| 摘要 |
PROBLEM TO BE SOLVED: To make appropriately and efficiently performable superimposition and demodulation of an electronic watermark information by appropriately detecting a synchronizing signal at the time of embedding the electronic watermark information. SOLUTION: The peak of an input signal is detected by a trigger detecting part 11, and the section made to be a unit of the embedding process of the electronic watermark information is decided. The input signal is converted to a frequency spectrum signal in an MDCT (modified discrete cosine transformation) calculating part 12 by the MDCT, and a representative value showing the signal level of a specific frequency is calculated in a representative value calculating part 13. In an encode part 14, a carrier wave signal of the specified frequency is produced in a carrier wave producing part 15 and subjected to PSK(phase shift keying) modulation in a PSK modulation part 16 by the electronic watermark information and spectrum-spread in a PN spreading part 18 by random number data of PN group produced in a PN producing part 17, then the obtained modulation signal is amplitude-modulated in an amplitude modulating part 19 in accordance with the representative value obtained by the representative value calculating part 13. This modulation signal is superimposed to the input signal by an adding part 20 and recorded on the recording medium. |
