We are now confronted using a transition. However, what exactly does it really mean? Digital technology was present in TV and radio production twenty years back. Now it is the right time to execute it one of the final links toward viewers and listeners who depend on terrestrial reception, in transmitters. Digital television is a wide term. We must differentiate between digital creation (making of the program) and actual broadcasting – transmitting signals to our rooftop antennas. It will be possible to create TV program together with the newest digital technology and air it in analogue or to produce in the quaint way that is analog and broadcast it. Thus be cautious when you talk about digital television.
Take a look at this simple example, if you don’t know what’s the difference between digital and analog signals. You’ll be able to tell how big is your TV display in two different manners. If the size is shown by you with your hands then this is an analog value. The size of screen is represented with all the space between your left and right hand. This space can be arbitrary small as well as the value (in this case the space between hands or display size) can be any value between zero (both hands together) and the maximum span of your hands.
To tell the display size in digital you’ll quantify it with meter tape or ruler by rounding that number to some suitable variety of decimals and noticing the amount at the conclusion of screen. This amount now signifies the digital (numerical) value of the display size. Everything you’ve got done is actually an analogue to digital conversion. Now you have a number that represents the size of the screen. It’s not an exact value of the screen size but a value which is sufficient for many functions, as you’ve rounded the amount. To measure value that is precise it might require an endless variety of decimal places that is not possible to attain and generally we don’t need that precise amount.
Why are we switching to digital television broadcasting? The main reason is more powerful usage of the radiofrequency spectrum. The bandwidth of this channel is between 6 MHz (USA) and 8 MHz (Europe). The quantity of radiofrequency spectrum open to television broadcast medium is limited. So there’s a fixed quantity of stations (frequencies) that can be utilized for television broadcasting. If we are able to make certain that transmitters airing on the same frequency are far enough to avoid interference we can reuse these frequencies. Many countries have used all frequencies and additional growth of television stations with terrestrial broadcasting was impossible. A fresh technology needed to be developed. Sound and video signals are digital and may be effectively compressed with various compression approaches. Digital broadcasting can use one frequency station to broadcast a package of compressed television, data and radio services called multiplex.
Different digital standards have been created. ATSC is used in North America; DMB-T can be used in China; ISDB-T can be used in Japan while many other countries, Australia and Europe have decided to use DVB-T. All these standards carries a stream of digital data. This transport stream comprises compressed sound and video. There are two popular codecs or compression algorithms (standards) used for compression: MPEG-2 and the newer, better standard MPEG4. Every one of these standards are incompatible and you will need a digital receiver (set-top-box) which is harmonious with transmission and compression standards used in your nation.
