What Is a Digital TV Decoder?

Digital TV set-top box is a cable TV conversion device. It is a conversion device that converts digital TV signals into analog signals. It decodes and restores digitally compressed image and sound signals to generate analog video and sound signals. And audio equipment to provide viewers with high-quality television programs. It has adopted a compatible approach and has continued to this day in China. At present, digital set-top boxes can be divided into three categories, one is digital TV set-top boxes that focus on shopping, one is digital TV set-top boxes that target young people, and one is a digital TV set-top box designed only for parents. . ^[1]

Digital TV set-top box

Digital TV set-top box is

In 2010, China's digital TV set-top box industry entered a boom cycle of market structure adjustment and in-depth development. 2010 was a year of rapid development of China's digital TV set-top boxes, and the industry market developed steadily. Data from the National Bureau of Statistics show that in 2010 there were 317 digital TV set-top box enterprises above designated size; total assets were 21.134 billion yuan; sales income was 21.448 billion yuan, a year-on-year increase of 30.65%; and total profits were 1.092 billion yuan.

In September 2010, the General Administration of Radio, Film and Television issued

Digital TV set-top box is a conversion device that converts digital TV signals into analog signals. Digital TV set-top boxes have become an embedded computing device with a complete real-time operating system and powerful CPU computing capabilities. They are used to coordinate and control various set-top boxes. Part of the hardware facilities, and provide easy-to-operate graphical user interface (Graphical User Interface, GUI), such as the enhanced television electronic program guide, to provide users with graphic presentations and background materials.

It is also a new type of home appliance that expands the function of the TV. It is responsible for converting various information (including TV programs) into a format that the TV can display on the screen. At the same time, the set-top box has the "fool computer" capability. In this way, through internal software functions and a slight two-way transformation of the network, it is easy to implement a variety of services such as Internet browsing, video on demand, home e-commerce, telephone communication, etc., which can be described as one network.

When the TV transitioned from black and white to color TV, a compatible approach was adopted. The PAL-D system has continued in China to this day. The transition from analog TV to high-definition digital TV is a leapfrog transition, and it can be said that it is not directly compatible. That is to say, all analog TVs cannot be used, so it is not realistic to do it in one step. Countries have adopted a transitional The method-digital set-top box, effectively avoids the interference and loss caused by the TV signal during transmission, and the quality of the signal received by the TV has been greatly improved. This is just a transition. Since the scan line of an analog TV has been determined, it has a considerable distance compared with high-definition digital TV.

High definition digital television

1.Signal input

2.Signal loop output

3. RCA (Shadow Video Interface)

4. YPbPr (component output)

5. S-VIDEO (S terminal interface)

6. SPDIF (Digital Audio)

7, USB2.0 (can connect external devices, such as: mobile hard disk, USB flash drive)

8, network interface (realize interaction, you click me to play)

9, HDMI (high-definition interface)

1.Mainboard

2. Power board

3.Front PCB with remote control and button control panel

4. Tuner

5.RF modulator RF

6, upgrade serial RS-232

7.Flash

8, audio and video output interface RCA,

Channel decoding, source decoding, modulation and coding of uplink data, embedded CPU, MPEG-2 decompression, set-top box software, display control and descrambling technologies are the main technologies of digital TV set-top boxes.

Digital TV set-top boxes will change our existing TV concept and will also provide a brand new consumer terminal for the Internet, and this consumer terminal will be more popular, convenient and attractive than any other terminal such as PC, mobile phone, and PDA. With the trial broadcast of cable digital TV in various places, the promotion of digital TV set-top boxes has made great progress compared with a few years ago, but digital set-top boxes have not been widely used in China. There are several reasons for this:

China's set-top boxes are developing rapidly. Because the set-top box industry's resource supply or product demand is undergoing a series of changes, this industry is gradually shifting from other countries or regions to China's production and manufacturing. China has become the world's largest set-top box manufacturing center. In 2007, China's STB market was dominated by wired STBs. Set-top box market shipments reached more than 65 million units, an increase of 41.3% compared to 2006. Among them, the domestic set-top box shipments exceeded 30 million units, an increase of 49.32% compared to 2006. The domestic market set-top box shipments exceeded the foreign market for the first time; the cable set-top box market exceeded 25 million units at the end of 2007, an increase from 2006 Nearly 60%. China's digital TV entered a booming period in 2008. In addition to the strong growth momentum of cable digital TV, terrestrial digital TV has also made a breakthrough development with the opportunity of the 2008 Olympic Games. In 2008, although affected by objective factors such as snow disasters, earthquakes, and the global financial crisis, China's set-top box market is still in a boom cycle.

According to the "Tenth Five-Year Plan" for radio, film, television and science and technology and the 2010 Vision Plan, China will fully realize digital broadcasting and television in 2010, and stop broadcasting analog radio and television in 2015. Undoubtedly, the popularity of digital TV programs has become an inevitable trend, and China's current "analog TV + set-top box" conversion form has brought huge business opportunities to the set-top box market.

It is reported that federal regulations managers have adopted new equipment standards in the eastern United States to accelerate the transition to higher-quality audio and video digital televisions.

The Federal Communications Commission (FCC) passed a 5-0 vote to pass equipment standards that allow digital television signals to be connected directly to the television without the need for a set-top box and additional cables. To watch pay TV, users insert a security card into their TV set provided by their cable service provider.

Manufacturers hope to market high-definition televisions with this plug-and-play technology. They said the Federal Communications Commission's decision will boost consumer demand and stimulate companies to increase production and further popularize the new TV.

Unlike traditional analog television, digital television signals use computer language, which has a clearer image and also has other potential properties, such as Internet access, video games, and multiple programs on the same channel. Digital signals can be transmitted via satellite, wired or wireless broadcast.

Digital TV systems can basically be divided into front-end hardware systems (including multiplexers, scramblers, modulators, digital TV set-top boxes), software systems (CAS, SMS, EPG, data broadcasting and a series of servers) Digital TV set-top box 3 parts.

Of the overall cost of digital TV conversion, the investment in set-top boxes accounts for an absolute share, reaching more than 90% of the entire investment. Due to the huge amount of funds involved, every move in the digital TV set-top box market can cause severe vibration to the overall digital TV conversion in the country.

The principle and structure of the set-top box are shown below,

The digital set-top box is not only a user terminal, but also a network terminal. It can enable analog TVs to switch from passive receiving analog TVs to interactive digital TVs (such as video on demand), and can access the Internet to enable users to enjoy the full range of TV, data, and language. Location information service. Some people think that the set-top box is used to bring the TV to the Internet, which is a misunderstanding. In fact, the digital set-top box was one of the members of the Broadband Integrated Information Network before the popularization of digital television. With the development of digital technology, multimedia technology and network technology, the built-in and overall cost of digital set-top boxes will be reduced, allowing most users to realize a variety of services such as entertainment and Internet access on ordinary analog televisions.

In short, the set-top box, as the iconic product of digital TV, has a broad space for development. With the development of digital TV applications, chip technology and software technology, the functions of STB will also become more and more powerful, which can provide more services for operators and users to meet the needs of different levels.

10 top crimes of digital TV:

The most uncomfortable: the speed of changing channels is slow, there is a "stagnation period" of a few seconds;

The most disturbing: the volume of each station is not uniform;

The most depressing: frequent "mosaic";

The most hateful: crashes become common;

The most exhilarating: the price has almost doubled, and the program is almost the same as in the past;

The most disappointed: high-definition programs into the moon;

The most annoying: the remote control opens the bow left and right;

The most retrogressive: the TV has become a monitor for the whole family to watch;

The most unreasonable: Set-top boxes of home appliances also monopolize monopoly;

The most overbearing: forced conversion, not giving consumers the right to choose.

1. According to different classifications of transmission media: Digital Terrestrial Television (DVB-T); Digital Cable Television (DVB-C) (including optical fiber, copper axis and a hybrid network "HFC"); Satellite Digital Television (DVB-S) ); IPTV set-top box IP-based TV broadcast services and so on ...

2. Classification according to definition: SD STB (Standard Definition); ST HD (High Definition);

Classification according to whether scrambling can be solved: Free set-top box FASTB (FTA = Free To Air) refers to a set-top box that can only receive free programs; conditional receiver set-top box CA STB, CA = conditional access; CI set-top box CI = Common Interface interface.

The working principle of the digital set-top box sharing machine: the encrypted signal is input through the input terminal, and the internal circuit is used to cancel the interference signal (scramble method encryption), and then output the normal signal through the output terminal. There is an external condition for whether the decryption circuit works, that is, the signal fed back by the TV's high frequency head. If this signal is not fed back to the set-top box, the descrambling circuit does not work, and the undecrypted signal is still output, so it cannot be viewed normally. But why can only one set-top box be connected to one TV? Can one set-top box connect multiple TVs?

First put the set-top box near the high-frequency head of one of the TVs so that it can be watched normally, and then use a splitter to branch the signal from the output to the other TV. One disadvantage of this approach is that the other TV can only receive 5 channels near the channel that TV 1 receives. Then use an AND circuit or 555 circuit to make an open multi-resonator, whose resonance frequency can cover the entire frequency band of cable television. Place this resonator next to the set-top box. Make the set-top box can receive the signal from the vibrator, and then use the splitter to branch out multiple TVs from the output of the set-top, so that all TVs can receive signals from all channels. Finally, a high-frequency transistor such as 9018 is used to make a high-frequency transmitting circuit, and the RF output is used to transmit again, as long as the transmitting power is small, so that the set-top box can receive it. Or use a coaxial video cable branch to access the input or output end, except for the outer shielded cable, leaving only the middle cable about 1 meter long, and wind this cable in the set-top box. Let the leaked signal be received by the set-top box. ^[2]

I. Maintenance after shutdown

The maintenance of the hard disk player, including wiping, dust removal, decontamination, charging maintenance, etc., must be turned off first, and maintenance operations must be performed after stopping use. It is best to disconnect from the computer and TV, and then clean and maintain to avoid electric shock, short circuit and other dangers. Some users like to wipe the hard disk player during the process of playing music and movies. This is not in compliance with maintenance requirements, and also contains various dangers, which should not be violated.

Keep the hard disk player away from magnetic fields

The main components of the hard disk player are magnetic media, so it must be kept away from magnetic fields, otherwise the hard disk will be magnetized and data will be lost. Common sources of magnetic fields are speakers, speakers, mobile phones, and so on.

Third, pay attention to the environment and conditions of use

Hard disk players should not be used at high temperatures. The high temperature will change the frequency of the crystal in the hard disk. It is generally not suitable to be used near the blast furnace, and it is not to be used in the hot place. If it is necessary to use it under high temperature conditions, it is necessary to add necessary cooling equipment to ensure that the hard disk does not fail due to overheating.

Fourth, pay attention to moisture, mildew and mildew

The hard disk player must be kept dry and clean. Once the hard disk in the hard disk player is wet, it will cause an internal short circuit, in some cases, data will be lost, and in other cases, the hard disk will be destroyed. and so. When using a hard disk player, pay special attention to keep away from water and humidity, prevent water droplets, and prevent mildew. It is best to place the hard disk player in a special protective case. This can prevent the erosion of sweat and prevent the player's casing from being scratched by hard objects.

Five, avoid strong vibration

Handle with care when relocating to avoid damaging the hard disk player. Be more careful during use to avoid severe vibration. According to the working principle of the hard disk player, the hard disk and flash memory work differently. When the hard disk is reading and writing, the magnetic head and the disk are in close contact. At this time, if the hard disk is subjected to strong vibration, the hard disk may be damaged. The hard disk is discarded. Therefore, we better not move the hard disk player in a violent sports environment. Carry and use the hard disk player to keep the environment stable. Usually, it is best to wear a silicone protective sleeve to the hard disk player. This sleeve can serve as a buffer. Protect your hard disk player from unexpected vibrations that can cause problems.

Six, use the battery properly

Hard disk players generally use large-capacity lithium batteries. For lithium batteries, frequent charging will reduce battery life. So in general, it is best to recharge when the battery is about to run out. If the battery can be removed, then it is recommended to buy multiple battery wheels. When using the first battery, charge the second battery and use it alternately. This also prevents the embarrassment of the player from being unusable when one battery is suddenly discharged Happening.