[Photo] DVB technology and its application in the field of broadcasting (on)-DVB, broadcasting, cable TV – HC Network broadcasting industry
Of: Lipan Lin Liu Rui The nature of broadcasting is changing. Brought about by the new digital television has created a free multipoint broadcasting business, a new concept, it is no longer a simple "TV." Interactive services have also emerged, viewers can use the telephone return channel transmission options to show center. Some Internet sites have also introduced some of the TV show. Broadcast, computer and network technologies are integrated. We hope that the quality of a certain transmission capacity of more digital television channels to create a major miracle, but the digital broadcasting also brought newer, more complex business. Complex business and application of digital devices has stimulated the increasing processing power and Internet service to provide great content and cross-cutting, and television to provide entertainment and information, the integration of a variety of traditional forms.
Technical description of a DVB Broadly, DVB (Digital VideoBroadcasting) technology refers to all types of data can be transmitted "data container" broadcast [1]. DVB simply by the "container" for the transmission of compressed images, sound or data to the receiver. DVB "service information" to play the title role of the container to ensure that the receiver knows how to decode. DVB data broadcasting system and other means of different key, the container can carry different data units independent of the timing information. Such as sound and image, if not also reach the receiver, the receiver can make the sound and video information in sync, which is different from traditional television facilities for the Department.
DVB mode has a strong adaptability. For example, a 38Mbit / s data container can support eight standard television (SDTV) channels, four enhanced television (EDTV) channel, or a high-definition digital television (HDTV) channels. Currently, DVB satellite communication system is mainly used to deliver double the SDTV programs and related voice and data. DVB is also used for data broadcasting services, such as access to the Internet.
MPEG-2 DVB standard was adopted for the audio and video information source coding, and will be a number of sources multiplexed data stream and the auxiliary information into a single data stream suitable for transmission. Therefore, DVB baseband processing in a number of parameters, fields and structures with the same definition MPEG-2.
DVB service, it is a source coding is based on MPEG-2 digital broadcast technology [2], this technique has three criteria:
1. DVB-S, which is used in satellite transponders, the bandwidth is 26MHZ? 72MHZ;
2. DVB-T, it is for terrestrial broadcasting;
3.DVB-C is mainly used in cable television. DVB-C Digital Video Broadcasting system signals typically QAM (quadrature amplitude and phase modulation) mode transmission.
MPEG-2 while taking into account the quality of the image and high compression ratio, from a code rate of 2MB / s in the VHS picture quality up to a code rate of 18MB / s high-definition television (HDTV). General MPEG-2 encoder can be selected by the user to a channel of the TV signal compressed to 2MB / s, 3MB / s, 4MB / s, 5MB / s, 6MB / s and 8MB / s and other digital signal. Actual observations show that the compressed 6MB / s and 8MB / s images with no image compression is basically not different, but the compression is 4MB / s for fast sports images, you can see the image of the defect. Thus, sports programs generally use the 5MB / s rate over the standard definition television (SDTV) with 4MB / s bit rate, while the ordinary television video programs are multi-use 2MB / s? 3MB / s bit rate.
MPEG-2 to simplify the system structure shown in Figure 1, this figure is the MPEG-2 video and audio signal processing data flow diagram. The simple process of work described as follows:
DVB-C set-top box hardware features of eight functional modules including Tuner, QAM demodulator, MPEG-2 demultiplexing, MPEG-2 decoding, video encoding, audio D / A, the user control interface . Figure 2 is a diagram of the composition of DVB set-top boxes.
Digitally compressed cable TV receivers (set-top box DVB-C) is the realization of the digital television signal transmission cables in the cable television reception of new technologies. Transmission of digital television signals with strong anti-interference, no transmission loss, convenient and reliable encryption, receive audio and video quality, etc. Set-top box can be opened up channels in the future, for the creation of high-speed Internet, cable television and other business basis.
DVB technologically advanced applications such as multimedia data broadcasting, Internet-air, interactive broadcasting and the combination of GPRS technology in mobile communications.
disposablemedicalsuppliers.com offers high quality suppliers and high quality products, such as ENT Medicals Disposables , Disposable Dental Impression Tray disposable medical suppliers factory, disposable medical suppliers exporter, disposable medical suppliers wholesaler, disposable medical suppliers distributor , china disposable medical suppliers companies for domestic and oversee buyer. To know more information, please visits http://www.disposablemedicalsuppliers.com/
Processing your request, Please wait....
