Studying And Realizing For System Multiplexing Technology In The IPQAM

With the gradual growth of information needs of users, they have not satisfied the passive acceptance of one-way information but to want to participate in it. Interactive video will be the mainstream. With the emergence of new video transmission technologies and means such as live satellite television and network television, the monopoly advantages of traditional cable television network (HFC) no longer exist. Besides, the competition among major operators becomes fiercely in the field of video transmission. The IP network edge QAM-IPQAM discussed in this paper is just the key equipment for interactive services in the HFC network.The paper firstly analyses the network environment of IPQAM, introduces the relative protocols and carries out a detailed analysis of the requirements of IPQAM from the aspects of operation demand, function demand and performance demand and etc. According to the result of requirment analysis of IPQAM, the paper analyses the software structure and hardware structure of IPQAM. The design of IPQAM includes data-exchange module, main-controlling module, QAM-modulating module and up-frequency-conversion module. According to the demands for software environment, the paper uses embedded linux as real time operation system and builds the development environment for embedded linux, which lays the foundation for application software development.The paper focuses on the design of multiplex function of IPQAM. The demultiplexing of digital TV is separated into system demultiplexing and program demultiplexing. What the paper designs is system demultiplexing in the IPQAM, which turns several SPTS into MPTS. Meanwhile, the IPQAM achieves the search and reconstruction of PSI, emendation of PCR, re-mapping of PID and transport stream intertexture. The paper designs the above modules respectively. On the basis of analysing the principle of system multiplexing and PSI, the paper researches the key technology which includes the search and reconstruction of PSI and emendation of PCR. The paper designs the emendation of PCR in detail in QAM-modulating module because data-exchange module can not support 42 Counter. And a scheme for IPQAM multiplexing is proposed in the paper.At last, the paper completes the design of multiplex software for IPQAM. According to multiplex processing flow, the paper designs software of PSI processing including extraction and reconstruction of PSI and re-mapping of PID, accomplishes programming and proving and presents experimental results which show that the design scheme is correct. The design effect attains the expected intention.