WHAT IS DIGITAL RADIO?
Digital radio is a new method of assembling, broadcasting and receiving communications services using the same digital technology now common in many products and services such as computers, compact discs (CDs) and telecommunications.
Digital radio can:
- provide for better reception of radio services than current amplitude modulation (AM) and frequency modulation (FM) radio broadcasts;
- deliver higher quality sound than current AM and FM radio broadcasts to fixed, portable and mobile receivers; and
- carry ancillary services-in the form of audio, images, data and text-providing
- program information associated with the station and its audio programs (such as station name, song title, artist's name and record label),
- other information (eg Internet downloads, traffic information, news and weather), and
- other services (eg paging and global satellite positioning).
A fundamental difference between analog and digital broadcasting is that digital technology involves the delivery of digital bit streams that can be used not only for sound broadcasting but all manner of multimedia services.
What systems are available?
There are two major digital radio systems currently under consideration-the European Eureka 147 system and in-band systems currently under development in the United States of America. (There are also a number of digital systems that use satellites for delivery of services.)
Eureka 147 was developed in Europe by a consortium of broadcasters, Government research bodies and a segment of the electronic manufacturing industry. Eureka 147 is being adopted in Europe and Canada to replace existing analog services.
Depending upon the particular technical and spectrum arrangements adopted, the Eureka 147 system may offer:
- use of one receiver for both terrestrial and satellite reception;
- the commencement in early 1998 of markets for domestic receivers, and transmission and studio equipment;
- higher quality sound than AM or FM radio, providing an appropriate bit rate is used;
- the capability to reconfigure services for different programming requirements;
- greater flexibility in coverage than analog services;
- more reliable reception to fixed, portable and mobile receivers than current AM or FM radio;
- program-associated information and ancillary multimedia services;
- more effective use of spectrum than analog services;
- reduced radiated power requirements for coverage of a given area than analog services;
- the ability to operate over a range of frequency bands; and
- generally lower or comparable capital and operating costs than AM or FM radio.
The two main in-band systems under development in the USA are In-Band On Channel (IBOC) and In-Band Adjacent Channel (IBAC). The IBOC system transmits a digital signal simultaneously within an existing analog AM or FM signal. The IBAC system transmits a digital signal within unused spectrum adjacent to that used by existing FM signals. In-Band Reserve Channel (IBRC), which is based on using "spare" spectrum not able to be used for other services, is also a possibility.
What receivers are needed?
Reception of digital radio requires new receivers to separate and decode the transmitted signals. Many receivers are likely to incorporate a screen as well as the traditional speakers to allow for reception of the new multimedia applications.
Eureka 147 receivers are currently being manufactured for the European and Canadian markets. The first consumer receiver models were displayed at the World of Consumer Electronics fair (Internationale Funkausstellung, IFA) in Berlin in August 1997.
Reports from the United Kingdom suggest that the Eureka 147 digital radio car receivers will be the first receivers to be made available to consumers and are expected to be on the market early in 1998, followed by home hi-fi receivers. Portable digital radio receivers are expected in the following year. The first consumer digital radio receivers are expected to be priced at around the cost of a top of the line car radio, that is around $1,000.
How does it work?
Digital radio systems use advanced digital techniques to convert the audio signal from an analog waveform to a digital signal, sampling the amplitude of the wave and creating a stream of ones and zeros which accurately represent the original sound. The sampled information is digitally compressed, and several audio channels are brought together and encoded into a single data stream by means of a multiplex. Data and other services are added. The whole digital stream is referred to as an ensemble. Receivers separate and decode the signals in the digital stream.
What spectrum will digital radio use?
Using the Eureka 147 system, each multiplex occupies 1.5 MHz of spectrum and is able to provide: five CD quality programs; or around six FM quality services; or around twelve AM quality services; or around thirty voice channels; or some combination of these. A greater number of digital than analog services can be located in a given amount of spectrum, and digital services require less power to cover a given area than analog services. Also, the signals can be dynamically reconfigured, ie a high quality service can be readily switched to a number of lesser quality services or vice versa.
Eureka 147 technology can operate throughout an extensive range of frequencies. While the spectrum band known as the L band is reserved internationally, the existing television spectrum, VHF band III, is used extensively in Europe. This means that there are a number of options for locating digital radio services in the radiofrequency spectrum, thus increasing the chances for sufficient spectrum to be allocated to provide for a wide range of services.
In-band systems operate either in or adjacent to existing radio signals.
What about broadcasting the analog and digital services simultaneously?
Analog and digital services can be broadcast simultaneously ("simulcasting") until digital services become commonplace so that viewers have a reasonable period to purchase digital radio receivers. However, some in-band systems have been reported as causing some interference to the host analog signal.
What is happening overseas?
- A total of 17 European countries are introducing digital radio using the Eureka 147 system, with full time broadcasts under way in Sweden, Norway, Germany, France, and the United Kingdom.
- Canada is migrating all existing broadcasters to digital radio using the Eureka 147 system.
- Many Asian countries, including Japan, Singapore, and Malaysia, are considering or planning the introduction of digital radio.
- The USA has yet to decide on the introduction of digital radio.
What is being done in Australia?
In 1995, the Government established an industry committee, the Digital Radio Advisory Committee (DRAC), to examine policy and technological issues associated with the introduction of digital radio services in Australia. The Committee had an independent chair, and membership drawn from broadcasting and electronics manufacturing industry bodies, telecommunications carriers, the Communications Law Centre and Government agencies.
The Committee released its final report in August 1997.
DRAC recommended the introduction of digital radio in Australia using the Eureka 147 system, with planning proceeding in the existing L band frequency allocation, though consideration should be given to the possible advantages of using VHF spectrum. It further proposed that planning should commence as soon as possible, with services to commence in 2000. All existing broadcasters should have a right to automatic access to digital radio broadcasting with the same licence conditions as apply under analog technology. Detailed planning should provide capacity for other narrowcasters and other services as a priority.
Following his initial consideration of the report, the Minister for Communications, the Information Economy and the Arts, Senator Richard Alston, announced his support for the introduction of digital radio in Australia in his opening address to the Annual Convention of the Federation of Australian Radio Broadcasters on 19 September 1997.
The Minister provided in-principle support for the use of the Eureka 147 system, with initial planning of services to occur in the L band. He indicated that incumbent broadcasters would be offered the opportunity to move to digital, and there would be opportunities for new entrants as well.
Following from this broad policy base, the next stage in the introduction of digital radio in Australia involves the adoption of appropriate technical standards, the development of a spectrum allocation plan, and the preparation of a legislative framework, following further consultation with interested parties.
Copyright © Commonwealth of Australia 2000· Last update: 11-Nov-98
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