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:
Sep. 27, 1994
Filed:
Sep. 14, 1992
Per Lindholm, Stockholm, SE;
Cominvest Research AB, Stockholm, SE;
Abstract
In a method and an apparatus for preventing external detection of the signal information in video signals occurring in, and being emitted from, video signal circuits in a display unit, or a similar unit, and including substantially consecutive frame or field signals, each constituted by substantially consecutive line signals, a phantom signal in the form of at least one pseudo-random bit signal sequence with properties similar to those of the video signals is emitted in addition to the video signals. A generator for generating the phantom signal is connected to an external power supply line to the unit containing the video signal circuits, for output of the phantom signal on this line. Using a control unit, the bit frequencies of the pseudo-random bit signal sequence/sequences are varied. Furthermore, the pseudo-random bit signal sequence/sequences are formed of a number of part signal sequences with a duration varying from one frame or field period to another.