Summary: Mobile TV on the current struggle between the three technologies - mobile TV, DMB, DVB-H-HC network broadcasting industry
"Anytime, anywhere TV", once a people's dream; now with the emergence of mobile TV services, it is becoming a reality. Behind in mobile TV, there are different techniques camp battle. These technologies will give us exactly what kind of viewing experience? They each in turn in the Chinese market out of what action?
Digital multimedia broadcasting technologies, the business space is becoming saturated broadcast media and weak revenue growth for telecom operators the opportunity to bring the integration, also brought new development opportunities. Integration of mobile TV as a symbol of the two major industrial operations, recently attracted wide attention.
So-called "mobile TV" service, is using the mobile terminal to provide users with video information services.
Mobile TV services in two ways: one is based on the mobile operator's cellular wireless networks, streaming media multicast; the other is the use of digital audio broadcasting spectrum for digital multimedia broadcasting (DMB), to achieve multicast. Which, DMB technology is divided into terrestrial DMB, and satellite DMB, 3G mobile streaming media technology with a common form of the three major mobile TV technologies.
Large terrestrial DMB system DMB, full name of the digital multimedia broadcasting (Digital MultimediaBroadcasting), is the Digital Audio Broadcasting DAB (Digital AudioBroadcasting) developed on the basis of. DAB is the second FM and AM radio broadcast after the third generation, is a digital audio signal, the digital state of various coding, modulation, transmission and other processing. As the digital signal processing carrying out a variety of only the "1" and "0" two states, transmission media, their characteristics, including noise, nonlinear distortion, not change the quality of digital signals, which have greatly changed the technology of traditional analog system operating environment, improve the system's overall technical performance.
DMB full advantage of the technological advantages of DAB (in reliable high-speed mobile environment receiving signals), the function will transfer a single audio information expanded data, text, graphics and video and other carriers. DMB will be digitized audio, video and data services of various signals in the digital state for compression, coding, modulation, transmission and other processing, can achieve high-quality transmission, high power efficiency, high spectral efficiency, while combines multimedia features, providing high capacity, high efficiency, reliability of data transmission. From DAB to DMB, means from the digital audio broadcasting to digital multimedia broadcasting beyond, so that any digital information can be a platform with a digital transmission system, the system can provide users, including audio, video, integrated audio-visual information, including services and entertainment.
DMB technology in accordance with the transmission channels can be divided into four categories: wire transfer, terrestrial microwave transmission delivery, satellite transmission and satellite transmission ground mixture. The four digital television source coding in the same way, all the multiplexing MPEG data packets, but because of their different transmission channels, their channel coding is also used different modulation. Cable transmission technology for fixed location receiver, such as family, do not have the features of mobile media, mobile TV services can not be applied. Transmission technology for mobile business is mainly terrestrial DMB and satellite DMB.
Ground wave DMB is the signal sent by the center console launch pad, then the signal amplified by the transmitter launch, the user directly to receive.
DMB technology as more links related to the standard system is relatively large and complex. Since the last century since the 90's, digital TV in the rapid development worldwide, resulting in three major technology-based standards for ground-wave transmission standard, namely the European standard DVB (DigitalVideo Broadcasting), the U.S. standard ATSC (Advanced Television SystemsCommittee ), the Japanese standard ISDB (Integrated Services DigitalBroadcasting):
European digital TV standard DVB: since 1995, gradually release the European digital television terrestrial broadcasting (DVB-T), digital TV satellite broadcasting (DVB-S), digital cable television broadcasting (DVB-C) standard. European digital TV first consideration is the satellite channel, using QPSK modulation, COFDM terrestrial digital TV using modulation, 8M bandwidth, cable digital TV with QAM modulation. DVB development organizations because of anticipated mobile communications and digital broadcasting network integration possibilities, so that in September 2002 proposal, the development of applicable standards for handheld devices, DVB-H (DVB-Handheld), and in January 2004 to develop out the basic framework of the specification, then in February into the validation and standardization of procedures. As the DVB-H rapid pace of development, whether on the subject of American standard or related technologies are also moving closer to it.
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