2104701-A is referenced by 32 patents.

A system for preventing unauthorised recording of source material comprises putting onto a source signal, for example a gramophone recording, a coded signal and including in a tape recorder a detector circuit to mar or inhibit recording only of that source signal, the coded signal being such that it does not significantly detract from the source material quality when played through normal equipment. A detector 8 is activated by the coded signal on attempted recording (and/or on replay) and may inhibit an amplifier 5 or activate a spoiler oscillator 10 which adds a spoiling signal to the input through a mixer 6. The coded signal may be a discrete signal comprising a burst of fixed frequency and may be recorded in digital form (e.g., as an 8 bis code word).

Title
Method and apparatus for preventing unauthorised recording of source material (e.g. a gramophone recording)
Application Number
GB19810024048 19810806
Publication Number
2104701 (A)
Application Date
August 6, 1981
Publication Date
March 9, 1983
Inventor
King James Bertram
GB
Assignee
King James Bertram
IPC
G11B 27/28
H04N 05/913
G11B 27/28
G11B 20/00
H04N 05/913
G11B 27/28
G11B 20/00
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