Digital terrestrial TV
The analogue television appeared the first. This is widely spread around the world. However, this type of diffusion is ageing and not very innovative.
For this reason analogue television is currently tending to disappear to give way to digital television.
Digital television is largely based on analogue television. The major changes concern the compression of audiovisual sources and the way in which audiovisual information is routed.
Digital television can use different broadcast modes :
• the satellite,
• cable, in major cities,
• the Internet, in particular thanks to the advent of ADSL 1,
• the traditional terrestrial radio channel
Terrestrial digital television relies on the terrestrial radio channel.
Currently in France TNT is being deployed since April 1, 2005.
Elsewhere in the world many countries already have their network of TNT. These include the United States, Japan, Germany, England...
ADSL (asymmetric digital subscriber line) : high data rate transmission mode.
The most advanced countries in terms of digital media transmission are currently testing the convergence between the digital television and mobile supply.
Japan for example or South Korea offer the possibility to watch TV on its mobile phone.