Image signal transmitting method, superimposed signal extracting method, image signal output apparatus, image signal receiving apparatus and image signal recording medium

摘要

The PN code generation controlling means 15 produces a PN code generation clock signal PNCLK to generate the PN code of one chip to one vertical section and supplies this clock signal to an SS duplication preventing control signal generating means 16. The SS duplication preventing control signal generating means 16 generates the PN code of one chip to one vertical section depending on the PN code generation clock signal PNCLK and executes the spectrum spread to the duplication preventing control signal S3 using this PN code to form the SS duplication preventing control signal S5. The SS duplication preventing control signal S5 is superimposed to the image signal and is then output. Thereby, elimination and deterioration of the additional information which has been spectrum spread and is then superimposed into the image signal can be prevented to surely provide the additional information superimposed to the image signal.