High security pay television system
First Claim
1. A pay television broadcast system comprisinga broadcast station for distribution of programs in live and recorded formats including (1) scrambling means for imposing a scrambling signal on the program signal to create a scrambled broadcast signal, the scrambling signal being the inverse of a signal generated from a pre-selected changeable code, and (2) an encoder to imbed a broadcast code in the broadcast signal, the changeable codes being different for the live and the recorded formats so that the code for live formats broadcasts can be changed more often than the code for the recorded format;
- an alterable, reusable memory module for each viewing station carrying the changeable codes thereon;
a receiving station decoder for each receiving station including (1) means for one of the changeable codes from a removable memory module inserted in that decoder, the changeable code being selected to match the program type to be viewed, (2) means for imposing a descrambling signal complementary to the scrambling signal on the received broadcast signal, the descrambling being generated from the changeable code, and (3) writing means for writing information derived from the broadcast code on the memory module, the information indicating whether the broadcast viewed was recorded or live; and
the memory module having pre-written into it information which can be recognized by the receiving station decoder to limit the extent of program descrambling which can occur in the receiving station decoder.
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Accused Products
Abstract
A high security pay television system is provided in which subscribers are provided with a decoder and with periodically changed removable memory modules. The decoder only functions to properly descramble the scrambled broadcast signal when a changeable system-wide code is available in the decoder. The code can either be carried in the memory module, or an internal code unique to the decoder and resident in the decoder can be combined with a external code in the removable memory module, and also unique to that decoder, to generate the common systemwide system code. Program viewership is written on the removable memory module. The removable memory module is provided with a pre-written limit of program viewing authorization so that when the limit is reached, further viewing is not possible.
154 Citations
23 Claims
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1. A pay television broadcast system comprising
a broadcast station for distribution of programs in live and recorded formats including (1) scrambling means for imposing a scrambling signal on the program signal to create a scrambled broadcast signal, the scrambling signal being the inverse of a signal generated from a pre-selected changeable code, and (2) an encoder to imbed a broadcast code in the broadcast signal, the changeable codes being different for the live and the recorded formats so that the code for live formats broadcasts can be changed more often than the code for the recorded format; -
an alterable, reusable memory module for each viewing station carrying the changeable codes thereon; a receiving station decoder for each receiving station including (1) means for one of the changeable codes from a removable memory module inserted in that decoder, the changeable code being selected to match the program type to be viewed, (2) means for imposing a descrambling signal complementary to the scrambling signal on the received broadcast signal, the descrambling being generated from the changeable code, and (3) writing means for writing information derived from the broadcast code on the memory module, the information indicating whether the broadcast viewed was recorded or live; and the memory module having pre-written into it information which can be recognized by the receiving station decoder to limit the extent of program descrambling which can occur in the receiving station decoder. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. In a pay television system, a receiving station signal decoder for a scrambled broadcast signal also containing a broadcast code comprising:
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a microprocessor; a demodulator to derive the broadcast code from the broadcast signal; an electrically alterable memory module containing at least two pre-written external codes which can be used to generate a systemwide system code, one code used for time-independent programming and one code used for time-dependent programming, and also a portion onto which program information may be entered being pre-written with information to limit the amount of programming which may be descrambled; means for generating a descrambling signal complementary to the scrambling signal upon input of a proper numerical sequence; and the microprocessor programmed by a program (1) to read one of the external codes from the memory module, the external code selected being appropriate for the program being broadcast, (2) to operate on the external code to generate the systemwide system code, (3) to generate and output to the descrambling signal generating means a numerical signal generated from the system code, (4) to receive the broadcast from the demodulator (5) to read the information in the memory module as to the limit on the amount of programming which may be viewed and to determine if that limit has been reached, and (6) to write information about the programs actually descrambled, as determined from the broadcast code, in the memory module if the limit has not been reached, so that use of the decoder can be limited by the information pre-written in the memory module. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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Specification