System for protection against copying on magnetic tape...

Dynamic magnetic information storage or retrieval – General recording or reproducing – Recording-or erasing-prevention

Reexamination Certificate

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Details

C360S027000, C360S015000, C360S078020, C360S078030

Reexamination Certificate

active

06882490

ABSTRACT:
An audio or other program signal is modified to provide protection against copying on a magnetic tape recorder. The signal from a source (10) is amplified (16) and then subjected to Fourier analysis (11) to determine the signal amplitude in a plurality of subbands across the audible range. The subband containing the component of greatest magnitude is selected on an adaptive basis and applied to a stored psycho-sensorial model (12), which determines the maximum amplitude of interference which can be masked by the selected subband. An anti-copy signal is generated (14) by complex division of the desired interference by a stored representation of the response of a tape recorder (13).

REFERENCES:
patent: 4086634 (1978-04-01), Cook
patent: 4644422 (1987-02-01), Bedini
patent: 5161210 (1992-11-01), Druyvesteyn et al.
patent: 5394274 (1995-02-01), Kahn
patent: 5513260 (1996-04-01), Ryan
patent: 5822360 (1998-10-01), Lee et al.

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