Method and apparatus for encoding/decoding broadcast or recorded segments and monitoring audience exposure thereto

• US 5,579,124 A
• Filed: 02/28/1995
• Issued: 11/26/1996
• Est. Priority Date: 11/16/1992
• Status: Expired due to Term

• Current Assignee: The Nielsen Company LLC (MOOD Media Corporation)
• Original Assignee: Arbitron Inc. (MOOD Media Corporation)
• Inventors: Aijala, Victor A., Urbi, Juan C., Lynch, Wendell D., Jensen, James M., Cohen, Gerald B.
• Primary Examiner(s): Tran, Thai Q.
• Assistant Examiner(s): Chevalier, Robert
• Application Number:
  US08/396,342
• Time in Patent Office: 637 Days
• Field of Search: 381/14, 381/2, 381/3, 381/4, 455/2, 455/49.1, 455/53, 455/67, 358/335, 358/341, 358/343, 348/1, 348/2, 348/3, 348/5
• US Class Current: 386/201
• CPC Class Codes: C08L 2666/02 Organic macromolecular compounds, natural resins, waxes or and bituminous materials
• CPC Class Codes: C08L 91/00 Compositions of oils, fats or waxes; Compositions of derivatives thereof
• CPC Class Codes: C09J 133/06 of esters containing only carbon, hydrogen and oxygen, the oxygen atom being present only as part of the carboxyl radical
• 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 60/31 Arrangements for monitoring the use made of the broadcast services
• CPC Class Codes: H04H 60/372 Programme
• CPC Class Codes: H04H 60/375 Commercial
• CPC Class Codes: H04H 60/40 for identifying broadcast time
• CPC Class Codes: H04H 60/43 for identifying broadcast channels
• CPC Class Codes: H04H 60/44 for identifying broadcast stations
• CPC Class Codes: H04H 60/94 Telephonic networks for accessing the Internet H04H60/84
• CPC Class Codes: H04L 27/0004 using wavelets

Abstract

Methods and apparatus for encoding and decoding information in broadcast or recorded segment signals are described. In certain embodiments, an audience monitoring system encodes identification information in the audio signal portion of a broadcast or recorded segment using spread spectrum encoding. A personal monitoring device receives an acoustically reproduced version of the broadcast or recorded signal via a microphone, decodes the identification information from the audio signal portion despite significant ambient noise, and stores this information, automatically providing a diary for the audience member which is later uploaded to a centralized facility. A separate monitoring device decodes additional information from the broadcast signal, which is matched with the audience diary information at the central facility. This monitor may simultaneously send data to the centralized facility using a dial-up telephone line, and receive data from the centralized facility through a signal encoded using a spread spectrum technique and modulated with a broadcast signal from a third-party.

Claims

1. A method for detecting encoded information in broadcast or recorded audio signals, comprising the steps of:

receiving an encoded broadcast or recorded segment signal including an audio signal portion having an encoded identification signal, the encoded identification signal being produced by modulating a first code signal having a predetermined nonzero bandwidth and not derived from the audio signal portion with an identification signal having a narrower bandwidth than the predetermined nonzero bandwidth of the first code signal, correlating the audio signal portion with a second code signal corresponding to the first code signal and not derived from the audio signal portion to produce a correlated signal, and recovering the identification signal from the correlated signal.

2. A method according to claim 1, further comprising the step of synchronizing the second code signal with the encoded identification signal before the step of correlating.

3. A method according to claim 1, further including the step of transforming the audio signal portion to frequency domain information.

4. A method according to claim 1, wherein the step of correlating comprises multiplying the audio signal portion with the second code signal to produce a multiplied signal and wherein the step of recovering comprises integrating the multiplied signal.

5. A method according to claim 1, further comprising the step of frequency synthesizing in accordance with code data to produce the second code signal.

6. A method according to claim 5, wherein the step of correlating comprises mixing the audio signal portion with the second code signal.

7. A method according to claim 1, further comprising the step of storing the recovered identification signal as stored data.

8. A method according to claim 7, wherein the steps of receiving, correlating and storing are performed at each of a plurality of sites, and further comprising the step of sending stored data from the plurality of sites to a centralized data processing facility.

9. A method according to claim 1, further comprising the step of recovering additional information identifying at least one of station, channel and segment identity from the received encoded broadcast or recorded segment signal.

10. A method according to claim 9, further comprising the step of storing the recovered identification signal with the additional information.

11. A method according to claim 9, wherein the received encoded broadcast or recorded segment signal includes the additional information in the audio signal portion.

12. A method according to claim 11, wherein the received encoded broadcast or recorded segment signal includes the additional information substantially in audio signal frequencies above 3000 Hz.

13. A method according to claim 1, further comprising the steps of receiving a further broadcast including encoded broadcast data, the encoded broadcast data being produced by modulating a third code signal with a selected bandwidth by a broadcast data signal having a narrower bandwidth than the selected bandwidth;

and correlating the further broadcast with a fourth code signal corresponding to the third code signal to recover the broadcast data signal.

14. A method according to claim 1, wherein the step of receiving the audio signal portion comprises receiving the audio signal portion from a device carried on the person of an audience member.

85. A method according to claim 13, wherein the further broadcast is an FM broadcast.

87. A method according to claim 14, further comprising the step of supplying the audio signal portion to a means for converting the audio signal portion into an acoustic signal for use by the audience member.

89. A method according to claim 1, further comprising the step of sensing recording of the encoded broadcast segment signal by a recording means.

15. A method for detecting encoded information in broadcast or recorded audio signals, comprising the steps of:

transducing an acoustically reproduced audio signal portion of an encoded broadcast or recorded segment signal to produce a transduced audio signal portion, the audio signal portion having an encoded identification signal produced by modulating a first code signal having a predetermined nonzero bandwidth and not derived from the audio signal portion with an identification signal having a narrower bandwidth than the predetermined nonzero bandwidth, the encoded identification signal being imperceptible as information in the acoustically reproduced audio signal portion, correlating the transduced audio signal portion with a second code signal corresponding to the first code signal and not derived from the audio signal portion to produce a correlated signal, and recovering the identification signal from the correlated signal.

16. A method to claim 15, further comprising the step of determining an identity of an audience member within audible range of the acoustically reproduced audio signal portion.

17. A method according to claim 16, wherein the step of transducing comprises transducing an acoustically reproduced audio signal portion of an encoded broadcast wherein the audio signal portion is encoded with an identification signal including information identifying a source of the encoded broadcast, and further comprising the step of transmitting the information identifying the source and information indicating the identity of the audience member to a centralized data processing facility for producing an estimate of the audience for the encoded broadcast.

18. A method according to claim 16, wherein the identification signal identifies a source of the encoded broadcast or recorded segment signal.

19. A method according to claim 18, further comprising the step of assembling the identity of the audience member and the source of the encoded broadcast or recorded segment signal with a designation of the identity of the encoded broadcast or recorded segment signal.

20. A method according to claim 16, wherein the identification signal identifies one of a source of the encoded broadcast or recorded segment signal and a designation of the identity of the encoded broadcast or recorded segment signal, and further comprising the step of assembling data associating the identity of the audience member with the one of a source of the encoded broadcast or recorded segment signal and a designation of the identity of the encoded broadcast or recorded segment signal.

21. A method according to claim 16, wherein the steps of transducing and correlating occur within a device carried on the person of the audience member.

22. A method according to claim 16, wherein the step of transducing occurs within a first device carried on the person of the audience member, and the step of correlating occurs within a second device, and further comprising a step of wirelessly transmitting the audio signal portion from the first device to the second device.

23. A method according to claim 16, further comprising the step of storing the recovered identification signal with a timestamp as stored data.

24. A method according to claim 16, wherein the step of correlating is limited to only a predetermined audience survey time period.

25. A method according to claim 24, wherein the step of correlating is limited to the predetermined audience survey time period based on the second code signal.

26. A method for determining a source or sources of at least one copyrighted work included in broadcast or recorded audio signals, comprising the steps of:

receiving an encoded broadcast or recorded segment signal including at least one copyrighted work, the at least one copyrighted work including an audio signal portion having an encoded identification signal indicating a source of the at least one copyrighted work, the encoded identification signal being produced by modulating a first code signal having a predetermined nonzero bandwidth and not derived from the audio signal portion with an identification signal having a narrower bandwidth than the predetermined nonzero bandwidth, correlating the audio signal portion with a second code signal corresponding to the first code signal and not derived from the audio signal portion to produce a correlated signal, recovering the identification signal from the correlated signal, and assembling data representing the source or sources of the at least one copyrighted work.

27. A method according to claim 26, further comprising the step of recovering additional information indicating at least one of station, channel and identity of the at least one copyrighted work from the received encoded broadcast or recorded segment signal.

28. A method according to claim 27, wherein the identification signal identifies at least one of the station and the channel of the at least one copyrighted work, and the additional information indicates at least the identity of the at least one copyrighted work.

91. A method according to claim 26, wherein the steps of receiving and correlating are performed at a plurality of sites, and further comprising the step of analyzing the recovered identification signals from the plurality of sites and the assembled data representing the source or sources of the at least one copyrighted work to detect unauthorized copying.

29. A method for determining a source or sources of at least one commercial advertisement in broadcast or recorded audio signals, comprising the steps of:

receiving an encoded broadcast or recorded segment signal including at least one commercial advertisement, the at least one commercial advertisement including an audio signal portion having an encoded identification signal indicating a source of the at least one commercial advertisement, the encoded identification signal being produced by modulating a first code signal having a predetermined nonzero bandwidth and not derived from the audio signal portion with an identification signal having a narrower bandwidth than the predetermined nonzero bandwidth, correlating the audio signal portion with a second code signal corresponding to the first code signal and not derived from the audio signal portion to produce a correlated signal, recovering the identification signal from the correlated signal, and assembling data representing the source or sources of the at least one commercial advertisement.

30. A method according to claim 29, further comprising the step of recovering additional information indicating at least one of station, channel and identity of the at least one commercial advertisement from the received encoded broadcast or recorded segment signal.

31. A method according to claim 30, wherein the identification signal identifies at least one of the station and the channel of the at least one commercial advertisement, and the additional information indicates at least the identity of the at least one commercial advertisement.

32. A method of encoding information in audio signals to be broadcast or recorded, comprising the steps of:

modulating a first code signal having a predetermined nonzero bandwidth and a plurality of frequency components simultaneously present therein with an identification signal having a narrower bandwidth than the predetermined nonzero bandwidth to produce an encoded identification signal having a broader bandwidth than the identification signal, and mixing the encoded identification signal with an audio signal to be broadcast or recorded to produce an output signal.

33. A method according to claim 32, further comprising the step of mixing the output signal with an additional information signal.

34. A method according to claim 32, further comprising the step of low pass filtering the encoded identification signal before mixing with the audio signal.

35. A method according to claim 32, further comprising the step of inverse transforming the encoded identification signal before mixing with the audio signal.

36. A method according to claim 32, further comprising the step of frequency synthesizing according to predetermined code data to produce the first code signal.

37. A method according to claim 32, wherein the step of modulating comprises modulating a code signal having a frequency spectrum matched to a frequency response characteristic of a device for acoustically reproducing the audio signal as broadcast or recorded.

38. A method according to claim 32, wherein the step of modulating comprises modulating a code signal having a frequency range of approximately 300-3000 Hz.

39. A method according to claim 32, in combination with the steps of receiving the output signal, correlating the received output signal with a second code signal corresponding to the first code signal to recover the identification signal, and storing the recovered identification signal as stored data.

40. A method according to claim 39, wherein the steps of receiving, correlating and storing are performed at each of a plurality of sites, and further comprising the step of sending stored data from the plurality of sites to a centralized facility.

93. A method according to claim 32, wherein the step of modulating comprises modulating a television identification code signal with an identification signal for a television broadcast to produce an encoded television identification signal, and modulating a radio identification code signal different from the television identification code signal with an identification signal for a radio broadcast to produce an encoded radio identification signal, and the step of mixing comprises mixing the encoded television identification signal with a first audio signal to be broadcast as part of a television signal, and mixing the encoded radio identification signal with a second audio signal to be broadcast as part of a radio broadcast.

95. A method according to claim 32, wherein the step of modulating comprises modulating the first code signal at a plurality of broadcasting locations with respective identification signals and the step of mixing comprises mixing a respective encoded identification signal with a corresponding one of a plurality of broadcast signals including at least one radio broadcast signal and at least one television broadcast signal.

97. A method according to claim 32, wherein the step of modulating comprises modulating a geographic area code signal corresponding with a predetermined geographic area with the identification signal.

41. A method of encoding information in audio signals to be broadcast or recorded and detecting the encoded information therein, comprising the steps of:

modulating a first code signal having a predetermined nonzero bandwidth with an identification signal having a narrower bandwidth than the predetermined nonzero bandwidth to produce an encoded signal, mixing the encoded identification signal with an audio signal to produce an output signal, the first code signal not being derived from the audio signal, transducing the output signal in acoustically reproduced form in which the encoded identification signal is imperceptible as information by a listener to produce a transduced signal, correlating the transduced signal with a second code signal corresponding to the first code signal and not derived from the audio signal to produce a correlated signal, recovering the identification signal from the correlated signal, and storing the recovered identification signal as stored data.

42. A method according to claim 41, wherein the step of modulating the first code signal comprises modulating the code signal with an identification signal including information identifying a source of an encoded broadcast, and further comprising the steps of determining an identity of an audience member within audible range of the acoustically reproduced output signal at each of a plurality of sites and transmitting the information identifying the source of the encoded broadcast and the identity of the audience member at each of the plurality of sites to a centralized data processing facility for producing an estimate of the audience for the encoded broadcast.

43. An apparatus for detecting encoded information in broadcast or recorded audio signals, comprising:

means for receiving an encoded broadcast or recorded segment signal including an audio signal portion having an encoded identification signal, the encoded identification signal being produced by modulating a first code signal having a predetermined nonzero bandwidth and not derived from the audio signal portion with an identification signal having a narrower bandwidth than the predetermined nonzero bandwidth, means for correlating the audio signal portion with a second code signal corresponding to the first code signal and not derived from the audio signal portion to produce a correlated signal, and means for recovering the identification signal from the correlated signal.

44. An apparatus according to claim 43, further comprising means for synchronizing the second code signal with the encoded identification signal, and wherein the means for correlating is operative to correlate the audio signal portion with the synchronized second code signal.

45. An apparatus according to claim 43, further including means for transforming the audio signal portion to frequency domain information.

46. An apparatus according to claim 43, wherein the means for correlating comprises means for multiplying the audio signal portion with the second code signal to produce a multiplied signal and wherein the means for recovering comprises means for integrating the multiplied signal.

47. An apparatus according to claim 43, further comprising means for frequency synthesizing in accordance with code data to produce the second code signal.

48. An apparatus according to claim 47, wherein the means for correlating comprises means for mixing the audio signal portion with the second code signal.

49. An apparatus according to claim 43, further comprising means for storing the recovered identification signal as stored data.

50. An apparatus according to claim 49, comprising a plurality of devices each including the means for receiving, the means for correlating and the means for storing, each of the devices being located at a respective one of a plurality of sites, and further comprising means for sending the stored data from each of the plurality of sites to a centralized data processing facility.

51. An apparatus according to claim 43, further comprising means for recovering additional information identifying at least one of station, channel and segment identity from the received encoded broadcast or recorded segment signal.

52. An apparatus according to claim 51, further comprising means for storing the recovered identification signal with the additional information.

53. An apparatus according to claim 51, wherein the received encoded broadcast or recorded segment signal includes the additional information in the audio signal portion.

54. An apparatus according to claim 53, wherein the received encoded broadcast or recorded segment signal includes the additional information substantially in audio signal frequencies above 3000 Hz.

55. An apparatus according to claim 43, further comprising receiving means for receiving a further broadcast including encoded broadcast data produced by modulating a third code signal having a selected bandwidth with a broadcast data signal having a narrower bandwidth than the selected bandwidth;

and means for correlating the further broadcast with a fourth code signal corresponding with the third code signal to recover the broadcast data signal.

56. An apparatus according to claim 43, wherein the means for receiving the audio signal portion is operative to receive the audio signal portion from a device carried on the person of an audience member.

86. An apparatus according to claim 55, wherein the further broadcast is an FM broadcast.

88. An apparatus according to claim 56, further comprising means for supplying the audio signal portion to a means for converting the audio signal portion into an acoustic signal for use by the audience member.

90. An apparatus according to claim 43, further comprising means for sensing recording of the encoded broadcast segment signal by a recording means.

57. An apparatus for detecting encoded information in broadcast or recorded audio signals, comprising:

means for transducing an acoustically reproduced audio signal portion of an encoded broadcast or recorded segment signal to produce a transduced audio signal portion, the audio signal portion having an encoded identification signal produced by modulating a first code signal having a predetermined nonzero bandwidth and not derived from the audio signal portion with an identification signal having a narrower bandwidth than the predetermined nonzero bandwidth, the encoded identification signal being imperceptible as information in the acoustically reproduced audio signal portion, means for correlating the transduced audio signal portion with a second code signal corresponding to the first code signal and not derived from the audio signal portion to produce a correlated signal, and means for recovering the identification signal from the correlated signal.

58. An apparatus according to claim 57, further comprising means for determining an identity of an audience member within audible range of the acoustically reproduced audio signal portion.

59. An apparatus according to claim 58, wherein the means for transducing is operative to transduce an acoustically reproduced audio signal portion of an encoded broadcast wherein the audio signal portion is encoded with an identification signal including information identifying a source of the encoded broadcast, and further comprising means for transmitting the information identifying the source and information indicating the identity of the audience member to a centralized data processing facility for producing an estimate of the audience for the encoded broadcast.

60. An apparatus according to claim 58, wherein the identification signal identifies a source of the encoded broadcast or recorded segment signal.

61. An apparatus according to claim 60, further comprising means for assembling the identity of the audience member and the source of the encoded broadcast or recorded segment signal with a designation of the identity of the encoded broadcast or recorded segment signal.

62. An apparatus according to claim 58, wherein the identification signal identifies one of a source of the encoded broadcast or recorded segment signal and a designation of the identity of the encoded broadcast or recorded segment signal, and further comprising means for assembling data associating the identity of the audience member with the one of a source of the encoded broadcast or recorded segment signal and the designation of the identity of the encoded broadcast or recorded segment signal.

63. An apparatus according to claim 58, wherein the means for transducing and the means for correlating are located within a device carried on the person of the audience member.

64. An apparatus according to claim 58, wherein the means for transducing is located within a first device carried on the person of the audience member, and the means for correlating is located within a second device, and further comprising means for wirelessly transmitting the audio signal portion from the first device to the second device.

65. An apparatus according to claim 58, further comprising means for storing the recovered identification signal with a timestamp as stored data.

66. An apparatus according to claim 58, wherein the means for correlating the audio signal portion is operative to produce the correlated signal only during a predetermined audience survey time period.

67. An apparatus according to claim 66, further comprising means for limiting operation of the correlating means to the predetermined audience survey time period based on the second code signal.

68. An apparatus for determining a source or sources of at least one copyrighted work included in broadcast or recorded audio signals, comprising:

means for receiving an encoded broadcast or recorded segment signal including at least one copyrighted work, the at least one copyrighted work including an audio signal portion having an encoded identification signal indicating a source of said at least one copyrighted work, the encoded identification signal being produced by modulating a first code signal having a predetermined nonzero bandwidth and not derived from the audio signal portion with an identification signal having a narrower bandwidth than the predetermined nonzero bandwidth, means for correlating the audio signal portion with a second code signal corresponding to the first code signal and not derived from the audio signal portion to produce a correlated signal, means for recovering the identification signal from the correlated signal, and means for assembling data representing the source or sources of the at least one copyrighted work.

69. An apparatus according to claim 68, further comprising means for recovering additional information identifying at least one of station, channel and identity of the at least one copyrighted work from the received encoded broadcast or recorded segment signal.

70. An apparatus according to claim 69, wherein the identification signal identifies at least one of the station and the channel of the at least one copyrighted work, and the additional information identifies at least the identity of the at least one copyrighted work.

92. An apparatus according to claim 68, including a plurality of devices each including the means for receiving and the means for correlating, each of the devices being located at a respective one of a plurality of sites, and further comprising means for analyzing the recovered identification signals from the plurality of sites and the assembled data representing the source or sources of the at least one copyrighted work to detect unauthorized copying.

71. An apparatus for determining a source or sources of at least one commercial advertisement in broadcast or recorded audio signals, comprising:

means for receiving an encoded broadcast or recorded segment signal including at least one commercial advertisement, the at least one commercial advertisement including an audio signal portion having an encoded identification signal indicating a source of the at least one commercial advertisement, the encoded identification signal being produced by modulating a first code signal having a predetermined nonzero bandwidth and not derived from the audio signal portion with an identification signal having a narrower bandwidth than the predetermined nonzero bandwidth, means for correlating the audio signal portion with a second code signal corresponding with the first code signal and not derived from the audio signal portion to produce a correlated signal, means for recovering the identification signal from the correlated signal, and means for assembling data representing the source or sources of the at least one commercial advertisement.

72. An apparatus according to claim 71, further comprising means for recovering additional information identifying at least one of station, channel and identity of the at least one commercial advertisement from the received encoded broadcast or recorded segment signal.

73. An apparatus according to claim 72 wherein the identification signal identifies at least one of the station and the channel of the at least one commercial advertisement, and the additional information identifies at least the identity of the at least one commercial advertisement.

74. An apparatus for encoding information in audio signals to be broadcast or recorded, comprising:

means for modulating a first code signal having a predetermined nonzero bandwidth and a plurality of frequency components simultaneously present therein with an identification signal having a narrower bandwidth than the predetermined nonzero bandwidth to produce an encoded identification signal having a broader bandwidth than the identification signal, and means for mixing the encoded identification signal with an audio signal to be broadcast or recorded to produce an output signal.

75. An apparatus according to claim 74, further comprising means for mixing the output signal with an additional information signal.

76. An apparatus according to claim 74, further comprising means for low pass filtering the encoded identification signal and wherein the means for mixing is operative to mix the filtered encoded identification signal with the broadcast or recorded audio signal.

77. An apparatus according to claim 74, further comprising means for inverse transforming the encoded identification signal and wherein the means for mixing is operative to mix the inverse transformed encoded identification signal with the audio signal.

78. An apparatus according to claim 74, further comprising means for frequency synthesizing according to predetermined code data to produce the first code signal.

79. An apparatus according to claim 74, wherein the modulating means is operative to modulate a code signal having a frequency spectrum matched to a frequency response characteristic of a device for acoustically reproducing the audio signal as broadcast or recorded.

80. An apparatus according to claim 74, wherein the modulating means is operative to modulate a code signal having a frequency range of approximately 300-3000 Hz.

81. An apparatus according to claim 74, in combination with means for receiving the output signal, means for correlating the received output signal with a second code signal to recover the identification signal, and means for storing the recovered identification signal as stored data.

82. An apparatus according to claim 81, further comprising a plurality of devices each including the means for receiving, the means for correlating and the means for storing, each of the devices being located at a respective one of a plurality of sites, and means for sending stored data from each of the plurality of sites to a centralized data processing facility.

94. An apparatus according to claim 74, wherein the means for modulating comprises first modulating means for modulating a television identification code signal with an identification signal for a television broadcast to produce an encoded television identification signal, and second modulating means for modulating a radio identification code signal different from the television identification code signal with an identification signal for a radio broadcast to produce an encoded radio identification signal, and wherein the mixing means comprises first mixing means for mixing the encoded television identification signal with a first audio signal to be broadcast as part of a television signal, and second mixing means for mixing the encoded radio identification signal with a second audio signal to be broadcast as part of a radio broadcast.

96. An apparatus according to claim 74, wherein the means for modulating comprises a plurality of modulating means for each modulating the first code signal with a respective identification signal and a plurality of mixing means for each mixing a respective one of the encoded identification signals with a corresponding one of a plurality of broadcast signals including at least one radio broadcast signal and at least one television broadcast signal.

98. An apparatus according to claim 74, wherein the means for modulating is operative to modulate a geographic area code signal corresponding with a predetermined geographic area with the identification signal.

83. An apparatus for encoding information in audio signals to be broadcast or recorded and detecting the encoded information therein, comprising:

means for modulating a first code signal having a predetermined nonzero bandwidth with an identification signal having a narrower bandwidth than the predetermined nonzero bandwidth to produce an encoded signal, means for mixing the encoded identification signal with an audio signal to produce an output signal, the first code signal not being derived from the audio signal, means for transducing the output signal in acoustically reproduced form in which the encoded identification signal is imperceptible as information by a listener to produce a transduced signal, means for correlating the transduced signal with a second code signal corresponding to the first code signal and not derived from the audio signal to produce a correlated signal, means for recovering the identification signal from the correlated signal, and means for storing the recovered identification signal as stored data.

84. An apparatus according to claim 83, wherein the means for modulating the first code signal comprises means for modulating the first code signal with an identification signal including information identifying a source of an encoded broadcast, and further comprising means for determining an identity of an audience member within audible range of the acoustically reproduced output signal at each of a plurality of sites and means for transmitting the information identifying the source of the encoded broadcast and the identity of the audience member at each of the plurality of sites to a centralized data processing facility for producing an estimate of the audience for the encoded broadcast.

99. An encoded broadcast signal produced by:

providing a broadcast signal including an audio signal, modulating a code signal having a predetermined nonzero bandwidth and a plurality of frequency components simultaneously present therein with an identification signal having a narrower bandwidth than the predetermined nonzero bandwidth to produce an encoded identification signal having a broader bandwidth than the identification signal, and mixing the encoded identification signal with the audio signal to produce the encoded broadcast signal.

100. An encoded recorded signal produced by:

providing a signal to be recorded including an audio signal, modulating a code signal having a predetermined nonzero bandwidth and a plurality of frequency components simultaneously present therein with an identification signal having a narrower bandwidth than the predetermined nonzero bandwidth to produce an encoded identification signal having a broader bandwidth than the identification signal, mixing the encoded identification signal with the audio signal to produce an encoded recording signal, and recording the encoded recording signal to produce the encoded recorded signal.

101. A method of encoding information in audio signals to be broadcast or recorded, comprising the steps of:

receiving an identification signal including received identification symbols;

providing a memory means containing digital data representing groups of frequencies each corresponding to a respective one of the received identification symbols;

for each of the received identification symbols, reading digital data representing the corresponding group of frequencies from the memory means to produce an encoded signal; and

mixing the encoded signal with the audio signal to be broadcast or recorded to produce an output signal.

102. A method according to claim 101, wherein each of the groups of frequencies in the memory means is represented as time domain digital data.

103. A method according to claim 101, further comprising the step of digital to analog converting the encoded signal before the step of mixing.

104. A method according to claim 101, further comprising the step of storing the groups of frequencies in the memory means at respective address ranges.

105. A method according to claim 104, wherein the memory means is located at an encoding site, and further comprising the step of downloading the digital data representing the groups of frequencies to the memory means from a master site separate from the encoding site.

106. An apparatus for encoding information in audio signals to be broadcast or recorded, comprising:

means for receiving an identification signal including received identification symbols;

memory means for storing digital data representing plural groups of frequencies, each of the plural groups of frequencies corresponding to a respective one of the received identification symbols;

means for reading from the memory means digital data representing a respective one of the plural groups of frequencies in response to each of the identification symbols to produce an encoded signal; and

means for mixing the encoded signal with the audio signal to be broadcast or recorded to produce an output signal.

107. An apparatus according to claim 106, wherein each of the plural groups of frequencies in the memory means is represented as time domain digital data.

108. An apparatus according to claim 106, further comprising means for digital to analog converting the encoded signal to produce an analog encoded signal for mixing with the audio signal.

109. An apparatus according to claim 106, further comprising means for storing the plural groups of frequencies in the memory means at respective address ranges.

110. An apparatus according to claim 109, wherein the memory means is located at an encoding site, and further comprising means for downloading the digital data representing the plural groups of frequencies to the memory means from a master site separate from the encoding site.