The Future of Radio Transmission is Digital


  The limitations of the spectrum and transmission difficulties make analogue unexpandable. In Hong Kong we have seven territory-wide stations on FM, and that is it. Seven stations for nearly seven million people. Hilly landscape and dense high-rise urban development mean that each channel needs several transmitters to cover the whole territory, and the nature of FM means that each transmitter requires a different frequency. The spectrum allocated to FM transmission is limited. It has to be shared by international agreement with Macau, Shenzhen and Guangdong. It is full.

  AM is an unsatisfactory alternative. Transmission sites and towers are huge and expensive to run and when they break down many spare parts are no longer available. The signal is susceptible to interference and distortion, reception is poor. It is an obsolete technology.

  The prospect of digital transmission has been around since the early nineties. Digital signals require far less transmission power, they can be delivered without any loss of quality, several signals can occupy one frequency carrier, signals can be re-transmitted on the same frequency, extra services in the form of text and pictorial data can be provided and the audio can be delivered in CD quality.

  Digital has the potential to offer consumers territory-wide high-quality transmission of all existing radio stations plus dozens of new ones without distortion and interference, as well as the transmission of text and pictorial data either associated with the radio programme(PAD)(artist and album details for instance), or non-programme associated data (non PAD)such as finance, weather or even classified advertising. Listeners will be able to interact with the programming (quiz response, accessing news or weather on-demand, choice of language), they will even be able to instantly record a particular song as an MP3 file and access linked web-sites. They will be able to access DAB on their PC, on a hi-fi tuner, on a car radio, and a Palm style portable receiver. For the industry DAB offers public broadcasters a means of providing more audio services (more choice) with superior coverage and sound quality with cheaper transmission and operations. Commercial outfits can operate more high quality channels plus data services and a new market for transmission equipment and radios.

DAB Development

  Digital sound broadcasting is at different stages of development, and several countries or international consortia are developing different systems. The term DAB is normally taken to mean the system developed by the Eureka 147 consortium and is in wide use throughout Europe, Canada and Singapore, and is currently being tested in China (including Hong Kong)India, South Africa, Scandinavia, Australia and Malaysia. It is able to provide localised services, audio in CD quality plus data services, mobile reception at up to 150 km/h and flexible multiplexing. It can operate on L band (1452-1492 MHz)or Band III (VHF)depending on local spectrum availability. The USA are testing the IBOC DAB( In Band On Channel )- a hybrid that can transmit digital signals alongside existing analogue signals, and the Japanese are working on a narrow band approach for terrestrial DAB - Integrated Services Digital Broadcasting - ISDB-Tn, as well as Digital System E that provides satellite and complementary terrestrial on-channel repeater services for high quality audio and multimedia data. They currently have a stronger interest in WAP transmission technology as they feel its interactivity will have more consumer interest than DAB. WorldSpace - a multi-national group with its head office in Washington DC provides satellite DAB via 3 geostationary satellites to vast areas of the globe with a signal that can be picked up from portable receivers that are currently on the market. It is testing terrestrial augmentation for areas where the signal is weak. DRM is a consortium of many international groups (China is a founder member) developing a digital system in the bands below 30 MHz - short, medium and long wave transmission bands (AM) which will allow the use of existing transmitter equipment and give longer range signals with greater penetration albeit without CD quality sound.

  All these systems have their merits, but they also have drawbacks. Satellite transmission for instance, whilst good for remote rural areas, is too weak to penetrate dense urban development or compete with terrestrial signal competition. And whilst DRM's plans to utilise AM frequencies may give greater penetration and cheaper transition to digital, the sound quality is not good and AM is now considered to be an obsolete technology.

The UK

  In the UK, the public broadcaster (BBC) and the commercial national multiplex Digital One - the two national multiplexes - are working alongside each other to stimulate digital development. The BBC has been pioneering DAB since 1995 and has recently had its funding secured for the next seven years. The digital network reaches 70% of the population, with 85% planned by the end of 2001. Government policy has encouraged the transition to digital by providing the necessary spectrum and an incentive driven regulatory framework that provides a stable market. Digital One's licence runs for 24 years for instance as they do not expect to turn a profit until 2007. They are backed by powerful shareholders. They carry Virgin Radio, Classic FM and Talksport and have seven brand new national stations - rock, chart, news, AC etc. They see radio as an increasingly popular medium and the demand for digital will come from traditional radio listeners who are seeking more content. By the end of this year there will be 37 regional and national multiplexes. Each month the Broadcasting Authority offers new regional multiplexes for open tender and existing radio companies are grouping together with financial backers to bid for the licences.

Digital transmission offers audio broadcasting a promising prospect.


  Singapore is using the advent of digital as a vehicle to promote its own image internationally. The Singapore Broadcasting Authority produces glossy brochures and does much promotional work which acts as education for the general public and industry to help them understand the potential of digital. It is proud of the fact that with the issuing of a DAB licence to the Radio Corporation of Singapore in 1999 it became the first country in Asia to have DAB services. RCS's 'Smart Radio' re-transmits four of its existing channels plus Bloomberg Radio and a mixed 'preview' channel from one transmitter. The SBA is pro-active in DAB licencing with a light-touch approach - "constructive not constrictive". It offers 'Early Bird" incentives to offset the high production costs and has established a S$5 million Digital Broadcasting Development Fund to encourage research and development - particularly in multi-lingual services.

  On the industry side a Singapore company called Plexus is offering a whole new range of DAB related hardware and software, from multimedia studios where the presenter can operate pictorial, text and data information while presenting a radio programme, through transmission devices and receivers, to e-mail and web extractors, jukebox services and individual DAB enclosed networks for public viewing in transportation systems, hospitals etc.


  China has co-operated closely with the European community to promote the development of DAB in China. It has set up two DAB (or DMB as they call it - Digital Multi-Media Broadcasting) pilot networks in Guangdong and the Beijing-Langfang-Tianjin areas. Its Single Frequency Network in Guangdong is composed of three transmitter stations, one network central station, one data business and management centre and one signal distribution and transmission system with a wireless network covering the Pearl River Delta Zone carrying the audio signals, and three data services which include finance, traffic and city information. It operates on VHF Band III. In view of the size of the country, China National Radio sees satellite radio as the only way to reach remote areas and to this end is testing Worldspace Digital Sound Broadcasting. At the same time China, as a founder member of Digital Radio Mondiale (DRM) is developing digital transmission on AM frequencies for better penetration over long distances. Its use of existing transmitter equipment and low power requirement makes the transition from analogue to digital cheaper and easier.

Hong Kong

  Hong Kong has been running test digital signals since 1998 on L-Band (1468.368 MHz) - originally from two transmitter sites - Mount Gough and Beacon Hill. Outdoor reception tests were found to be satisfactory, but indoor reception disappointing. This could be because of the density of high rise buildings, but equally the power output (200 watts) was considerably lower than tests in other countries. (Guangzhou 600 watts, Foshan and Zhongshan 1200 watts).

  Lack of availability of home receivers is considered a major blockage to digital development. Receiver roll out has been disappointingly slow for many content providers world wide. BBC Chairman Sir Christopher Bland for instance feels that they went into the digital market too early.

  It is a vicious circle. Manufacturers will not commit themselves to starting up costly production lines until they see public demand. Public demand will not happen until all existing radio stations plus new ones as well as data information services are provided and receiver sets are cheap, but the content providers will not put existing or new programming on until receiver sets proliferate.

  Hong Kong has dipped its toe into the digital waters with little enthusiasm.

  One reason may be that the government has not recognised the potential of this new and exciting media opportunity for both commercial and public radio and data services. It may also be waiting to see how the G3 network takes off and whether that may prove a more popular way of receiving audio on a portable receiver.

  But WAP reception in practice has not matched the claims of the manufacturers. Connection on the move and inside buildings is unreliable, and the complications of operation plus limited information access has put customers off. Beijing, which saw China as the perfect platform for WAP with visions of being the world's largest computerless Internet market, has encountered market apathy with the general public not knowing what to use it for or have any idea why they would want it. Its launch in Europe has been lacklustre( the BBC started a WAP service but have stopped it through lack of interest ) and in the states it hasn't got beyond the trial stages.

  DAB offers an enclosed broadcasting system which is culturally specific. It is cheap to transmit and economic on spectrum use. It offers instant access( no searching for URLs )multi-choice, interactivity, PAD and non-PAD, high-quality audio and complete city-wide coverage.

  It has great commercial potential. In Hong Kong, as has happened in UK and Singapore, government regulating and telecommunications authorities need to set up the right multiplex operating platform and offer incentives for consortia to tender for licences. Equally, RTHK as the public broadcaster, should operate its own multiplex to enhance the quality and range of its public service provision. Thus the commercial and public sector would work simultaneously to promote the significant advantages of digital.

Other Transformation

  Digitalisation is not just about transmission. Programme providers need to digitalise the workplace and develop the digital skills of programme production. Digital work stations linked to digital playout and storage systems reduce the need for expensive studios and costly mechanical equipment with high maintenance costs. Staff need to be retrained to become multi-skilled - technicians need to have on-air presentation and IT skills, presenters need to be IT familiar and managers must have presentation, IT and technical knowledge. Workstations and play-out systems need to have text and pictorial output capabilities, presenters and reporters must start thinking of working with pictures as well as sound. Automation and semi-automation systems must be incorporated and utilised to allow the content providers to provide extra services without taking on extra manpower. The demand for the extra services on digital would open up the receiver manufacturing market, prices would drop as demand increases, programme content would grow and within a few years we may wonder why we ever bothered with AM or FM.

  The broadcasting industry is renowned for its over-use of acronyms. There is one in particular though that has appeared on the scene and is gaining popularity. ASO. What does it stand for? Why, Analogue Switch Off of course. 

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