Patent ID: 9264657
Filing Date: 2016-02-16
CPC Classification: H04N

Claim Text:
1. A method of altering a program signal to provide protection against copying on a program recording device, the method comprising: receiving the program signal, the signal being divided into frames each having a plurality of lines of information, each line of information comprising a horizontal blanking interval, and each frame having a vertical blanking interval that comprises synchronization pulses for synchronization of the program on the screen of a receiver; adding at least one pulse into the program signal during the horizontal blanking intervals of at least some of the lines that contain picture information and also adding at least one pulse into the vertical blanking interval of the program signal, wherein the at least one pulse added during the horizontal blanking interval is positioned to partially overlap a horizontal synchronization pulse in the horizontal blanking interval and has a magnitude that is greater than a maximum magnitude of the picture information; additionally adding a first modulation signal to vertical synchronization pulses of the program signal; wherein the pulses and the first modulation signal added to the program signal are cumulatively configured such that when the signal is copied by the recording device, interference is produced in the reproduction of the copied signal that is not visible in the reproduction of an uncopied program signal.