Digital television standards emerged in the early 1990s in America and Europe. Gradually, new broadcasting technologies began to be introduced in all developed countries. Television companies began to gradually abandon analog broadcasting. For some, the switchover process took a few years, while for others it happened very fast – in a couple of months. The bottom line is that digital television offers broader opportunities and functions and both consumers and broadcasters have noticed the benefits of this transition.
Benefits of implementation
Today you can connect digital TV in any locality. The providers’ capabilities are expanding every year, which allows them to offer consumers a service of high quality and at an affordable price. Let’s consider what benefits such a switchover provides to broadcasters:
The possibility of economical use of the frequency spectrum. Analog television allows you to broadcast just one channel on one frequency, while you can organize broadcasting of 6-10 digital channels in one 8 MHz band only.
No converters, because the broadcaster receives the signal in digital form and transmits it to the air in the same format.
Expansion of coverage and the emergence of mobile users. The transition to digital broadcasting in Europe and America was driven by the need to distribute the signal to moving objects – planes, trains, cars.
Digital TV users can appreciate such benefits:
Maximum picture clarity, sound quality, independence from external interference, a wide range of tones.
Reception of the signal through the mobile terminal.
Additional functions – TV program and others.
Broadcasting with subtitles and multilingual sound.
Five-channel sound broadcast through a digital channel.
Interactivity: participation in surveys, feedback to the broadcaster.
Broadcasting standards in the world
Today, digital television operates under three established standards. In America it is ATSC, in Japan it is ISDB and in Europe it is DVB. Each standard is based on MPEG-4 packet compression technology. Differences concern the ranges of frequencies used, signaling and modulation methods.
Modern digital television operates on the DVB principle. This data transmission standard is subdivided into several independent systems:
DVB-S satellite transmission system;
Cable digital television DBV-C;
DVB-T terrestrial systems;
Broadcasting standard for cell phones DVB-H.
The main advantages of a digital signal are high sound quality, unprecedented picture clarity and simplified work of broadcasters. These are not the only advantages, that’s why digital broadcasting became popular in both large cities and small towns. The principle is that in the studio signals of individual video programs are combined by a multiplexer and transformed into a single DVB-stream. If there are restrictions on watching of separate channels the stream is closed and further on it is modulated.
The subscriber’s TV receiver has a special antenna for demodulation of the received signal. If a subscriber has a right to watch this channel the stream opens and transforms into DVB-container with MPEG-4 format signal and additional elements. This technology allows to receive the maximum definition signal without external interferences.