Literacy digital TV set-top box

Digital TV: A television system or television device that uses digital signals during processing, transmission, transmission, and receiving of television signals. A TV that can directly receive and process external digital TV signals is called a digital TV. A TV that receives analog TV signals and uses digital processing technology only in image restoration. It is often called "digital TV", but this is not a real digital TV. The specific transmission process of digital TV is:Digital TV signals are formed after digital compression and digital modulation by the images and sound signals sent by television stations, which are transmitted by satellite, Ground radio broadcast, or cable, after being received by a digital TV device, the original image and sound are restored through digital demodulation and digital audio decoding. Advantages of digital signals:Digital signals have much stronger anti-interference capabilities than analog signals. Digital Signals basically do not produce new noise during transmission. From the perspective of communication, frequency is a kind of resource, and the frequency band of RF is limited. Digital TV systems can use bandwidth more effectively than traditional analog TVs. At the same bandwidth, digital TVs can transmit programs several times as many as analog TVs, making it easier to spread high-definition programs with a large amount of data. Easy to store and process signals. It facilitates various integrated and interactive services. It is easy to implement encryption, decryption, and disturbing/disturbing technology, especially for various billing services. From the operator's perspective, we can better control users and change the overall business philosophy and methods.
DVB-S digital satellite live broadcast system standards:The digital satellite transmission system is designed to meet the bandwidth of the satellite forwarder and the transmission characteristics of satellite signals. After the publication of the DVB-S standard, almost all satellite live video digital TV adopts this standard, and our country also chooses the DVB-S standard. DVB-T Digital Terrestrial Broadcast System Standards:The standard of this system was passed in 1998, which is the most complex DVB transmission system. The Code orthogonal frequency division multiplexing (coofdm) modulation method can transmit four TV programs at 8 MHz bandwidth, and the transmission quality is high. MPEG-2 digital video, audio compression encoding technology. DVB-C digital cable broadcast system standards:This standard uses a cable TV network as the transmission medium and has a wide range of applications. DVB-C transmission system has the following main characteristics, and can adapt to a variety of program source. The program transmitted by the DVB-C transmission system can be from the Program received by the satellite system, also can be from the local television program, and other external program signal; standard digital TV and HDTV. Set-top boxIn a broad sense, any network terminal device connected to a TV can be called a set-top box. Including analog and digital set-top boxes. In a narrow sense, it is the set-top box that we will constantly mention in this article, that is, the digital set-top box in the current analog TV to digital TV. Signals can come from Wired cables, satellite antennas, broadband networks, and ground broadcasts. In addition to the images and sounds provided by analog TVs, the content received includes electronic program guides, Internet webpages, subtitles, and so on. Set-top box classification: based on different types of transmission media: Terrestrial Digital Television (DVB-T) Cable Digital Television (DVB-C) (including optical fiber, copper axis and two mixed network "HFCs ") television Broadcasting Service Based on IP protocol on Satellite Digital TV (DVB-S) IPTV set-top box
The abbreviation of DVB-digital video broadcasting digital video broadcast (HFCs) is hybrid fiber-coaxial. It is a hybrid network IPTV (Internet Protocol Television) that combines optical fiber and coaxial cable according to definition classification:
Standard definition digital TV set-top box SD STB (standard definition)
High Definition Digital TV set-top box HD STB (high definition) is classified based on whether the disturbance can be solved:
Free set-top box fta stb (FTA = free to air) refers to a set-top box that can receive free programs only
Conditional receiving set-top box ca STB (CA = Conditional Access) condition acquisition
CI set-top box CI = common interface Set-top box schematic:
Principle process: the antenna receives the satellite signal and uses the high-frequency head to reduce the frequency amplification to form the intermediate frequency signal. tuner locks the intermediate frequency signal, performs digital-analog conversion, calls out the analog signal, and uses the system to demultiplexing, split the TS stream and TS Stream compressed video packages, decompress and decode the audio and video separately, and obtain the program and send it to the TV. From the hardware point of view, the most basic set-top box generally has the following components: the main chip (CPU), flash (flash), memory (SDRAM, DDR), tuner (tuner), smart card interface, and audio and video output. The software in the set-top box can be divided into three main layers: application layer, intermediate interpretation layer and driver layer. Each layer contains many programs or interfaces. OSD:On-screen-display, similar to the user interface. CA:Conditional acess, a key decoding card dedicated to solving encrypted programs. Timer:Timer, set the time and the corresponding action, and the time will occur. RCU:Remote Control Unit, remote control. EPG:Electronic Program Guide, an electronic program guide, as long as it is a program forecast for a channel in different time periods. Scart:Syndicat des constructeursd 'appareils radior é cepteurs et t é l é viseurs, an audio and video output interface developed by peritel, a French company, to interconnect audio and video equipment with industrial standards, it is also the interconnection interface required by Europe for Satellite TV receivers, televisions, video recorders and other audio and video devices. The standard scart interface is a 21-pin connector with a right-angle trapezoid shape, commonly known as the "Broom head ".