HIGH  DEFINITION  TELEVISION

 

K.M.Paul

Former E-In-C; &  Acting D.G.; AIR

 

The merit of digital TV, compared to analog, primarily is in its enhancement of picture quality in terms of video noise & interference. When we talk of High Definition Television ( HDTV ), it also does the job of quality enhancement of the picture but in terms of higher picture resolution. In other words it provides more details of the picture content, which otherwise is missing in analog TV.

In HDTV more nos. of horizontal scanning lines are used to communicate more picture information. Larger no. of horizontal lines therefore increase the vertical resolution of the picture. Simulteneously each horizontal scanning line contains more no. of picture elements ( pixels ), in the optical-to-electrical trasducer inside the camera as well as in the electrical-to-optical trasducer on the TV screen. This higher no. of pixels per scanning line enhances the horizontal resolution of the picture. Since all these enhancements of resolution are done basically by increasing the picture information, the picture signal demands larger bandwidth. The aspect ratio of the TV screen  in HDTV is changed from 4:3 (in Standard Definition TV ) to 16:9 (in HDTV ). This enhancement in horizontal dimension w.r.t. vertical is done because of the fact that the human eye has capacity to capture larger angle in horizontal direction than vertical. As experimented , 16:9 screen gives a much better viewing at a specified viewing distance. This is basically what is HDTV.

HDTV being digital in nature can enhance the picture quality also in terms of video noise & interference. So HDTV enhances the picture quality in terms of  resolution, video noise & interference. Therefore HDTV is a total picture quality enhancer. A normal young human eye can read best the picture resolution &colour discrimination. This is a bio-technical quality & a marvellous gift of nature. It has been always the efforts of engineers and scientists to attain the perfection near to the nature and to overcome the shortcomings as imposed by the nature, in the system developed. This has been a continuous journey of mankind right from its birth in this planet.

Technological development and its adoption in the society are two totally uncorrelated issues. Development of new technology or innovation goes in its own speed. It goes with the unique aim to overcome the natural impediments and explore the technical solution to a problem. While doing so it hardly gives consideration to the socio-economic feasibility of its adoption. A technology may be highly sophisticated with lots of merits. But it is not necessary that the society will immediately accept it for adoption. The acceptance of a new broadcast technology depends on the commercial viability and hence on many parameters like;- Cost of transmission- Spectrum efficiency- Cost of reception (Receiver)- Cost of service- Ease of use-  Range of services & Richness & quality of prog. Content etc.   If the whole lot of above parameters match those of Standard definition TV (SDTV),or if the programme content is really special & exclusive, or if there is some attractive value addition to the main programme, then the HDTV makes a place. Otherwise only for enhancement of technical quality of picture, it may not be acceptable to the common masses in large scale. This market behaviour is true not only for HDTV but for any new technology. The market behaviour is totally different. It does not go with the excellence of technology but with some other factors.

DTT or Digital Terrestrial Transmission is another live example in India. DTT was introduced in four metro cities nearly six years back. Till date there is not a single DTT receiver in the market. Apart from the high cost of DTT receiver i.e. Integrated Receiver Decoder (IRD); the DTT transmissions duplicate the contents of other terrestrial analog /digital satellite TV channels instead of giving something new, something exclusive to the viewers. None of the DTT channels carry any Value Added Services (VAS) to attract the viewers. Under this condition, it is quite natural that no one will go for it only for the sake of enhancement of some technical quality. DTT is therefore serving the purpose of theoretical satisfaction of engineers that it has been introduced in the country six years back blocking huge capital, as well as the precious RF spectrum in the four metro cities.

       It is the high time that we take lesson from the fate of DTT in India & make careful strategy before the introduction of HDTV broadcasting. Introduction of HDTV without consideration to the parameters stated above will lead to the same fate as DTT. It will again only serve the ‘Techno-Political’ purpose. That means, it will make only engineers happy that HDTV has been started in India and will give the politicians an edge in cutting the red ribbon in the inaugural function. Its benefits will not reach the masses.

The new technology which has direct relation with public acceptance should always start with one pilot project with minimum investment. Here all types of field experiments should be conducted to probe the market reaction, take necessary corrective measures and gradually progress to reach the mass acceptance. No such new technology should be suddenly started in large scale, nor any revenue earning assurance should be given to the govt. Otherwise it may only amount to a dead investment like DTT.

   HDTV has many other much more useful applications other than broadcasting namely- Medical science; Cinematography; Printing technology etc. Govt. should make efforts to promote these applications seriously. That will prove to be extremely beneficial for socio-economic purposes.

   In broadcasting, use of HDTV can be kept limited to only programme production & programme distribution (Networking) for the time being. This will improve the finally broadcast TV picture quality at the same time the burden of HDTV transmission & reception will not come into play. But first of all a pilot experimental project of HDTV transmission is necessary to study the market for its further evolution.