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

• Current Assignee: Clarion Co., Ltd. (Faurecia SA)
• Original Assignee: Clarion Co., Ltd. (Faurecia SA)
• Inventors: Tomizawa, Akimori
• Primary Examiner(s): Buczinski, Stephen C.
• Application Number:
  US06/014,237
• Time in Patent Office: 719 Days
• Field of Search: 358/122, 358/124, 358/84
• US Class Current: 380/232
• CPC Class Codes: H04N 7/163 by receiver means only

Abstract

A validation apparatus in a pay television system, including a code detector means for successively detecting a sequence of code signals, from an encoded composite TV signal, a key code circuit means having a key code so as to validate the sequence of code signals detected in 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 the first control signal, thereby assuming a first state and being reset by the second control signal, thereby assuming a second state and being toggled by the 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 in 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 TV 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.

Claims

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.

2. The validation apparatus as set forth in claim 1, wherein said feature detector means comprises a ternary counter including a first, a second and a third flip-flops, and an AND gate.