Concepts of digital TV

DTV: digital television refers to the digital technology used to process, compress, encode, and store active images, sounds, and other signals, A television system for receiving and Playing videos. All aspects of the system, including the process from Studio program production, to processing, transmission, storage/transmission, to receiving, displaying, and so on, all adopt digital signals. Compared with traditional analog TVs, digital TVs have significant improvements in both image and sound quality. The definitions can be divided into sdtv (standard definition television) and HDTV (high definition television). The bit rates are about 4 megabits and 20 megabits, respectively.

What are the advantages and features of digital TV: (1) high definition and good audio effect. Because digital TV uses digital signals throughout the process, it is not affected by program editing, transmission, broadcasting and receiving. (2) high bandwidth utilization. The original PAL analog channel can play 4 to 8 SD Digital TVs. (3) good anti-interference performance. This solution solves the problem of flickering, ghosting, and brightening on analog TVs. It can achieve high-quality reception of urban buildings and receive clear digital TV programs on mobile carriers. (4) It facilitates the development of various integrated and interactive services (including Internet services) and facilitates the construction of an "three-in-one" information infrastructure. Data transmission and application enable the audience to run many interactive applications on digital TV receiving devices, such as electronic program guides (EPG), stock information, and games; in addition, new programs can be opened, such as video-on-demand (VOD) or quasi-Video-on-Demand (NVOD) (5) Program Encryption and processing applications.

What are the transmission media of Digital TVs? According to the different transmission media, it can be divided into: terrestrial digital TV, cable digital TV (including optical fiber, copper axis and hybrid network), satellite digital TV, etc. Digital TV is a complex system, which mainly includes the source compression part for sampling, quantization, and compression coding of signals in the studio, and the channel transmission part for stable and reliable transmission in the transmitting data room, and the reception and display of thousands of households. The international standard of the source part is mainly the MPEG-1, MPEG-2, MPEG-4 and other video and audio standards proposed by MPEG (activity image Expert Group. There are many standards in the channel part. According to the different transmission media, there are three types of satellite, cable and ground. Among them, the satellite standards are the DVB-S proposed by European DVB organization, and the cable mainly has DVB-C, ground transmission mainly relies on DVB-t.

Supplement:Currently, there is a digital TV set-top box sharing device on the market. How many TVs can share different programs with one set-top box? This is impossible. It is technically difficult. Even if the product is cracked, it is illegal. Local cable TV companies make various programs into transmission streams (that is, TS), and send them to the set-top box through disturbing. Ts contains many programs, that is, the channels we used to call, according to the channel you want to watch, the modem (tuner) in the set-top box is located from ts, and different sets have different PID codes when sending, after the program is differentiated, the program is handed over to the decoder chip to solve the audio and video streams, and then played to the TV through a connection line with the TV. Shared devices on the market or devices with different frequency division can only process decoded signals. That is to say, all TVs have only one channel, so they cannot be switched over. Besides, each set-top box must have a ca card.