Abstract: A method and apparatus are provided for preventing unauthorized recording of video programs on tape, in which the frame repetition frequency of the signals to be transmitted is changed in such a manner that, on the one hand, the operation of a television apparatus used for reproducing said signals will not be disturbed, but that, on the other hand, the cooperation between the driving means for the tape and the recording head displacement in the tape recording apparatus will be disturbed. The apparatus comprises an input stage (4) for digitalizing the video signals, a shift memory (5), an output stage (8) for converting the video signals to be used into analog form, an input control stage (6) for the memory (5) and an output control stage (7) for the memory (5). The control frequency of the input control stage (6) is adapted to the frame repetition frequency of the digitalized video signals to be stored in the memory (5).

Abstract: A method and an apparatus for modifying video signals in such a manner that, when recording said signals with a tape recording apparatus, the control of this apparatus is disturbed, which signals comprise image point signals grouped according to image lines and preceded, in each line, by a line synchronization pulse and a colour synchronization signal, the plurality of lines being combined to a frame preceded by a frame synchronization pulse, the image point signals being situated at one side, and the synchronization pulses at the other side of a zero level, in which additional pulses resembling line synchronization pulses having a deviating shape or situated in deviating points of a frame are added. In particular, in at least a part of the frames, in a number of last lines the normal line synchronization pulses are removed in arbitrary locations, and, instead thereof, additional pulses with a deviating shape, and in particular a shorter duration, are introduced.

Abstract: A video camera system provides automatic intensity control and includes an imaging system and an image transducing apparatus having an entry window which is image line scanned and on which images of pictures to be taken are formed by the imaging system. The image transducing apparatus transforms these images into electrical output signals which are converted by an amplitude to frequency converter into control signals of corresponding frequency.