DVB-T: the COFDM-based system for terrestrial television

In early 1996, the European DVB Project finalized what is now called the “Common 2k/8k Specification”. This specification is another important corner-stone of digital video broadcasting in Europe and numerous other countries in the world. The terrestrial system, termed DVB-T, is based on the channel-coding algorithms the DVB Project had earlier devised for digital television on cable and satellite. The modulation scheme that is used for DVB-T is OFDM (orthogonal frequency division multiplexing), which has been assigned the name of COFDM in conjunction with the channel coding. Two variants are described, one employing 1705 individual carriers in an 8 MHz channel (“2k variant”), the other employing 6817 carriers (“8k variant”). For each of the variants four specific types of guard interval have been defined. Each individual carrier can be modulated either by QPSK, 16QAM, 64-QAM or hierarchical modulation