?

• FM was a huge success because in the cities, it
  was a tremendous improvement on AM of the day
• FM stereo was modern and hip, receivers were
  available.
• DRM will succeed for the same reason- it is so
  much better than the technology it surpasses .
• DCC/DAT failed as it was not that much better
  than compact cassette for the average consumer
• CD was a success due to its enormous advantages
  over Vinyl.
• There are numerous industry examples of this trend

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The End