Cryptography – Cryptanalysis
Patent
1994-03-31
1995-09-12
Barron, Jr., Gilberto
Cryptography
Cryptanalysis
455 2, 348 1, H04L 900, H04H 900
Patent
active
054504902
ABSTRACT:
Apparatus and methods for including a code having at least one code frequency component in an audio signal are provided. The abilities of various frequency components in the audio signal to mask the code frequency component to human hearing are evaluated and based on these evaluations an amplitude is assigned to the code frequency component. Methods and apparatus for detecting a code in an encoded audio signal are also provided. A code frequency component in the encoded audio signal is detected based on an expected code amplitude or on a noise amplitude within a range of audio frequencies including the frequency of the code component.
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Graybill Robert B.
Hassan Sayed
Jensen James M.
Lynch Wendell D.
Sabin Wayne
Barron Jr. Gilberto
Flanagan, III Eugene L.
The Arbitron Company
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