The achievements of modern digital technologies of last two decades are indeed profoundly impressive; they have lit many candles. The latest ICTs (Information and Communication Technologies) have completely changed our world outlook. The digital technologies are advancing at a fantastic rate; every new step opens up fresh vistas.
the hi-tech innovations of last quarter of 19th century have dramatically changed the way people watch the television. From black-and-white to color and from low-definition to high-definition, television had come a long way. The newest transformation is an introduction of DTV (Digital Television); outfitted with interactive services and superior video and audio visual quality features; digital television proffers viewers a more affluent television experience than ever before. The ones and zeros of digital technology started sweeping away of analogy system
on 1 of June, 1990, when General Instrument proposed an all-digital high DTV system; launching an era of digital television as different from present day analogue television as was the introduction of color from the 19th century mechanical scanning experiments of Baird and Compbell-Swinton.
Digital technology is more efficient means of broadcasting compare to analogue systems. As a natural result of recent technological progress, all electronic equipments and systems are going to be digital. They are more reliable and less susceptible to noise and interference. The quality of signal can be controlled by controlling the bits/symbol rate. The digital signals can be duplicated exactly. The latest data compression techniques allow a more efficient use of the precious bandwidth; which means either more services can be delivered in less space or a more realistic picture can be viewed. The digital technology is capable of transmitting at least four to ten digital services /channels of comparable “standard” quality with same bandwidth required for s single analogue channel.
The gaps between the scanning lines of DTV are smaller or even invisible, so visual information is 2-5 times more detailed than before. Digital technology enabled the transmission of pictures in wide screen format which makes it possible to fit both “square” (4:3 aspect ratios) and “widescreen” (16:9 aspect ratios) television displays. Full surrounding sound capabilities are obtained by MPEG and Dolby Digital audio compression techniques.
The DTV transmission can be done through all transmission platforms. The DTT (Digital Terrestrial Television) signals are broadcast through an upgraded network within UHF (Ultra High Frequency) band using COFMD (Coded Orthogonal Frequency Division Multiplexing) and 8-Level VSB (Vestigial Sideband) digital modulation schemes. The signals can be received through a normal television aerial and viewed either by using an IDTV (Integrated Digital Television) set or by traditional analogue television set equipped with an integrated digital tuner or set-top box
The D-SAT (Digital Satellite) television transmission applies the QPSK (Quadrature Phase Shift Keying) modulation technique to transmit signals. At consumer end signals can be received by a parabolic dish generally mounted on a building in the line of sight of respective satellite and can be viewed either by decoding using a set-top box or by a satellite compatible IDTV (Integrated Digital Television) set. As satellites cover a wide geographical area so many services are encrypted and only accessed by buying the viewing rights. Digital Cable Television services with QAM (Quadrature Amplitude Modulation) scheme are delivered through a physical network medium like fiber-optic cables. The signals are decoded using set-top box. The DTV technologies, widely perceived to be superior are taking the place of old analogue technology.
A lot debate and activates under way across the glob and different countries have set different time frame for this digital switchover.Although the necessary hardware and software for digital television reception has reached a mature state yet there is still room to improve. The true benefits can only be realized if both viewers and broadcasters are willing to invest in this new emerging technology. The trend of finding better and cheaper solutions will never end.