TABLE OF CONTENTS The transmission of television signals involves an analogue carrier waveform that is modulated by the video (and audio) information. While the carrier is analogue, the video information may be analogue (analogue television) or digital known as digital television (DTV). In analogue television, the totality of the composite video, blanking and sync is transmitted in its original analogue format. In DTV, the video and audio information are first converted into a digital format composed of a series of zeros and ones (bits). The series of bits is then used to modulate an analogue carrier before broadcasting via an aerial. At the receiving end, the digitised video and audio information is converted back to their original analogue formats for viewing and listening by the user.
Broadcasting a high volume of information requires a very wide bandwidth which for analogue television is between 5 and 6 MHz. For digital video broadcasting (DVB), a bandwidth of 10 or more times wider is necessary. For this reason, data compression techniques are used to reduce the bandwidth to manageable proportions. In fact, data compression is so effective that more than one programme is made to fit within the bandwidth allocated for a single analogue channel. This is just one advantage of DTV broadcasting. Here are some more:
Very good picture quality
Increased number of programmes mentioned above
Lower transmission power reduces adjacent channel interference
Lower signal-to-noise ratio
No ghosting
Broadcasting of DTV signals involves...
