The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 20, 1993
Filed:
Apr. 09, 1991
Toyokazu Yanagimichi, Chigasaki, JP;
Harumasa Kajita, Fujisawa, JP;
Tetsuo Kariya, Fujisawa, JP;
Toshikazu Wakabayashi, Fujisawa, JP;
Ichiro Kawashima, Chigasaki, JP;
Satoshi Nakanami, Kamakura, JP;
Masami Tanaka, Yokohama, JP;
Matsushita Electric Industrial Co., Ltd., Osaka, JP;
Abstract
A key signal conversion device for use in a CATV television system in which more than one different scrambling process is performed, the conversion device receiving one of a scrambled high-frequency signal in a television system and a sound intermediate frequency signal in the television system, extracting a key signal for unscrambling the scrambling in the television system and adding the key signal to a nonscrambled television signal which is to be subsequently scrambled by a process other than a process used to scramble the received signal, the key signal conversion device including: a first detecting circuit, for receiving the one of a scrambled television signal and a sound intermediate frequency signal, and for detecting one of a synchronizing signal of the television signal and a synchronizing signal superimposed on the sound intermediate frequency signal; a gate circuit, for receiving the one of a scrambled television signal and a sound intermediate-frequency signal, and for extracting the key signal therefrom using the synchronizing signal detected by the first detecting circuit; a second detecting circuit, for receiving the nonscrambled television signal, and for detecting a synchronizing signal thereof; and an inserting circuit for superimposing the key signal on the nonscrambled television signal in a predetermined horizontal interval in the vertical blanking interval of the nonscrambled television signal by the gate circuit using the signal detected by the second detecting circuit.