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. 23, 1996
Filed:
Jul. 27, 1994
Thomas F Martin, Richardson, TX (US);
General Instrument Corporation of Delaware, Hatboro, PA (US);
Abstract
Video signal scrambling and descrambling methods and apparatus for a subscription TV system are provided which are compatible with other equipment operating in accordance with pre-existing modes of signal scrambling and descrambling. Coded indicator signals generated in accordance with the invention are inserted into selected lines of video signals before they are scrambled by a previously installed scrambler located at a central office. The scrambled video signals, with indicator signals inserted, are then sent to all subscriber locations within the TV system. At new subscriber locations, descrambling receivers, in accordance with the present invention, detect and decode the indicator signals and in accordance with a new mode of operation properly descramble the video signals. At old subscriber locations, previously installed descrambling receivers ignore the indicator signals and descramble the video signals in accordance with pre-existing modes of operation.