1
Atsushi Nagata, Yutaka Uekawa, Takanori Senoo, Kenichi Takahashi: Method and apparatus for protection of signal copy. Matsushita Electric Industrial, Wenderoth Lind & Ponack, December 18, 1990: US04979210 (292 worldwide citation)

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 ...


2
Nagata Atsushi, Uekawa Yutaka, Senou Takanori, Takahashi Kenichi Enoki Cho: Method and apparatus for protection of signal copy.. Matsushita Electric, January 11, 1989: EP0298691-A2 (12 worldwide citation)

This invention relates to a method and apparatus for protection of signal copy for preventing unauthorized copy of music software such as record, compact disc and music tape by recording. More particularly, when manufacturing the music software, that is, when recording audio signals into the medium, ...