Method and apparatus for providing a copy-protected video signal

An apparatus to modify a program signal to provide protection against copying on a recording device, the apparatus comprising:

• an input for receiving a program signal divided into video frames, each video frame comprising lines of information and a vertical blanking region, each line of information comprising horizontal synchronization pulses and a horizontal blanking interval, and the vertical blanking region comprising vertical synchronization pulses for synchronizing the program on the screen of a receiver;
• an output for outputting a modified program signal;
• a first adder configured to add at least one pulse into the program signal during the horizontal blanking interval of at least some of the lines of information that contain picture information and also adding at least one pulse into the vertical blanking region 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 maximum magnitude that is greater than a maximum magnitude of the picture information;
• and
• a second adder configured to additional add a first modulation signal to the vertical synchronization pulses of the program signal;
• wherein the pulses and said first modulation signal added to the program signal are cumulatively sufficient such that when the modified program signal is copied by a recording device, interference is produced in the reproduction of the copied signal that is not visible in the reproduction of an uncopied program signal.