| With the rapid development of digital TV technology, Conditional Access System is more and more important in the digital TV broadcasting. CA system is the key technology for TV service operators to launch the pay-TV business as well as all sorts of value-incremental business. It will bring large economic returns to the operators and provide customers with more and higher-quality services. Simulcrypt Technology and Multicrypt Technology are two kinds of scrambling/descrambling technologies in the CA system, and the latter is the direction of future CA system for its better performance in security and compatibility.Firstly, the dissertation compares Simulcrypt Technology with Multicrypt Technology after the introduction of some basic knowledge of CA system, and then analyses the communication protocol standard and the physical interface standard of Multicrypt Technology in detail. Secondly, based on STi5516 chip and OS20 embedded RTOS, the design methods of the software and hardware of Multicrypt Technology and the realization processes of the software are given. Finally, we test the functions of each part and give the results of our tests.In the software implementation of Multicrypt Technology, we adopt the layering architecture and partition the programs into three layers which are device driver, command interface protocol stack and the high level application from bottom to top. Three layers are related through API functions. Thus, the software can be implemented and managed easily, and the command interface protocol stack can be transplanted to other digital TV receiver platforms easily. Moreover, message driven mechanism, finite state machine theory, and the mechanisms of embedded RTOS such as task and message queue are adopted in the implementation of command interface protocol stack.At present, our work has been applied practically to the digital TV products. It can descramble different CA systems'programs such as those of NDS, Irdeto, NagraVision, NOVEL-TONGFANG and DTVIA. |
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