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:
May. 23, 1978
Filed:
Jan. 17, 1977
Richard E Herman, Monterey, CA (US);
Other;
Abstract
A system for securing a pay-TV channel by coherently moving the RF components of the channel (with or without an encoding signal) beyond the AFC holding range of commercially available tuners. The system is comprised of means for mixing the channel carrier with a signal that is varied beyond that AFC holding range at a low rate between approximately 0.75 Hz and 1000 Hz. For greater security, an amplitude-modulated encoding signal is injected at an IF frequency that is between the audio subcarrier and the video subcarrier. The encoding signal is preferably a multiple of the line scanning frequency in order to interfere with both video and audio components. For decoding, a converter with adequate AFC holding range at the receiver of a subscriber is coupled to the receiver by a sharply tuned filter which traps the injected encoding signal.