05450490 is referenced by 542 patents and cites 46 patents.

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.

Title
Apparatus and methods for including codes in audio signals and decoding
Application Number
8/221019
Publication Number
5450490
Application Date
March 31, 1994
Publication Date
September 12, 1995
Inventor
Wayne Sabin
Baldwin
MD, US
Wendell D Lynch
Silver Spring
MD, US
Sayed Hassan
Clarksville
MD, US
Robert B Graybill
Ellicott City
MD, US
James M Jensen
Columbia
MD, US
Agent
Eugene L Curtis Morris & Safford Flanagan III
Assignee
The Arbitron Company
MD, US
IPC
H04B 17/00
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