Label: descrambler IC card
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0 Preface
Most of the charges for cable TV in China use manual fees. At present, the problems existing in China's cable TV charging management are mainly reflected in: 1 The number of households entering the network does not match the users of the viewing. It has caused difficulties in financial statistics of TV stations. 2 The charging system is not perfect, the number of users is inaccurate, and there is no effective sanction for users who violate the rules, making the charging work more difficult. 3 The cost of viewing fees is too high and there is no guarantee that the charging work will be completed on time and accurately. Adding descrambling to cable TV program signals is an effective way to solve TV charges. The use of Ic for key license cooperation as a paid carrier has many advantages. The use of IC card charging management has also driven the management level of the entire cable TV station, and the improvement of office automation has positive significance for the development of China's cable TV industry.
1 descrambler control principle
In order to effectively support the operation of the scrambled TV system, the reliability of TV scrambling is very important, followed by the convenience of charge management, using Ic card technology, with high security, convenient and reliable charging. The descrambler is divided into two modules, a card reader module and a descrambling module. In the card reading module: first, the user pays the fee to the designated place first, and each user is provided with an IC card, and the IC card is input into the user's password through the card writer and the deadline for using the cable TV according to the amount paid. The user inserts the card into the card reader, reads the data in the card reader, verifies whether it is legal, and the password is correct or not. And compare the date, if there is no overdue, the signal to the descrambling module is allowed to work. If the descrambler is not allowed to work, the user receives only the scrambled TV signal, which cannot be properly viewed, effectively realized. Automatic control of cable TV signals (see Figure 1).
Figure 1 plus descrambling system and charge management system
2 IC card descrambler hardware design
The product of this design is very large due to the free configuration of the radio to the user. In order to reduce the economic burden of TV stations, the cost must be low. For the above reasons, the devices used are mainly the logic encryption card AT24CO1 produced by ATMEL and the small single-chip AT89C2051. The 89C2051 is a small single-chip microcomputer introduced by ATMEL. Appeared in the Chinese market in 1995. Its main feature is the use of Flash memory technology, which reduces manufacturing costs. Its software and hardware are fully compatible with McS 51, which can be quickly accepted by Chinese users. The electrical rewritability of its programs makes development and experiment comparison. easy. And the clock chip DS1302 produced by DallAs, the IC card socket is a standard socket. The alarm circuit is composed of a non-gate and a speaker. The resistors R1 and R2 are pull-up resistors, and the three-stage tube is used to control the power-on and power-off of the deck. When it is low, the triode is turned on and the card holder is powered on; otherwise, it is powered off (see Figure 2).
Figure 2 IC descrambler hardware schematic
3 IC card reader software flow chart design
In the main program: First, the implementation determines whether there is a card insertion, which is done by calling the defibrillation subroutine. In this program, it is not only possible to judge whether or not there is a card insertion, and if not, it enters the next electronic program and is in a waiting state. If there is, power up, reset the subroutine, and power on the IC card. And initialize the IC card, after reading, start to read the data in the card, there is the address specified by the microcontroller, this step is completed by reading the card subroutine. After completion, the MCU enters the interrupt to read the date data in the clock chip, which is also stored in the address specified by the MCU. After the reading data is completed, the data comparison program is started to determine whether it is legal and whether the user has the right to watch the cable TV. This step is the most critical. If the judgment is wrong, the alarm program will be signaled to inform the user. If it is legal, the MCU will then give a signal to the descrambling module, allowing it to work, descrambling the encrypted TV signal so that legitimate users can see the normal TV signal.
Figure 3 flow chart
4 Conclusion
Through the design analysis of the IC card reader, a more economical and reasonable design method is given. The system is simple in structure and has certain scalability. A prominent feature is low cost and a certain market development value. The popularity of multi-functional Ic cards in the future will enable an Ic card to be used as a home-controlled cable TV network license. It has extremely high security and is not complicated to implement. It has certain practical value for the development of broadcast TV.
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