| 摘要 |
PROBLEM TO BE SOLVED: To detect an electronic watermark signal, which is used as a system for protecting copyright without any fraudulent alteration or forgery. SOLUTION: The processor for a reproduced signal of digital data, where an electronic watermark signal is embedded, is provided with a function for monitoring the connection situation of the transmission line 350 of the reproduced signal and an electronic watermark signal detecting means 320. When it is detected that the connection is disconnected, error display is performed in a system control means 340, thereby detecting the fraudulent alteration or forgery.
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