Apparatus and methods for including codes in audio signals

• US 6,996,237 B2
• Filed: 07/12/2002
• Issued: 02/07/2006
• Est. Priority Date: 03/31/1994
• Status: Expired due to Fees

• Current Assignee: The Nielsen Company LLC (MOOD Media Corporation)
• Original Assignee: Arbitron Inc. (MOOD Media Corporation)
• Inventors: Graybill, Robert B., Lynch, Wendell D., Jensen, James M., Perelshteyn, Michael M., Sabin, Wayne, Hassan, Sayed
• Primary Examiner(s): Barroń, Jr., Gilberto
• Assistant Examiner(s): Lanier, Benjamin E.
• Application Number:
  US10/194,152
• Publication Number:
  US 20030081781A1
• Time in Patent Office: 1,306 Days
• Field of Search: 380/252, 380/253, 380/241, 380/275
• US Class Current: 380/252
• CPC Class Codes: H04H 20/14 for monitoring programmes
• CPC Class Codes: H04H 20/31 using in-band signals, e.g. subsonic or cue signal
• CPC Class Codes: H04H 60/13 Arrangements for device control affected by the broadcast information
• CPC Class Codes: H04H 60/17 on recording information
• CPC Class Codes: H04H 60/37 for identifying segments of broadcast information, e.g. scenes or extracting programme ID
• CPC Class Codes: H04H 60/40 for identifying broadcast time
• CPC Class Codes: H04H 60/44 for identifying broadcast stations
• CPC Class Codes: H04H 60/45 for identifying users
• CPC Class Codes: H04H 60/58 of audio determination or detection of speech characteristics in general G10L25/00; speech recognition in general G10L15/00
• CPC Class Codes: H04H 60/63 for services of sales data processing systems or methods specially adapted for electronic commerce G06Q30/00
• CPC Class Codes: H04H 60/66 for using the result on distributors' side
• CPC Class Codes: H04K 1/02 by adding a second signal to make the desired signal unintelligible
• CPC Class Codes: H04L 27/10 Frequency-modulated carrier systems, i.e. using frequency-shift keying H04L27/32 takes precedence
• CPC Class Codes: H04L 27/30 wherein each code element is represented by a combination of frequencies

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.

Claims

1. An apparatus for encoding an audio signal simultaneously with multiple symbols, comprising:

means for generating a plurality of code frequency component sets, each of the code frequency component sets representing a respectively different code symbol and comprising a plurality of first code frequency components, each of the first code frequency components differing in frequency from each other first code frequency component of each of the code frequency component sets; and

code inclusion means for combining the first frequency components of at least two of the code frequency component sets in the audio signal, so that the first frequency components of the at least two code frequency component sets are simultaneously present in the audio signal.

2. The apparatus of the claim 1, wherein each of the code frequency component sets consists of a respective plurality of the first code frequency components.

3. A method for encoding an audio signal, comprising:

generating a plurality of code frequency component sets, each of the code frequency component sets representing a respectively different code symbol and comprising a plurality of first code frequency components, each of the first code frequency components differing in frequency from each other first code frequency component of each of the code frequency component sets; and

combining the first frequency components of at least two of the code frequency component sets in the audio signal, so that the first frequency components of the at least two code frequency component sets are simultaneously present in the audio signal.

4. The method of the claim 3, wherein each of the code frequency component sets consists of a respective plurality of the first code frequency components.