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Validation apparatus in a pay television system

  • US 4,250,524 A
  • Filed: 02/22/1979
  • Issued: 02/10/1981
  • Est. Priority Date: 02/22/1979
  • Status: Expired due to Term
First Claim
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1. A validation apparatus in a pay television system for receiving an encoded composite T.V. signal which has been formed by adding a sequence of code signals as a first key code to a normal composite T.V. signal in a transmitting end, and validating the accurate corresponding relation between said first key code and a second key code which is preset in a receiving end, said apparatus comprising:

  • a code detector means for successively detecting from said encoded composite T.V. signal said sequence of code signals;

    a key code circuit means having said second key code so as to validate said sequence of code signals detected by said code detector means for generating a first, a second and a third control signals in response to said sequence of code signals;

    a polarity flip-flop means being set by said first control signal, thereby assuming a first state thereof being reset by said second control signal, thereby assuming a second state thereof, and being toggled by said third control signal, thereby changing from the first state to the second state or changing from the second state to the first state;

    a counter means for generating an output signal when the number of state changes in said flip-flop means reaches a predetermined value;

    a feature detector means for generating an output signal when the detector means receives said third control signal a predetermined number of times which is peculiar to said sequence of code signals; and

    a gating means for generating an output signal so as to generate a valid signal representing that said encoded composite T.V. signal is effectively decoded when both the output signal of said counter means and the output signal of the feature detector means are input thereto at the same time.

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