Enhanced scrambling method and system for TV signals
AssigneeZenith Electronics Corporation
InventorGary J. Sgrignoli
Life of this patent
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Abstract
A television signal transmission system includes a cable head-end having a scrambler for scrambling a television signal and a subscriber decoder having an unscrambler for unscrambling the television signal in response to data signals from the transmitter. The unscrambler in the receiver is operated to unscramble the scrambled signal for authorized subscribers and to further scramble the scrambled signal for unauthorized subscribers.
Claims8
A method of operating a television communication system including scrambling means at a transmitting station and unscrambling means at a receiving station comprising the steps of:
- transmitting a scrambled television signal and a data signal;
- receiving said scrambled television signal and said data signal and under control of said data signal, selectively;
- operating the unscrambling means at the receiving station for unscrambling said scrambled television signal;
- and
- operating the unscrambling means at the receiving station for further scrambling said scrambled television signal.
A televsion signal decoder comprising:
- means for receiving a scrambled television signal;
- means for receiving and processing a data signal for deriving first and second control signals;
- and
- unscrambling means, responsive to said first control signal, for unscrambling the received television signal and responsive to said second control signal, for further scrambling the received scrambled television signal.
In a television system of the type including scrambling means for generating a scrambled television signal at a transmitting station and unscrambling means at a receiving station for unscrambling the television signal and means for sending a data signal from said transmitting station to said receiving station for controlling operation of said unscrambling means to unscramble the scrambled television signal, the improvement comprising:
- means responsive to said data signal for controlling said unscrambling means to further scramble the scrambled television signal.
A method of operating a television communication system including scrambling means at a transmitting station and unscrambling means at a receiving station comprising the steps of:
- transmitting a scrambled television signal;
- receiving said scrambled television signal;
- operating the unscrambling means at an authorized receiving station for unscrambling said scrambled television signal;
- and
- operating the unscrambling means at an unauthorized receiving station for further scrambling said scrambled television signal.
Dependencies are inferred from the claim text.