digea

Welcome to the digital era!

Technology


Digital terrestrial television [DTTV or DTT] is regarded as the technological evolution of broadcast television and an advancement of analogue television. Unlike other platforms, such as satellite signal transmission that requires a dish or IPTV needing an internet connection, digital terrestrial television is emitted on land-based radiofrequencies. Practically, what this means is that, just like analogue TV, signal reception is achieved using a simple antenna [aerial]. The main difference however, is the process of multiplexing in digital television, which allows reception of multiple channels on a single frequency range [e.g. a UHF channel]. To put it simply, with DTT each frequency can be used for more than one simultaneous channel broadcasts along with their supplementary services such as the Electronic Program Guide [EPG].

In order for Greece to have a modern digital platform, a co-decision made by all involved bodies resulted in the selection of the DVB-T MPEG-4 or H.264 technology, which refers to the standard as well as the encoding protocol.

DVB-T is a standard for the reception of the television’s digital terrestrial signal. It uses the same UHF channels as analogue TV and the digital reception is achieved terrestrially using antennas [aerials].

Unlike analogue transmission, through digital retransmission the UHF channels may be used more efficiently, since more channels/programs can be broadcasted digitally on each frequency. The modulation method on this particular standard is COFDM [Coded Orthogonal Frequency Division Multiplex].

Digital television can be standard definition [SD] and even High Definition [HD], as long as it is supported. The digital providers [e.g. Digea] have the infrastructure to transmit high definition signals, however to do so the content they receive should be in HD. In other words, each content provider [TV station] should send its program to the digital service provider in High Definition.

Alternative standards are used around the world, such as ISDB-T in Japan [similar to DVB-T], a variation of this in most countries in South America, standards DMB-T/H in China, while North America replaced the analogue NTSC with ATSC.

On the other hand, MPEG-4 is the method of compressing digital audiovisual data. This technology is the basis for the advancement of digital television and is the most prevalent among European countries, while it has also been preferred in Australia, New Zealand, Colombia and several countries in Africa.

This particular encoding protocol has been chosen because:

  • It offers 40% better quality than the previous MPEG-2 encoding system [DVD quality].
  • It ensures that in the future broadcasting in High Definition is feasible. In Europe it is already a current development.