The principle of digital TV

1 Working principle

After digitizing the video and audio signals of the TV, the amount of data is very large, which is very unfavorable for transmission, so data compression technology becomes the key. There are two ways to implement data compression techniques:

1.1 compression coding

The IEEE MPEG Expert Group has developed the ISO/IEC13818 (MPEG-2) international standard. MPEG-2 uses different layers and levels to meet the quality of the high-definition TV from the home quality to the broadcast quality. Different requirements, its application is very wide, it supports standard resolution 16:9 widescreen and high definition TV and other formats, from the entry of the family DVD to satellite TV, radio and television microwave transmission are adopted this standard.

1.2 Improved coding

Develop new digital modulation techniques to increase the data rate per unit bandwidth. For example, in the European DVB digital television system, the digital satellite television system (DVB-S) uses quadrature phase shift keying modulation (QPSK); the digital cable television system (DVB-C) uses quadrature amplitude modulation (QAM); The terrestrial open circuit television system (DVB-T) uses more complex coded Orthogonal Frequency Division Multiplexing (COFDM) modulation.