04979210 is referenced by 292 patents and cites 17 patents.

An apparatus for the protection of signal copy for prevention unauthorized copying of music software such as records, compact discs and music tape by recording is arranged such that when recording audio signals on a medium, certain supplemental information is added to the audio signal to be recorded, and in the process of copying by reproducing this medium, when the supplemental signal is detected in the reproduced signal, the copying action is stopped to protect it from being copied.

Title
Method and apparatus for protection of signal copy
Application Number
7/216495
Publication Number
4979210
Application Date
July 8, 1988
Publication Date
December 18, 1990
Inventor
Kenichi Takahashi
Kyoto
JP
Takanori Senoo
Hirakata
JP
Yutaka Uekawa
Ashiya
JP
Atsushi Nagata
Hirakata
JP
Agent
Wenderoth Lind & Ponack
Assignee
Matsushita Electric Industrial
JP
IPC
G11B 15/05
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