Research And Implementation Of Digital Television Front Of Conditional Access System

With the promotion of tri-networks integration and the bidirectional transfer ofdigital television networks, the tri-networks integration services have developed rapidly.The number of digital television users has achieved new breakthrough in scale, whichurges the broadcast television network operators to promote innovations in technologies,application and modes continuously and enrich video content and increase thevalue-added services, in order to meet the needs of different areas on material andculture. According to television programs and value-added services purchased by users,broadcast television network operators use conditional access system to authorize theend users and protect the users’ legitimate rights and interests of enjoying theircustomized or value-added services. As the core of the broadcast networks, conditionalaccess system plays an increasingly important role in the protection of interests ofBroadcast Television network operators and telecom operators. Thus broadcasttelevision network operators have increased demands on the security of basic andvalue-added broadcast services in the Next Generation Broadcasting network.The conditional access system in this paper is head-end component of cabletelevision network system, by which the Scrambler controlled to scramble the outputMPEG-2streams of the multiplexer, and then export to the cable television networkaccording to the authorization information based on the program users’ detriment andthe output of MPEG-2streams modulated by the QAM modulator. The main content ofthis paper as follows:First, study the common scrambling algorithms which are used to scramble anddescramble. Research on scrambling and descrambling MPEG-2stream has been doneunder the comprehension of the scrambling algorithms.Second, study the functions of each module of the DVB Simulcrypt head-endsystem architecture. This paper has discussed the communication messages on theinterfaces of Entitlement Control Message Generator, Entitlement ManagementMessage Generator and Event Information Scheduler.Then, the software architecture design and implementation of Entitlement Control Message Generator, Entitlement Management Message Generator and EventInformation Scheduler on Linux platform has been accomplished.Finally, the functions of the conditional access head-end system, which is consistof ECMG and EMMG and EIS have been tested.