Weak current College】 【digital high-definition TV and high definition TV】.

<br> <br> 1, digital television is shooting, editing, production, broadcast, transmit, receive, and other TV signal broadcasting and receiving of the whole process is the use of digital technology on the TV. Digital high definition TV is a .digital television (DTV) standards in the most advanced one, referred to as HDTV (High Definition TV). <br> 2, digital TV and analog TV, the biggest difference is the digital TV image clear and stable, the signal coverage zone image .quality from signal transmission distance, the signal transmission throughout the outside noise interference will not affect the TV image. While the analog TV signal transmission over distance, the lower the image quality. In recent years, technology development strength strong enterprise started in video processing circuits .using digital signal processing technology, improves the performance of analog circuits, for example: the analog TV's row frequency field frequency increase, realization, deinterlacing and times field (100HZ) scans to eliminate flicker and improve image quality. But this same previously mentioned digital TV .on the working principle is completely different, the effect is still better than digital television a lot worse. For example: high definition TV show format 1920 × 1080i image pixel density of up to 135 film film image quality. Digital television is also available in a .wide range of clarity grade different image display format. Our high-definition display format as 1920 × 1080i/50HZ interlacing, and the United States in high-definition TV show format with 1920 × 1080i/60Hz interlaced, 1280 × 720P/60Hz deinterlace, .standard definition display format with 720 × 480P/60Hz deinterlace, these are the analog TV. <br> 3. digital TV must have network terminal display function. In digital TV all clarity grade different video data, audio, data, text data can be .consolidated in a system standard for digital television broadcasting programmes not only can transfer images, and can transmit text information. Thus the design in the digital television must take into account the text appear in various scan display format. How many TVs can compatible scanning display format .is the difference between digital high definition TV quality one of the main criteria. Because you can only display one or two image formats (single-frequency technology) or several image formats (dual band technology) of digital TV sets and displays dozens of image formats .(frequency conversion technology) of digital television, whether in the design and production level has a very big difference. Using single-frequency technology or dual band technology can only display several image formats of analogue TV to digital TV by scanning circuits can be achieved through .innovation, and the use of inverter technology can show dozens of image formats of digital television sets, with international high-definition TV development trend of new concepts, and analogue TV scan circuit is very different. From a technical point of view of development, using .single-frequency technology or dual band technology programme is not a true digital television, will be eliminated. Adopt frequency conversion technology, is the real digital TV. <br> 4, digital TV with a high-quality sound system, receive analog TV, .have high bass adjustment, left and right channels of balanced, surround sound, loudness control switches, and other functions. In areas with NICAM, the remote control is set to automatic status, then NICAM according to TV broadcasting of automatic identification has no NICAM. .<br> 5, standard-definition TV: in the dual-frequency machine (except 50Hz scans, plus 60Hz or 75Hz or 100Hz scan digital TV) receive analog TV signals on the basis of increased to receive AV digital HD signal feature colour TV. .It can use Y, Pr, Pb terminal or VGA interface receives deinterlace 720p and interlaced 1080i, different scanning frequency of digital high-definition signal. <br> 6. domestic digital TV development and planning: <br> ① 1989: HDTV was listed .into national key science and Technology Commission arrangement in 1985. <br> ② 1994: the State Council approved the strategy of development of HDTV. <br> ③ 1999: six ministries and national HDTV industry group, Beijing for HDTV broadcast. <br> .④ 2000: approval of Beijing, Shanghai and Shenzhen for terrestrial HDTV fax broadcast test. <br> ⑤ 2001: call for five DTV terrestrial broadcasting programmes and assessment tests. <br> ⑥ 2002: ratification in Beijing, Shanghai, Shenzhen, Chengdu, .Nanjing and other 13 cities cable DTV broadcast. <br> ⑦ August 2003: set-top box to adopt separation scheme and card. <br> ⑧ 2005: Wired Digital TV broadcast in 33 cities, user reach 3,000 million to launch direct broadcast satellite .digital TV; determine the terrestrial digital TV transmission standard; opening of 50-80 digital cable TV channel. <br> ⑨ 2008: development of digital terrestrial television. <br> ⑩ 2010: national basic realization of digital television. <br> ⑾ .2015: stop analog television broadcasting. <br>.