14 Type of TV: The Variety of Television Transmission Network

Craig Norris on the modern broadcast facilites (TV Technology Asia Pacific, Volume 25 Issue 4, July/August 2007): The modern broadcast facility is becoming a complex beast indeed. It isn’t just the internal workings that are transforming into IT platforms as this author described. It’s the distribution networks as well outside the TV station that are evolving and replicating. The modern broadcast engineer is expected to keep up with all these developments.  Traditional Analog Free-to-Air Terrestrial TelevisionThis has been functional in the Asia Pacific region sice soon after World War II. It began in Japan in 1953, Thailand in 1955, Australia and Vietnam in 1956, Hongkong in 1957, China in 1958, Korea in 1961, Indonesia in 1962, and Singapore and Malaysia in 1963. The longevity of this broadcasting platform is admirable. It is unlikely that any future television delivery system will last as long as the fifty-odd years that the analog platform has been around so far.

The basic fuction of an analog television transmitter is to broadcast one video plus two audio tracks in a 7 or 8 megahertz RF channel in the VHF or UHF band. The vast majority of the world’s television viewers are still watching televion channels broadcast to them on this platform.

Digital Free-to-Air Terrestrial TelevisionThis is terrestrial television’s third transmission technology wave, after black & white in the 1950s and colour in the 1970s. Most of the Asia-Pasific countries are adopting DVB-T with the exceptions of Japan (ISDB-T), South Korea (ATSC) and China (DMB-T/H).

The US started digital terrestrial broadcasting in 1999, Australia in 2001, Japan in 2003, Taiwan in 2004, and South Korea in 2005. Hongkong will launch digital TV by the end of the year. and most South East Asian countries will follow in the coming one to three years. Some confusion still exists as to what constitutes a digital service. Besides the obvious fact of a digital modulation scheme for the airwave, which could be one of four different schemes (DVB-T, ATSC, ISDB-T or DMB-T/H), the content of the service is still optional in many countries. The choice exists in America for up to 18 picture formats. Australian broadcasters are using up to four different picture formats.

The basic function of a digital television transmitter is to broadcast at least one SD and one HD service in a 7 or 8 megahertz RF channel in the VHF or UHF band. The typical bandwithh achievable with MPEG-2 is about 19 Mbps.

Singapore has decided to use MPEG-4 on their DVB-T platform, allowing somewhat more than 19 Mbps per multiplex. It’s highly likely that other South East Asian nations will follow Singapore’s example in the adoption of MPEG-4.

Traditional Digital Satellite Television-UnencryptedMany of the world’s global television services are distributed unencrypted as part of a DVB-S MPEG-2 multiplex on satellite transpoders. Standard DVB-S Integrated Receiver Decoders (IRDs) can receive the services. An example is CCTV International broadcast from China.

Traditional Digital Satellite Television-EncryptedMost of the world’s largest pay TV operators are using an encrypted DVB-S platform to reach their subscribers. Examples are STAR in Hongkong, Astro in Malaysia, SkyPerfecTV in Japan, SkyLife in Korea, BskyB in the UK, as well as DirecTV and Echostar in the US. In some cases, the satellite service is redistributed by cable TV headends, and in others, the subscriber receives the service directly via their own receiving dish (Direct-To-Home, or DTH).

Traditional Analog Cable TelevisionThis will eventually be replaced by digital cable TV services, but in some countries, it will take a long time to upgrade the analog network in order to support digital transmission to all homes.

MMDS TelevisionThis is a fast and easy way to connect buildings without laying cables in the ground. However, the bandwidth is much less than cable, and therefore MMDS is often used as an interim network while the cable network is being rolled out.

Digital Cable TelevisionThe biggest competitor to terrestrial television in most countries.

Broadband Television (IPTV)Starting to get a foothold in some places, such as Hongkong, but still a long way from toppling cable TV as the dominant pay TV platform around the world. It is essentially the same as a cable TV, except that is uses a shared Telco switched broadband network rather than a dedicated private cable network.

Video Clip Viewing Over the InternetYouTube is the most well-known example. It has a particularly strong following from the youth market. The original video designed for TV set viewing should be re-authored for the smaller area of the viewing window.

Video Clip Download Over the InternetNot a large scale service at this time, but highly likely to increase in popularity.

Long Form Video Programme Download Over the InternetMostly used for ilegal copyright abuse at this time. Legitimate use of the peer-to-peer network technology is under consideration.

Video Clip Viewing Over a 3G Celluler Phone NetworkStill in its infancy. Quite limited by the capacity of the network. The original video designed for TV set viewing needs to be reauthored for the smaller area and different format, of the viewing screen.

Video Clip Download Over a 3G Celluler Phone NetworkAlso still in its infancy and limited by the capacity of the network. The original video designed for TV set viewing needs to be reauthored for the smaller area and different format, too.

Mobile Television to Handheld ReceiversThis is llikely to be the next big wave of consumer TV consumption. Based on a ‘one-to-many’ true broadcast rather than the one-to-one unicast model used in cell phone network. The biggest stumbling block is the cost of establishing a new transmitter network for DVB-H handheld reception. The existing tranmitter towers for normal non-mobile reception do not form an appropriate network for a service to handheld mobile receivers.