How many TV transmitters principle do you know？

1.Principles of TV jets

After the TV's video and audio signals are digitized, the amount of data is very large, which is not conducive to transmission. Therefore, data compression technology becomes the key. There are two ways to implement data compression techniques:
1.1 compression encoding
The IEEE's MPEG expert group has developed and formulated the ISO / IEC13818 (MPEG-2) international standard. MPEG-2 uses different combinations of layers and levels to meet the quality of home-to-broadcast and high-definition television that will be broadcast. It has a wide range of applications for different requirements. It supports standard formats such as 16: 9 widescreen and high-definition television. This standard has been adopted for microwave transmission from home DVDs to satellite TVs and broadcast televisions.
1.2 Improved coding
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); digital Open-ground television systems (DVB-T) use more complex coded orthogonal frequency division modulation (COFDM).

2 Specific classification of digital TV
The principle of TV transmitter:
1) Signal transmission: According to the digital TV signal transmission, it can be divided into three categories: terrestrial wireless transmission (digital terrestrial television DVB-T), satellite transmission (digital satellite television DVB-S), and cable transmission (digital cable television DVB-C).
2) Product type: According to the product type of digital TV, it can be divided into digital TV display, digital TV set-top box, and integrated digital TV receiver.
3) Screen format: According to the display screen format of digital TV, it can be divided into two types: 4: 3 format ratio and 16: 9 format ratio.
4) Number of scanning lines: According to the number of scanning lines, digital TV can be divided into HDTV scanning lines (greater than 1000 lines) and SDTV scanning lines (600 to 800 lines).
5) Clarity: can be divided into low-definition digital television (image horizontal sharpness greater than 250 lines), standard-definition digital television (image horizontal sharpness greater than 500 lines), high-definition digital television (image horizontal sharpness greater than 800 lines) Line, ie HDTV). The image format of VCD belongs to the low-definition digital television (LDTV) level, and the image format of DVD belongs to the standard-definition digital television (SDTV) level.

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