Deployment of Digital Audio Broadcasting in the U.S. and Abroad

1
Deployment of Digital Audio Broadcasting in the
U.S. and Abroad

• John Kean
• NPR Labs, Washington DC
• jkean_at_npr.org

2
Frequency Bands of Terrestrial DABSource World
Broadcasting Unions
3
DAB (Eureka-147)

• Initiated as a European research project in the
  1980s for mobile, portable and fixed
• 3 main elements, all ETSI TS 102 563
• Digital transmission coding multiplexing (5-7
  services)
• COFDM modulation, 1.54 spectrum
• Mostly L-Band, but in U.K., 12.5 MHa of Band III
  (217.5-230)
• MUSICAM (MPEG-2 layer III) perceptual coding

4
International Rollout of DAB, DAB World DMB Forum

• Now in more than 20 countries, gt1000 stations
• Reaching gt100 million in Europe, 500 million
  worldwide
• UK DAB listeners estimated at 20 million
• Shown to be 3.2 times more spectrum-efficient
  than FM
• Also DMB (Digital Multimedia Broadcasting)
• Usually considered a digital mobile video
  platform
• MPEG-2 transport stream packets with additional
  block coding
• In use in Korea, Germany, numerous test countries
• DAB standardized in 2006
• Added new HE-AAC v2 audio codec, surround sound
• New frequency bands
• Launches in Australia, Switzerland, Italy,
  Germany, etc.

5
International Rollout of DAB Variants
source World DMB Forum
Regular services Australia, Belgium, China, Czech
Republic, Denmark, Germany, Hong Kong, Malta,
Netherlands, Norway, South Korea, Sweden,
Switzerland, United Kingdom, Canada Trials or
regulation to permit Austria, Brunei Darussalam,
Chinese Taipei, Croatia, France, Ghana, Hungary,
Indonesia, Ireland, Israel, Italy, Kuwait,
Malaysia, New Zealand, Poland, South Africa,
Spain, Vietnam
6
L-Band Frequencies Assigned to DAB
Block Center Frequency (MHz)
LA 1452.960
LB 1454.672
LC 1456.384
LD 1458.096
LE 1459.808
LF 1461.520
LG 1463.232
LH 1464.944
LI 1466.656
LJ 1468.368
LK 1470.080
LL 1471.792
LM 1473.504
LN 1475.216
LO 1476.928
LP 1478.640

• Used for T-DAB (terrestrial) broadcasts
• WorldSpace satellite broadcasts in the
  14671492 MHz L sub-band
• Canada uses slightly different central
  frequencies for L-band DAB
• In many European countries DAB is limited to part
  of Band III, due to television and mobile two way
  radio 

7
Digital Radio Mondiale

• DRM is an international non-profit consortium
• Radio France Internationale, TéléDiffusion de
  France, BBC World Service, Deutsche Welle, Voice
  of America, Telefunken (now Transradio) and
  Technicolor SA
• Open-standards design and implementation of
  platform
• Principle bandwidth is limited element, and
  computer processing power is cheap
  modern CPU-intensive RF audio compression
  techniques enable more efficient use of available
  spectrum
• Can deliver FM-comparable sound quality on
  frequencies below 30 MHz (LW, MW, SW)

8
DRM One-Fifth the Power Required for AM
BBC Report on Plymouth UK tests
9
Digital Radio Mondiale

•  64-QAM, 16-QAM and 4-QAM schemes
• 6.1 - 34.8 kbit/s for a 10 kHz channel
• 72 kbit/s using standard 20 kHz channel
• Allows very-long-distance signal propagation (a
  few watts on 26 MHz to 100s of kW on LW)
• Decodable with PC software and sound card

• Endorsed by the ITU, approved as international
  standard
• Australian govt. placed embargo on 6 - 26 MHz
  potentially suitable for use by DRM until
  spectrum planning can be completed
• U.S. FCC rules part 73.758 (for HF-band broadcasti
  ng) "For digitally modulated emissions, the
  Digital Radio Mondiale (DRM) standard shall be
  employed."

10
DRM New, for VHF Transmission

• 30-174 MHz VHF band
• 100 kHz channelization
• COFDM, 64-, 16-, 4-QAM
• Using HE-AAC audio codecs
• SFNs supported
• Up to 4 program services
• 1 station, 1 frequency
• May coexist near linked FM signal, also Band III
• ETSI, official in 2009

11
DRM New, for VHF Transmission

• Internationally agreed norms for FM band (88-108
  MHz) protection
• High power field trial in UK, Sri Lanka etc.
• ITU standardization
• Limited choices in receivers
• Uncertain numbers of listeners

12
HD Radio

• In-Band On-Channeldigital transmission in FM
  and AM bands
• Only system approved for digital AM FM by FCC
• Outgrowth of DAB research in mid-late 1990s
• Led primarily by large U.S. broadcast interests
• Desire for one-to-a-channel assignment
• Private company (iBiquity Digital) established
  and branded as HD Radio

13
HD Radio

• Originally referred to a IBAC (In-band
  Adjacent-channel) system FM shown

14
HD Radio

• Implementation benefits
• FM receivers not made obsolete
• Propagation of FM band superior to L-band
• Presumed ability to utilize existing transmitter
  system, avoid development of new band
• National Radio Systems Committee support
• ITU Recommendation BS.1114-4, adopted May 2003,
  classified as Digital System C

15
HD Radio Development

• In U.S. 2100 stations, gt95 FM, lt5 AM
• Adoption in Mexico, Phillipines, so far
• Advanced interest in several countries

Source iBiquity
16
HD Radio Development

• Initial estimates of coverage at 1 power of FM
  were exaggerated
• Indoor and portable coverage were substantially
  smaller than FM host
• NRSC and iBiquity promoted and won power increase

17
HD Radio Development

• In 2010, FCC adopted a blanket increase
• 4X power increase, and up to 10X under signal
  clearance conditions to first-adjacent stations
  (determined in research by NPR Labs)
• Interference remediation required for proven
  digital-to-analog FM interference cases
• No U.S. standards to protect HD Radio from
  interference
• IBOC DAB is subject to received interference
• FM rules consider only analog-to-analog
  allocations are ignorant of analog-to-digital
  issues

18
Summary

• Technical evolution of DAB in all forms has
  arguably been slow
• Interest by consumers to DAB in the U.S. is still
  weak after a decade, despite the large number of
  digital FM stations in operation
• Analog FM remains the majority radio service
• Will the future of digital audio broadcasting
  move faster? Will it collide with other forms of
  wireless digital media?