Digital Terrestrial Broadcasting for Hong Kong


  Digital terrestrial TV broadcasting is an integral part of the digital revolution that is sweeping the world. In Hong Kong, we have already been exposed to it by way of personal computers, digital portable phones, internet, DVD, VOD and the many other systems and devices that have become part of our way of life. This has resulted in a blurring of traditional boundaries and presented legislators, broadcasters and viewers with new challenges and directions.

Analogue Limitations

     The present analogue TV broadcasting technology is based on the original black and white TV technology of the 1940's and reflects the limitations of that era. When colour was introduced, it was designed as "add on" to allow people still to use their black and white receivers. As a result, the colour system also suffers from all the inherent limitations of the black and white system and represents a compromise solution at best.

     Many of the problems seen in the existing broadcasting system are common to analogue systems. Analogue systems are prone to degradation because distortions such as noise and interference can easily affect the signal being transmitted. Digital signals do not have this problem, as they are able to isolate the interference and distortions and so retain the original information without any change even after many generations of copying or when transmitted by cable satellite or terrestrially.

     The amazing advances in silicon chip development during the past few years have permitted the introduction of digital technology on a scale that was previously impossible. As part of this new technology, sophisticated digital compression systems have been designed that have enabled several standard digital television signals to be squeezed into the space presently needed for one standard analogue television program. They have also allowed a High Definition TV (HDTV) channel, offering widescreen pictures and surround sound with quality similar to that seen in movie theatres, to be transmitted in the same analogue space.

     Other improvements offered by this new digital technology include the ability to provide additional services such as multimedia channels together with the main service, transmission of television programs to moving vehicles, and elimination of picture distortions such as "ghosts" and "snow".

Competing Standards

     Unfortunately, the hope that with this digital technology would also come a world standard have not come true. Instead, once again the technology has divided along political lines with three competing standards from the US, Japan and Europe emerging, based on regional interests. Each system has been designed primarily to cater for conditions in its respective region but promoted for use throughout the world. As would be expected, the countries promoting these standards are rapidly introducing this new technology, with the US and UK starting transmissions later this year and Japan in 2000.

     All have adopted a "parallel" implementation plan whereby the new digital services will be run simultaneously with the existing analogue services for a number of years, to allow viewers a period of grace in which to replace their analogue receivers with the new technology. All have also decided that the analogue services will end finally, and that the spectrum being used for this purpose will be taken back from the broadcasters and used elsewhere.

     A difference of direction has emerged regarding the introduction of HDTV services, with the US and Japan seeing it as an integral part of the new digital platform, whereas the European model, claiming to be business driven, does not include it in the immediate future. Instead the Europeans have decided to provide "Digital Multiplexes" whereby several standard digital channels would be transmitted in the space of a single analogue channel. In some cases these digital channels would be offered to competing program providers making it difficult to recombine the channels for HDTV transmissions, should it be necessary some time in the future.

     Throughout the world, governments and broadcasters have become aware of the tremendous benefits that switching to digital broadcasting will bring and are now planning their moves in this direction. In this region there has been considerable activity, with Taiwan and Korea opting for the US system and Australia choosing the European DVB standard. China and Singapore have also been doing comprehensive testing and are expected to announce a choice of standard and their conversion timetables shortly.

In Hong Kong, TVB, ATV and Radio Association of Hong Kong joined together to organize seminars and demonstrations on various standards of digital terrestrial TV broadcasting.

Prospects in Hong Kong

       If local viewers are to benefit from the many advantages of this new technology and Hong Kong is to remain competitive, then it is vital that we do not delay but start planning our move immediately. Using other countries as a yardstick, the time for testing, choosing a suitable system and implementing it is 3 to 4 years. Even if the Government gives the green light to start testing immediately, the reality is that the viewers will not have digital pictures until at least 2002. Once again Hong Kong faces the prospect of being left behind in the technology race!

     HDTV should be part of the package, when digital terrestrial TV is introduced to Hong Kong. Hong Kong viewers have demonstrated in the past that they expect programs of the highest technical quality. The high penetration of laser disks, the proliferation of home theatre equipment and the array of wide screen receivers in the electronics stores amply evidence this fact. A counter viewpoint put forward by some administrators is that HDTV should not be considered at all and that the new digital bandwidth should be used to provide viewers with more channels. Indeed more channels are needed, but this is best done through satellite or cable where hundreds of channels can be easily transmitted with no spectrum penalties. Digital terrestrial broadcasting can support only a few additional channels at most and so is better used for "quality" rather than "quantity". Of course, this should not preclude the transmission of standard definition TV channels and multimedia services as part of the programming lineup. It is true that the initial cost of HDTV receivers will be high when compared to today's analogue receivers, but prices are expected to drop as the US and Japanese HDTV markets mature. Some of us can remember criticism of the cost of the first colour receivers compared to the then standard black and white equipment. Today colour receivers are the norm, are very cheap and black and white receivers have become extinct along with the dinosaurs. It should also be remembered that the "Colour Era" lasted for more than 30 years and that the new "Digital Era" should have a life of at least 20. This opportunity should be taken to "future proof" our technology decisions as much as possible, rather than to be swayed by short-term factors.

     The cost of conversion to digital technology for the broadcasters will be very high and will not generate significant additional revenue for many years. However, governments worldwide have recognized the national benefits of this technology and have assisted broadcasters with its introduction. This has taken the form of reduced fees and other concessions designed to help offset the large start up costs. It is hoped that the Hong Kong Government will adopt a similar view. By actively working together with the broadcasters, it has the chance to give the viewers a wide range of new high quality services, and of making Hong Kong a leader in digital broadcasting in the region.

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