digital audio around the world

7
Existing Broadcast Technology Standards S ince the 1970s, research engineers in many coun- tries began looking at how the features and quality of sound available from compact disc (CD) record- ings could be achieved in a commer- cial radio product called digital radio (DR). The British Broadcasting Corporation (BBC) was one of the earliest pioneers and proponents of this technology. DR digitizes the analog signal for broadcast- ing to receivers capable of decoding the digital signal. There are currently four types of DR systems deployed throughout the world. These systems are known as digital audio broadcasting (DAB) system, digital radio mon- diale (DRM), in-band on-channel (IBOC), and satellite digital audio radio. These systems offer the following advantages. n DR reception is largely immune to inter- ference. Digital signal processors depend on receiving the ‘‘0s and 1s’’ necessary for proper decoding into its analog source. If enough ‘‘0s and 1s’’ are not received, the receiver cannot decode the signal, and nothing will be heard from the receiver. n They provide fixed, mobile, and portable reception using simple low-gain antennas. Digital Object Identifier 10.1109/MVT.2010.939105 © DIGITAL VISION Dennis Bodson 24 ||| 1556-6072/10/$26.00©2010IEEE IEEE VEHICULAR TECHNOLOGY MAGAZINE | DECEMBER 2010

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Page 1: Digital Audio Around the World

Existing Broadcast Technology Standards

Since the 1970s, research engineers in many coun-

tries began looking at how the features and quality

of sound available from compact disc (CD) record-

ings could be achieved in a commer-

cial radio product called digital radio (DR). The

British Broadcasting Corporation (BBC) was

one of the earliest pioneers and proponents of

this technology. DR digitizes the analog signal for broadcast-

ing to receivers capable of decoding the digital signal.

There are currently four types of DR systems deployed

throughout the world. These systems are known as digital

audio broadcasting (DAB) system, digital radio mon-

diale (DRM), in-band on-channel (IBOC), and satellite

digital audio radio. These systems offer the following

advantages.

n DR reception is largely immune to inter-

ference. Digital signal processors depend

on receiving the ‘‘0s and 1s’’ necessary

for proper decoding into its analog source. If enough

‘‘0s and 1s’’ are not received, the receiver cannot

decode the signal, and nothing will be heard from

the receiver.

n They provide fixed, mobile, and portable reception

using simple low-gain antennas.Digital Object Identifier 10.1109/MVT.2010.939105

© DIGITAL VISION

Dennis Bodson

24 ||| 1556-6072/10/$26.00©2010IEEE IEEE VEHICULAR TECHNOLOGY MAGAZINE | DECEMBER 2010

Page 2: Digital Audio Around the World

n They are efficient in the use of the limited radio

frequency spectrum.

n They have the capability of operation from terrestrial

and/or satellite transmitters.

n Value-added system features will allow enhancements

such as text, graphics, and still-pictures. These features

provide the opportunity to introduce new innovative

services, such as multimedia radio-with-pictures and

broadcast Web sites on commercial amplitude-modula-

tion (AM) and frequency-modulation (FM) receivers.

The BBC asked Eureka, an international consortium

of broadcasters, network operators, consumer electronic

industries, and research institutes, for guidance on standards

and implementation schemes for DR. In response to this

request, Eureka initiated a project in January 1987 titled DAB

system. This system was developed as the 147 Project for the

European Union and resulted in the European Telecommuni-

cations Standards Institute (ETSI) DAB standard ETS 300 401.

Since then, the International Telecommunication Union (ITU)

has developed several DAB standards for various frequency

ranges. DAB is currently broadcast on terrestrial networks,

with prospects for satellite broadcasting in the future. The

ETSI and ITU standards are shown in Table 1.

A user can receive the terrestrial DAB programs using a

small nondirectional stub antenna. In addition to receiving

audio entertainment, programs can also be accompanied

by text, such as song lyrics, data, pictures, and videos.

Weather forecasts could be accompanied by a satellite

map of the area in which you are listening. This will also

allow you to determine where you are. Emergency

vehicles will be able to find their way to a fire or an acci-

dent because transmitted maps can be regularly updated,

displaying traffic jams and road works and suggested

diversion routes [1].

In order for DR to be successful, it needs to be widely

adopted. The availability of dedicated frequency spectrum

is the principal challenge to adoption especially in the

United States. In Europe, many countries have allocated

spectrum for DR (Eureka 147/DAB system) in the L-band

(1,452–1,492 MHz). The United Kingdom has provided allo-

cations in Band III (217.5–230 MHz), whereas France and

Germany have provided spectrum in both the L-band

and Band III. The United States cannot implement a Eureka

147/DAB system because there is no available spectrum

below 3 GHz for terrestrial use. However, DR can be imple-

mented in the United States through spectrum reuse. This

is discussed later in the paper.

Description of Past, Current,

and Future Technology

Eureka 147 DAB

The Eureka 147 DAB system is a reliable, multiservice, DR

broadcasting system for mobile, fixed, and portable

receivers, is capable of operation at any frequency from

30 MHz to 3 GHz, and can be used on terrestrial, satellite,

hybrid, and cable broadcast networks. It uses simple non-

directional antennas. The DAB signal is specified in ETSI

specification, EN 300 401 (second edition) [5]. Four differ-

ent modes of operation are allowed: mode I (<375 MHz),

mode II (<1.5 GHz), and mode III (<3 GHz) are optimized

for the frequency range in which they are operating. Mode

IV (<1.5 GHz) operates in the same spectral range as mode

II but increases the coverage range at the expense of

poorer Doppler Shift performance. Canada and many Euro-

pean countries have supported the dedicated spectrum

strategy using the Eureka 147/DAB system. Also, this ap-

proach is favored by the FM community.

The Eureka 147 system comprises three main elements:

n masking pattern universal sub-band integrated coding

and multiplexing (MUSICAM) audio encoding

n transmission coding and multiplexing (TCM)

n coded orthogonal frequency division multiplexing

(COFDM) modulation.

MUSICAM uses MPEG2 Audio Layer II encoding as

specified for International Organization for Standards

(ISO) Standard 11172-3. This exploits knowledge of the

properties of the human auditory system, in particular,

DECEMBER 2010 | IEEE VEHICULAR TECHNOLOGY MAGAZINE ||| 25

Page 3: Digital Audio Around the World

the spectral and temporal masking characteristic of the inner

ear. MUSICAM encodes only audio signal components that

the ear will hear. It discards any audio information that,

according to the psychoacoustical model, the ear will not

perceive. The principal of audio masking is shown in Figure 1.

A signal component at 1 kHz distorts and raises the

masking threshold, which defines the level other signal

components must exceed to be audible. If a second audio

component is present and close in frequency to the first, it

will not be perceived the ear unless it is at a higher audio

level than the distorted threshold. Therefore, it is effec-

tively masked by the first component.

TCM is the process by which data for individual services

are combined, or multiplexed, into a single data stream

ready for transmission. As shown in Figure 2, the multi-

plexed DAB frame is comprised of three distinct elements.

n The synchronization channel contains reference fre-

quency and timing information to allow receivers to

synchronize to and decode the received signals.

n The fast information channel contains information

describing the composition of frame and tells the

receiver how to extract and decode the signal.

n The main service channel (MSC) contains the audio

components and/or data packets corresponding to

the different services available within the frame. This

part of the multiplex is essentially the useful payload

of the DAB signal.

The gross data capacity for the entire DAB signal is

approximately 3 Mb/s, of which the MSC occupies approx-

imately 2.3 Mb/s. After allowing for the redundancy pro-

vided by the channel encoding, a net useful payload in the

range of 0.6–1.7 Mb/s is available.

COFDM is a multicarrier digi-

tal modulation scheme used in

DAB systems. It was developed to

improve bandwidth efficiency and

DAB performance in the presence

of multipath interference. Instead

of having a single digitally modu-

lated carrier with a high symbol

rate, COFDM uses multiple carriers

(up to 1,536) spaced at 1 kHz sepa-

ration. Each carrier is independently

modulated using differential quadra-

ture, phase shift keying. The TCM

data are distributed among all the

carriers, occupying approximately

60

40

20

00.02 0.5 0.1 0.2 0.5 1 2

Frequency (kHz)

Sou

ndP

ress

ure

Leve

l (dB

)

5 10 20

AB

C

D

A Normal Threshold of HeadingB Modified Threshold Due to Tone CD Band of Noise Rendered Inaudible by the Presence of Tone C

FIGURE 1 Psychoacoustical masking [5].

TABLE 1 ETSI and ITU DAB standards.

Identification Number Title Published

ETS 300 401 Edition 1 DAB; DAB to mobile, portable, and fixed receivers October 1995ETS 300 401 Edition 2 Radio broadcasting systems; DAB; DAB to mobile,

portable, and fixed receiversMay 1997

ITU-R BO. 1130-4 Systems for digital satellite broadcasting tovehicular, portable, and fixed receivers in the bandsallocated to BSS (sound) in the frequency range1,400–2,700 MHz

April 2001

ITU-R BO. 789-2 Service for digital sound broadcasting to vehicular,portable, and fixed receivers for broadcastingsatellite service (sound) in the frequency range1,400–2,700 MHz

October 1995

ITU-R BS.1114-4 Systems for terrestrial digital sound broadcasting tovehicular, portable, and fixed receivers in thefrequency range 30–3,000 MHz

May 2003

BBC R1 BBC R2 BBC R3 BBC R4 BBCR5L

BBCParl

BBCSport

Synchronization Channel

Fast InformationChannel (FIC)

Main Service Channel (MSC)

• Multiplex Configuration Information (MCI)• Service Information (SI)• Other Data e.g., TMC

• Programme Services • Audio Data • Programme Associated Data (PAD)• Announcement Service• Additional SI, TMC

FIGURE 2 DAB multiplex frame structure [5].

26 ||| IEEE VEHICULAR TECHNOLOGY MAGAZINE | DECEMBER 2010

Page 4: Digital Audio Around the World

1.54 MHz of spectrum. Consequently, the symbol rate on

any individual carrier is much lower and results in a longer

symbol period. This affords some protection against multi-

path echoes where the receiver sees multiple signals from

a transmitter, some of which are delayed because of reflec-

tions from terrain and buildings.

Protection is enhanced by deliberately repeating part

of each symbol during the guard interval, as long as the

delay of the echo signals is less than the guard interval.

This also allows the broadcaster to use a single frequency

network (SFN) of transmitters, where ‘‘man-made multi-

paths’’ are deliberately created by having all the transmit-

ters in the network transmitting the same signal on the

same frequency. Broadcasting on an SFN is an efficient use

of the scarce RF spectrum available—a key advantage of

the Eureka 147/DAB system.

Digital Radio Mondiale

A DRM system uses the COFDM scheme and is designed to

fit within the existing AM broadcast band plan. It is based

on signals of 9-kHz bandwidth. It has modes requiring as

little as 4.5 kHz in bandwidth. The wideband versions offer

the best audio fidelity. It is designed so that the number of

carriers can be varied, depending on factors such as the

allotted channel bandwidth and degree of robustness

required. The robustness of the DRM signal can be chosen

to match different propagation conditions. DRM is the only

standard recognized internationally for high frequency

(HF) (or 3–30 MHz) use. Many existing AM transmitters can

be easily modified to carry DRM signals and can be used for

a range of audio content, including multilingual speech and

music, data, and text.

A DRM system can use three different types of audio

coding, depending on broadcasters’ preferences.

n MPEG4 advanced audio coding augmented by spec-

tral band replication bandwidth extension is used

as a general-purpose audio coder and provides the

highest quality.

n MPEG4 code excited linear prediction speech coding

is used for high-quality speech coding where there is

no musical content.

n Harmonic vector excitation coding speech coding can

be used to provide a very low bit-rate speech coder.

It should be noted that the U.S. Federal Communica-

tions Commission (FCC) has adopted the DRM standards

for U.S. HF Broadcasting [6].

Eureka147 Versus DRM

Radio broadcasters use both AM and FM to meet the

needs of their service areas. In the transition to DR, broad-

casters will, in all likelihood, continue to use existing facili-

ties and equipment due to economic considerations. FM

broadcasters favor Eureka because dedicated spectrum

exists for this system in the very high-frequency (30–300

MHz) portion of the spectrum. AM broadcasters favor

DRM because existing stations can be modified for digital

transmission within existing AM broadcasting bands. In

addition, DRM is the only internationally recognized

standard for HF use.

IBOC DAB System

IBOC refers to a method of transmitting DR broadcast sig-

nals centered on the same frequency as an existing AM or

FM station (referred to as AM and FM systems) but occu-

pying the sidebands above and below the station’s center

frequency. The digital emissions fall within the spectral

emission mask of the AM or FM channel. In 2002, the FCC

selected IBOC technology for the introduction of DR

broadcasting in the United States.

IBOC systems are comprised of four building blocks

similar to the Eureka 147/DAB’s major subsystems [7].

n Audio source coding: An audio codec is a source-

encoding device that filters out those parts of an ana-

log signal that are irrelevant to the human ear. When

decoded, the signal will not be identical to the origi-

nal but will be perceived to be the same.

n Channel coding: The output stream from the audio

codec is encoded using forward error correction (FEC)

and interleaving in the transmission system. This

greatly improves the reliability of the transmitted infor-

mation by carefully adding redundant information used

to correct errors occurring in the transmission path.

Advanced FEC coding techniques have been specifically

designed for AM systems based on detailed interfer-

ence studies to exploit the nonuniform nature of inter-

ference in the AM bands.

n Modulation/demodulation techniques: A modem is a

device that modulates a signal or demodulates it. AM

systems use quadrature AM scheme in conjunction with

orthogonal frequency-division multiplexing (OFDM).

FM systems also uses OFDM modulation but with the

carriers modulated with quadrature phase-shift key-

ing (QPSK) modulation scheme.

n Blending: Blending is a technique employed in IBOC

DAB systems to seamlessly switch between digital-to-

analog signals. Essentially, blending allows transition

from the instantly acquired analog signal (such as

when the receiver is first turned on) to the digital

signal (after the receiver has acquired, decoded,

and processed the signal). Once the digital signal is

acquired, the receiver will transition to it in a seam-

less fashion. Should the digital signal become cor-

rupted the receiver will seamlessly switch to the

analog signal.

DIGITAL RADIO DIGITIZES THE ANALOGSIGNAL FOR BROADCASTING TO RECEIVERSCAPABLE OF DECODING THE DIGITAL SIGNAL.

DECEMBER 2010 | IEEE VEHICULAR TECHNOLOGY MAGAZINE ||| 27

Page 5: Digital Audio Around the World

AM systems and analog AM stations operate in the HF

band. During daytime operations, the coverage area for an

AM system is comparable to, and slightly exceeds, current

analog AM stations. However, during nighttime operations,

HF propagation mode changes from ground wave only to a

combination of ground wave and sky wave propagation.

This combination of propagation modes expands the cover-

age area and introduces multipath interference. Multipath

interference corrupts the digital signal to a point where it

becomes incoherent, thus reducing the effective AM system

range. As a result, analog AM stations have a greater cover-

age area at night than digital AM systems.

The signal footprint for analog FM and for FM-based

systems is about the same. However, the signal penetra-

tion for an FM system is far better than an FM station. In

addition, the FM system provides significant improvements

in signal availability and quality (frequency response, noise,

and distortion).

n Four IBOC DAB systems have been developed in the

United States. Three of these systems were designed

to operate in the existing FM broadcast band, while

one system was designed to operate in the AM broad-

cast band. Developers of FM systems include Amanti

Communications in partnership with AT&T (circa

1991), U.S. digital radio (USADR), a limited partner-

ship between CBS, Gannett, and Westinghouse Elec-

tric (also formed in 1991). USADR also developed an

IBOC DAB for the AM band. Amanti Communications

got out of the business in the mid-1990s. USADR and

Lucent Technologies (which was spun-off from AT&T)

entered into a partnership (circa 1996) for IBOC develop-

ment. This relationship ended in 1998 when Lucent broke

away and formed lucent digital radio (LDR). USADR and

LDR were now competitors. In July 2000, these two com-

petitors merged into the sole surviving developer of

IBOC technology, iBiquity Digital Corporation.

iBiquity uses a technology known as HD radio. In addi-

tion to the benefits of IBOC DAB systems previously dis-

cussed, this technology has the capability to provide:

n wireless data services to include on-demand audio or

the streaming of audio content providing more infor-

mation on station programs, news, weather, and traf-

fic; other services can include the display of artist

and song information and mobile commerce options

n backward and forward compatibility, which allows a

user to purchase a digital receiver that will receive

traditional analog broadcasts from stations who have

not convert to HD radio and digital broadcasts from

stations that have.

Transition to DR will require broadcasters to install

new transmission equipment. During the transition,

broadcasters will operate in a ‘‘hybrid’’ mode, broadcast-

ing both analog and digital signals. During hybrid opera-

tions, stations will broadcast the same programming in

both analog and digital formats. New receivers being

developed will incorporate both modes of reception,

where the receiver will automatically switch to the analog

signal if the digital signal cannot be decoded or is lost by

the receiver.

Software-Defined Radio

A software-defined radio (SDR) is equipment that can be

reprogrammed quickly to receive signals within a wide

range of frequencies, and in any transmission format or

set of standards [4]. SDRs currently exist and examples

include personal digital assistants (PDAs), cell phones,

and amateur radios. SDR provides an efficient and compa-

ratively inexpensive solution to the problem of building

multimode, multiband, or multifunctional wireless devices

and can be considered an enabling technology that is

applicable across a wide range of areas within the wireless

industry. Features of an SDR include:

n standard, open, and flexible architectures for a wide

range of communication products

n enhanced roaming by extending the capabilities of cur-

rent and emerging commercial air-interface standards

n over-the-air downloads of new features and services,

such as software patches

n unified communications across commercial, civil, fed-

eral, and military organizations.

An SDR system can be viewed as one in which the base-

band processing as well as digital down conversion/digital

up conversion modules are programmable. Availability

of smart antennas, wideband RF front-ends, wideband

A/D and D/A converters, and ever increasing processing

capacity of digital signal processors and general-purpose

microprocessors have fostered the development of multi-

band, multimode radio systems.

Figure 3 illustrates the software architecture of a typi-

cal SDR system. The system uses a generic hardware plat-

form with programmable intermediate frequency and

baseband modules and analog RF modules. The operating

environment performs hardware resource management

activities such as allocation of resources to different appli-

cations, memory management, interrupt servicing, and

providing a consistent interface to hardware modules for

use by applications. In an SDR system, the software mod-

ules that implement link-layer protocols and modulation/

demodulation operations are called radio applications

and provide link-layer services to higher layer communi-

cation protocols such as wireless application protocol

and transmission control protocol/Internet protocol.

TCM IS THE PROCESS BY WHICH DATA FORINDIVIDUAL SERVICES ARE COMBINED, ORMULTIPLEXED, INTO A SINGLE DATA STREAMREADY FOR TRANSMISSION.

28 ||| IEEE VEHICULAR TECHNOLOGY MAGAZINE | DECEMBER 2010

Page 6: Digital Audio Around the World

Satellite Digital Audio Radio Services

There is a new type of DR broadcasting called satel-

lite digital audio radio services (SDARSs). With SDARS,

listeners will be able to tune in to the same radio sta-

tions anywhere in the United States. There are two DR

systems providing SDARS, Sirius Satellite Radio, and XM

Satellite Radio.

From a technical standpoint, the Sirius and XM Satellite

systems are unique in a number of ways. In the XM system,

two satellites in a conventional geostationary orbit, one at

85� W longitude and the other at 115� W longitudes, are

used. These locations afford optimum coverage of the

United States. Sirius uses three satellites in highly elliptical

orbits rising and setting approximately every 16 h. As a

result, two of the three satellites are visible to receivers in

the United States at any given time. Because of their orbits,

the Sirius satellites are higher in the sky and less likely to

be blocked by buildings, trees, or mountains.

Three specific techniques, each representing a differ-

ent kind of redundancy, spatial, frequency, and time

Higher Level Protocols (WAP, TCP/IP)

Radio Applications (Link-Layer Protocols,Modulation/Demodulation)

Operating Environment (Hardware Resource Management,Memory Management, Interrupt Management)

Hardware Resources (DSPs, FPGAs, Microprocessors,Memory, Analog RF Hardware Including Antenna)

FIGURE 3 Architecture of software components in a typical

SDR system. WAP: wireless access protocol; TCP/IP: transmission

protocol procedure/Internet Protocol; DSP: digital signal processor;

and FPGA: field programmable gate array.

TABLE 2 U.S. Satellite digital audio radio service [3].

Parameter

Satellite radio

CommentsSirius XM

In orbitNo. satellites (longitude) 3 (nominal 100� W) 2 (85� and 115� W) Sirius satellites are in a highly

elliptical orbit, rising andsetting every 16; hours; XMtypes are geostationary

Uplink frequencies 7,060–7,072.5 MHz 7,050–7,075 MHz Sirius also uses Ku-band(14–12 GHz) uplink to feedrepeaters

Downlink frequencies 2,320.0–2,324.0 MHz and2,328.5–2,332.5 MHz

2,332.5–2,336.5 MHz and2,341.0–2,345.0

Redundant downlink signalsare for spatial/frequency/timediversity

Satellite elevation angle 60� 45� Typical

On landLocation New York City Washington, D.C. —No. studios 75 82 In main facilityNo. terrestrial repeaters 105 (46 markets) 1500 (70 markets) Approximate numbersRepeater equivalentisotropic radiated power

Up to 40 kW 90% are 2 kW —

Other characteristicsNo. CD-quality (64-kb/s)channels

50 Lower-quality services use0.5–64 kb/s

No. news-talk-sportschannels

50 System is reconfigurable onthe fly

Satellite modulation TDM-QPSK Each carrier is about4 MHz wide

Terrestrial repeatermodulation

TDM-COFDM Carrier ensemble is about4 MHz wide

Channel coding scheme Concatenated Error-correcting Reed-Solomonouter code and rate 1/2convolutional inner code

Source coding scheme Lucent Perceptual Audio Coder Nominal rate for top-qualitymusic: 64 kb/s

Transmission Rate 4.4 Mb/s 4.0 Mb/s Before channel coding

It should be noted that XM and Sirius Merged on 29 July 2009 [8]. TDM ¼ time-division multiplexing. Source: Sirius Satellite Radio, XM Satellite Radio.

A DRM SYSTEM USES THE COFDM SCHEMEAND IS DESIGNED TO FIT WITHIN THE EXISTINGAM BROADCAST BAND PLAN.

DECEMBER 2010 | IEEE VEHICULAR TECHNOLOGY MAGAZINE ||| 29

Page 7: Digital Audio Around the World

diversity, all are used by the SDARS services to enhance

performance.

n Spatial diversity comes from multiple satellites trans-

mitting essentially identical signals from two, widely

spaced locations in orbital planes and periods. An

SDARS receiver in a moving vehicle often will see

multiple satellites and be continuously receiving and

processing the signals from both. There will be times

when at least one of the satellites will be blocked by

an obstacle; in this case, the receiver will have to rely

upon the signal from other (unblocked) satellites.

n The two other forms of diversity are frequency diver-

sity and time diversity. Frequency diversity is realized

by each satellite broadcasting the same signal but in

different frequency bands. This can help to combat

problems associated with multipath fading, where fad-

ing is frequency selective and usually limited to one

band or the other. Time diversity is implemented by

introducing a time delay in the signals broadcast

from the satellites and the signals broadcast from

their terrestrial repeaters. Time delays compensate

for differences in the distance between the satellites

and terrestrial repeaters.

The characteristics of Sirius and XM satellites radio

systems are shown in Table 2.

Observations and Conclusions

DR (or DAB) has been around for several decades but

only now is it being adopted and implemented by the

commercial broadcast community. There are four types

of systems: Eureka 147, DRM, IBOC, and Satellite Digital

Audio Radio. There are two types of implementation

strategies: use of dedicated spectrum and reuse of exist-

ing spectrum for AM and FM broadcasting. Eureka 147

uses dedicated spectrum; DRM and IBOC reuse existing

spectrum. In addition, SDAR makes use of terrestrial as

well as satellite systems (XM and Sirius). Digital tuner

costs vary from US$150.00 to US$1,000.00. Table 3 shows

a comparison of each type of system.

Although a principal purpose of DR is the enhance-

ment of audio quality, this technology offers additional

features such as the ability to integrate and broadcast

text, data, and video, weather service information, and

satellite maps of your location. In addition, DR technol-

ogy is adopting the use of software to defined radio

capabilities and features that will result in longer equip-

ment life cycles and using common equipment in

diverse applications.

Author Information

Dennis Bodson received his B.E.E. and M.E.E. degrees

in electrical engineering from The Catholic University of

America, Washington, DC, his Master’s degree in public

administration from the University of Southern Califor-

nia Washington Center for Public Affairs, DC, and his

Ph.D. degree in electrical engineering from California

Western University in 1961, 1963, 1976, and 1985, respec-

tively. He recently retired from federal service as the

chief of the Technology and Standards Division of the

National Communications System and has since been

self-employed as a consulting engineer in the informa-

tion technology field. He has published more than 60

technical articles, two books, and six patents. He won

several awards from both industry and government. He

is currently the director of the Roanoke Division of the

Amateur Radio Relay League and past president of the

IEEE Engineering Management Society and the IEEE

Vehicular Technology Society. He is a Fellow of the IEEE,

the IET, C’Eng UK, the Radio Club of America, and the

Washington Academy of Sciences.

References[1] D. M. L. Witherow and P. A. Lowen, ‘‘Digital audio broadcasting—The

future of radio,’’ in Proc. IEE Int. Broadcasting Convention Conf., Sept.14–18, 1995, pp. 57–61.

[2] H. W. H. Tuttlebee and D. A. Hawkins, ‘‘Consumer digital radio: Fromconcept to reality,’’ Electron. Commun. Eng. J., vol. 10, no. 6, pp. 263–276, Dec. 1998.

[3] D. H. Layer, ‘‘Digital radio takes to the road,’’ IEEE Spectr., vol. 38,no. 7, pp. 40–46, July 2001.

[4] H. Newton, Newton’s Telecom Dictionary, 21st ed. San Francisco, CA:CMP Books, 2005.

[5] A. J. Bower, ‘‘Digital radio—The Eureka147 DAB system,’’ Electron.Eng., pp. 55–56, Apr. 1998.

[6] FCC Adopts DRM System for US HF Broadcasting, May 10, 2005.[7] National Radio Systems Committee (NRSC), Digital Audio Broadcast-

ing (DAB) Subcommittee Report‘‘Evaluation of USA digital radio’ssubmission to the NRSC DAB subcommittee of selected laboratoryand field test results for its FM and AM band IBOC system,’’ Appendi-

ces D and IApr. 8, 2000.[8] ‘‘XM and Sirius Merger,’’ July 29, 2008.

TABLE 3 Digital radio feature characteristics.

Feature Supported in DR Technology

Eureka147/DAB DRM IBOC Satellite

Reuse of radiospectrum

No Yes Yes No

Radio spectrumspecifically allocatedfor DR

Yes No No No

CD quality sound Yes Yes Yes YesSupport terrestrial-based DR

Yes Yes Yes No

Wireless dataservices (text,graphics,weather, etc.)

Yes Yes Yes Yes

Backwardcompatibility withanalog radio

No Yes Yes No

Interferenceimmunity

Yes Yes Yes Yes

Equipmentavailability

Yes Yes Yes Yes

30 ||| IEEE VEHICULAR TECHNOLOGY MAGAZINE | DECEMBER 2010