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What is the working principle of the digital set-top box?

Release time:2018-1-5    Browse times:2330【Back】
Each module of the set-top box works in collaboration with the high speed access of Internet. The user first requests a URL by sending the command. In the process of using the PPP point - to - point protocol, the command eventually reaches the Internet business provider's modem shared rack. Then through the dynamic allocation method, the user gets the IP address used in this transaction and sends the request to Internet. When the content of Internet is found, it is then sent to the Internet business provider (ISP). Then the router of ISP is responsible for sending it to the cable TV network, and finally back to the user's set top box. In the CATV set-top box, the information content was intercepted. The set-top box is the task of completing a gateway between the TV and the cable network. Its task is to manage the communication traffic of IP. It has the ability to control users' access to the network. Once the IP package reaches the set-top box, the video signal is separated from the package, and the data is decoded, and then sent to the browser, ready to be displayed on the TV set.
Because Cable Modem requires users to configure a computer to surf the Internet, which affects the expansion of user level. The use of set-top boxes does not need a computer and a TV set is enough, so the market prospect of set top box may be good. The information users transition from enterprises to households, the network bandwidth transition from narrowband to broadband, users of network equipment from the PC machine to take the TV set-top box (STB) using the interface transition, the transition from Windows to the TV remote control button interface, the information content from the service for enterprises to transition to the life of the people, is the direction of development of network service the set-top box (STB) is obviously a big stage of the direction.
Digital TV set-top boxes receive digital TV programs, deal with data services and complete a variety of applications. All kinds of sources are encoded by two levels before entering the CATV network. The first level is the source coding of video and audio signals, and all the sources are encapsulated into transport streams. The second level is the channel coding for transmission. With the front-end, the DTV set top box first extracts channel coding signals from the transport layer, completes the channel demodulation, then restores the compressed source coding signals, recovers the original video and audio streams, and completes the reception and parsing of data services and applications.
The working process of the digital TV set-top box, digital TV set-top box to select a channel through the network interface module, and demodulation and channel decoding, the output of MPEG-2 multi program transport stream data, to de multiplexer, demultiplexer MPEG-2 transmission from a data flow program extraction in packaged audio visual basic flow (PES) the data, including set-top box video PES, PES audio and auxiliary data PES, a descrambling engine comprises a multiplexer, which can stream data on the scrambling layer and the PES layer in the transmission is descrambled, demultiplexer output as audio PES descrambling. The video PES is sent to the video decoder, and the MPEG-2 video data is extracted and decoded, and then output to the analog encoder, encoded into analog video signal, and then output through the video output circuit. The audio PES is sent to the audio decoder, the MPEG-2 audio data is extracted and decoded, the PCM audio data is output to the audio D/A converter, the audio D/A converter outputs the analog stereo audio signal, and is output through the audio output circuit.

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