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US5822360A
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Method and apparatus for transporting auxiliary data in audio signals
Assignee: Verance Corp
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Filing: 1995-09-06
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Granted: 1998-10-13
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Expires: 2015-09-06
Abstract
Abstract Auxiliary data is transported in a conventional audio signal by hiding the data in the form of colored noise. The colored noise has a spectrum that simulates the spectrum of the primary audio signal. The data to be transported is first converted to a spread spectrum signal. The primary audio signal is analyzed to determine its spectral shape. The same spectral shape is imparted to the spread spectrum signal, which is then combined with the primary audio signal for transmission. The spectral shaping can be performed using time domain modeling and synthesis such as linear predictive coding or by using subband coding techniques such as fast Fourier transforms. A plurality of different auxiliary information streams can be transported on the audio signal. By adjusting the gain of individual spread spectrum signal carrier(s) and the power of the colored noise, the auxiliary information stream(s) can be rendered inaudible in the primary audio signal, or at any desired level below or above an audible threshold.
Inventors
- 👤 Chong U. Lee
- 👤 Kamran Moallemi
- 👤 Robert L. Warren
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 06:37
CPC Classifications
H; H04; H04B; H04B15/00; H04H; H04H20/00; H04H20/28; H04H20/30; H04H20/31; G; G10; G10L; G10L19/00; G10L19/018; H04B1/00; H04B1/66; H04B1/665; H04B1/69; H04B1/707; H04J; H04J13/00; H04J7/00; H04J9/00; H04J99/00; H04B15/02; H04B15/04; H04J13/0077
Claims Analysis
Total Claims: 71
Claim 1
Independent Claim
116 words
A method for transporting auxiliary information in an audio signal, comprising the steps of: modulating a pseudorandom noise carrier by said auxiliary information to provide a spread spectrum signal carrying said information on a carrier portion thereof; evaluating said audio signal using time domain modeling to obtain an approximation of its spectral shape; and using time domain synthesis responsive to said time domain modeling to provide a synthesis filter; and inputting said spread spectrum signal to said synthesis filter to spectrally shape the carrier portion of said spread spectrum signal to simulate the spectral shape of said audio signal, thereby producing a colored noise signal containing said auxiliary information to be carried in said audio signal.
Claim 2
Independent Claim
116 words
A method for transporting auxiliary information in an audio signal, comprising the steps of: modulating a pseudorandom noise carrier by said auxiliary information to provide a spread spectrum signal carrying said information on a carrier portion thereof; evaluating said audio signal using time domain modeling to obtain an approximation of its spectral shape; and using time domain synthesis responsive to said time domain modeling to provide a synthesis filter; and inputting said spread spectrum signal to said synthesis filter to spectrally shape the carrier portion of said spread spectrum signal to simulate the spectral shape of said audio signal, thereby producing a colored noise signal containing said auxiliary information to be carried in said audio signal.
Claim 3
Dependent Claim
58 words
A method in accordance with claim 1 comprising the further step of: adjusting the power of said colored noise signal to provide it at a desired level in said audio signal; and combining said power adjusted colored noise signal with said audio signal to produce an output signal carrying said auxiliary information as noise in said audio signal.
Claim 4
Dependent Claim
31 words
A method in accordance with claim 1 wherein said pseudorandom noise carrier is generated cryptographically according to a cryptographic key to provide secure communication of said auxiliary information to said receiver.
Claim 5
Dependent Claim
101 words
A method for recovering said auxiliary information from a received audio signal carrying the colored noise signal of claim 1, comprising the steps of: evaluating said received audio signal using time domain modeling to approximate its spectral shape; using time domain prediction responsive to said time domain modeling to provide a prediction filter; said prediction filter having a transfer function which is approximately an inverse of a transfer function of said synthesis filter; inputting said received audio signal to said prediction filter to whiten the colored noise signal contained therein; and demodulating the whitened noise signal to recover said auxiliary information.
Claim 6
Dependent Claim
24 words
A method in accordance with claim 4 wherein: said received audio signal comprises the sum of said colored noise signal and said audio signal.
Claim 7
Dependent Claim
34 words
A method in accordance with claim 4 wherein: said time domain modeling comprises linear predictive coding (LPC) to provide LPC coefficients for use in said prediction filter during said spectrally shaping and whitening steps.
Claim 8
Dependent Claim
37 words
A method in accordance with claim 6 wherein: the LPC coefficients used during said whitening step are derived from said received audio signal independently of the derivation of the LPC coefficients used during said spectrally shaping step.
Claim 9
Dependent Claim
87 words
A method in accordance with claim 1 wherein a plurality of auxiliary information signals are transported on said audio signal, said method comprising the further steps of: modulating a plurality of pseudorandom noise carriers by said auxiliary information signals to provide a plurality of spread spectrum signals; spectrally shaping said carriers to simulate the spectral shape of said audio signal; and combining the spectrally shaped carriers with said audio signal to produce an output signal carrying said auxiliary information signals as colored noise in said audio signal.
Claim 10
Dependent Claim
24 words
A method in accordance with claim 8 wherein each of said carriers is individually spectrally shaped prior to its combination with said audio signal.
Claim 11
Dependent Claim
35 words
A method in accordance with claim 8 wherein said carriers are combined before said spectrally shaping step, and said combined carriers are spectrally shaped as a group prior to their combination with said audio signal.
Claim 12
Dependent Claim
55 words
A method in accordance with claim 8 wherein: at least one of said carriers is individually spectrally shaped prior to its combination with said audio signal, and at least two other of said carriers are combined before said spectrally shaping step and spectrally shaped as a group prior to their combination with said audio signal.
Claim 13
Dependent Claim
52 words
A method in accordance with claim 8 wherein: the spectrally shaped carriers are combined with said audio signal such that at least one of said spectrally shaped carriers is combined with said audio signal after said audio signal has already been combined with at least one other of said spectrally shaped carriers.
Claim 14
Dependent Claim
35 words
A method in accordance with claim 8 comprising the further step of providing at least one of a modulated or unmodulated pseudorandom noise carrier as a pilot signal for use in synchronizing a receiver function.
Claim 15
Dependent Claim
32 words
A method in accordance with claim 8 comprising the further step of: adjusting the gain of at least one of said spectrally shaped carriers prior to its combination with said audio signal.
Claim 16
Dependent Claim
35 words
A method in accordance with claim 14 comprising the further step of: adjusting the power of the spectrally shaped carriers as a group to provide the group at a desired level in said audio signal.
Claim 17
Dependent Claim
56 words
A method in accordance with claim 8 comprising the further steps of: determining the gain of at least a first one of the spectrally shaped carriers; and adjusting the gain of at least a second one of the spectrally shaped carriers in response to the gain determined for the at least one first spectrally shaped carrier.
Claim 18
Dependent Claim
40 words
A method in accordance with claim 16 comprising the further step of: adjusting the power of at least said first and second spectrally shaped carriers as a group to provide the group at a desired level in said audio signal.
Claim 19
Dependent Claim
22 words
A method in accordance with claim 8 wherein at least two of said spectrally shaped carriers are provided at different data rates.
Claim 20
Dependent Claim
65 words
A method for recovering said auxiliary information from the output signal of claim 8 comprising the steps of: evaluating said output signal to approximate its spectral shape; processing the output signal, based on the approximate spectral shape determined therefor, to whiten said colored noise; and demodulating a desired spread spectrum signal after said colored noise has been whitened to recover the auxiliary information carried thereby.
Claim 21
Dependent Claim
22 words
A method in accordance with claim 19 wherein a plurality of said spread spectrum signals are demodulated simultaneously from said output signal.
Claim 22
Independent Claim
126 words
A method for transporting a plurality of auxiliary information signals in an audio signal, comprising the steps of: modulating each of a plurality of pseudorandom noise carriers by at least one different one of said auxiliary information signals to provide a plurality of spread spectrum signals carrying auxiliary information on carrier portions thereof; evaluating said audio signal using subband analysis to estimate its spectral shape; subband filtering said plurality of spread spectrum signals in response to said subband analysis for spectrally shaping the carrier portions of said spread spectrum signals to simulate the spectral shape of said audio signal; and combining the spectrally shaped carriers with said audio signal to produce an output signal carrying said auxiliary information signals as colored noise in said audio signal.
Claim 23
Independent Claim
126 words
A method for transporting a plurality of auxiliary information signals in an audio signal, comprising the steps of: modulating each of a plurality of pseudorandom noise carriers by at least one different one of said auxiliary information signals to provide a plurality of spread spectrum signals carrying auxiliary information on carrier portions thereof; evaluating said audio signal using subband analysis to estimate its spectral shape; subband filtering said plurality of spread spectrum signals in response to said subband analysis for spectrally shaping the carrier portions of said spread spectrum signals to simulate the spectral shape of said audio signal; and combining the spectrally shaped carriers with said audio signal to produce an output signal carrying said auxiliary information signals as colored noise in said audio signal.
Claim 24
Dependent Claim
23 words
A method in accordance with claim 21 wherein said evaluating and subband filtering steps comprise fast Fourier transform (FFT) analysis and filtering, respectively.
Claim 25
Dependent Claim
24 words
A method in accordance with claim 21 wherein each of said carriers is individually spectrally shaped prior to its combination with said audio signal.
Claim 26
Dependent Claim
35 words
A method in accordance with claim 21 wherein said carriers are combined before said spectrally shaping step, and said combined carriers are spectrally shaped as a group prior to their combination with said audio signal.
Claim 27
Dependent Claim
55 words
A method in accordance with claim 21 wherein: at least one of said carriers is individually spectrally shaped prior to its combination with said audio signal, and at least two other of said carriers are combined before said spectrally shaping step and spectrally shaped as a group prior to their combination with said audio signal.
Claim 28
Dependent Claim
40 words
A method in accordance with claim 21 wherein: at least one of said spectrally shaped carriers is combined with said audio signal after said audio signal has already been combined with at least one other of said spectrally shaped carriers.
Claim 29
Dependent Claim
35 words
A method in accordance with claim 21 comprising the further step of providing at least one of a modulated or unmodulated pseudorandom noise carrier as a pilot signal for use in synchronizing a receiver function.
Claim 30
Dependent Claim
32 words
A method in accordance with claim 21 comprising the further step of: adjusting the gain of at least one of said spectrally shaped carriers prior to its combination with said audio signal.
Claim 31
Dependent Claim
35 words
A method in accordance with claim 28 comprising the further step of: adjusting the power of the spectrally shaped carriers as a group to provide the group at a desired level in said audio signal.
Claim 32
Dependent Claim
56 words
A method in accordance with claim 21 comprising the further steps of: determining the gain of at least a first one of the spectrally shaped carriers; and adjusting the gain of at least a second one of the spectrally shaped carriers in response to the gain determined for the at least one first spectrally shaped carrier.
Claim 33
Dependent Claim
40 words
A method in accordance with claim 30 comprising the further step of: adjusting the power of at least said first and second spectrally shaped carriers as a group to provide the group at a desired level in said audio signal.
Claim 34
Dependent Claim
22 words
A method in accordance with claim 21 wherein at least two of said spectrally shaped carriers are provided at different data rates.
Claim 35
Dependent Claim
65 words
A method for recovering said auxiliary information from the output signal of claim 21 comprising the steps of: evaluating said output signal to approximate its spectral shape; processing the output signal, based on the approximate spectral shape determined therefor, to whiten said colored noise; and demodulating a desired spread spectrum signal after said colored noise has been whitened to recover the auxiliary information carried thereby.
Claim 36
Dependent Claim
22 words
A method in accordance with claim 33 wherein a plurality of said spread spectrum signals are demodulated simultaneously from said output signal.
Claim 37
Dependent Claim
114 words
Apparatus for transporting auxiliary information in an audio signal for communication to a receiver, comprising means for converting a data stream of said auxiliary information into a spread spectrum signal carrying said information; means for evaluating said audio signal using tine domain modeling to obtain an approximation of its spectral shape; a time domain synthesizer responsive to said evaluating means for providing a synthesis filter; and means for inputting said spread spectrum signal to said synthesis filter for spectrally shaping a carrier portion of said spread spectrum signal to simulate the spectral shape of said audio signal, thereby producing a colored noise signal containing said auxiliary information to be carried in said audio signal.
Claim 38
Dependent Claim
114 words
Apparatus for transporting auxiliary information in an audio signal for communication to a receiver, comprising means for converting a data stream of said auxiliary information into a spread spectrum signal carrying said information; means for evaluating said audio signal using tine domain modeling to obtain an approximation of its spectral shape; a time domain synthesizer responsive to said evaluating means for providing a synthesis filter; and means for inputting said spread spectrum signal to said synthesis filter for spectrally shaping a carrier portion of said spread spectrum signal to simulate the spectral shape of said audio signal, thereby producing a colored noise signal containing said auxiliary information to be carried in said audio signal.
Claim 39
Dependent Claim
34 words
Apparatus in accordance with claim 35 further comprising: means for combining said colored noise signal with said audio signal to produce an output signal carrying said auxiliary information as noise in said audio signal.
Claim 40
Dependent Claim
34 words
Apparatus in accordance with claim 36 further comprising: means for adjusting the power of said colored noise signal prior to said combining means to provide it at a desired level in said audio signal.
Claim 41
Dependent Claim
42 words
Apparatus in accordance with claim 35 wherein: said evaluating means comprise a linear predictive coding (LPC) processor coupled to receive said audio signal and generate LPC coefficients therefrom; and said time domain synthesizer comprises an LPC filter responsive to said LPC coefficients.
Claim 42
Dependent Claim
109 words
Apparatus for recovering said auxiliary information from a received audio signal carrying the colored noise signal provided by the apparatus of claim 35, comprising: means for evaluating said received audio signal using time domain modeling to approximate its spectral shape; means for using time domain prediction responsive to said time domain modeling to provide a prediction filter; said prediction filter having a transfer function which is approximately an inverse of a transfer function of said synthesis filter; means for inputting said received audio signal to said prediction filter to whiten the colored noise signal contained therein; and means for demodulating the whitened noise signal to recover said data stream.
Claim 43
Dependent Claim
90 words
Apparatus in accordance with claim 39 wherein: said means for evaluating said audio signal comprise a first linear predictive coding (LPC) processor coupled to receive said audio signal and generate first LPC coefficients therefrom; said time domain synthesizer comprises a first LPC filter responsive to said first LPC coefficients; said means for evaluating said received audio signal comprise a second LPC processor for generating second LPC coefficients from the received audio signal; and said time domain prediction is implemented using a second LPC filter responsive to said second LPC coefficients.
Claim 44
Dependent Claim
29 words
Apparatus in accordance with claim 40 further comprising: means for adjusting the power of said colored noise signal to render it at a desired level in said audio signal.
Claim 45
Dependent Claim
98 words
Apparatus for transporting a plurality of auxiliary information streams in an audio signal, comprising: means for converting said plurality of auxiliary information streams into spread spectrum signals; means for evaluating said audio signal to obtain an approximation of its spectral shape; and means responsive to said evaluating means for spectrally shaping carrier portions of said spread spectrum signals to simulate the spectral shape of said audio signal; wherein a combination of said spread spectrum signals is used to provide colored noise simulating the spectral shape of said audio signal for carrying said auxiliary information in said audio signal.
Claim 46
Dependent Claim
98 words
Apparatus for transporting a plurality of auxiliary information streams in an audio signal, comprising: means for converting said plurality of auxiliary information streams into spread spectrum signals; means for evaluating said audio signal to obtain an approximation of its spectral shape; and means responsive to said evaluating means for spectrally shaping carrier portions of said spread spectrum signals to simulate the spectral shape of said audio signal; wherein a combination of said spread spectrum signals is used to provide colored noise simulating the spectral shape of said audio signal for carrying said auxiliary information in said audio signal.
Claim 47
Dependent Claim
30 words
Apparatus in accordance with claim 42 further comprising: means for adjusting the gain of at least one of said spectrally shaped carriers prior to its combination with said audio signal.
Claim 48
Dependent Claim
34 words
A method in accordance with claim 43 further comprising: means for adjusting the power of the spectrally shaped carriers as a group to provide the group at a desired level in said audio signal.
Claim 49
Dependent Claim
64 words
Apparatus in accordance with claim 42 further comprising: means for determining the gain of at least one first spectrally shaped carrier to be carried in said audio signal; and means for adjusting the gain of at least one second spectrally shaped carrier to be carried in said audio signal in response to the gain determined for said at least one first spectrally shaped carrier.
Claim 50
Dependent Claim
38 words
Apparatus in accordance with claim 45 further comprising: means for adjusting the power of at least said first and second spectrally shaped carriers as a group to provide the group at a desired level in said audio signal.
Claim 51
Dependent Claim
41 words
Apparatus in accordance with claim 42 wherein: said means for evaluating said audio signal use time domain modeling to obtain said approximation of the audio signal spectral shape; and said means responsive to said evaluating means comprise a time domain synthesizer.
Claim 52
Dependent Claim
41 words
Apparatus in accordance with claim 42 wherein: said means for evaluating said audio signal use subband analysis to obtain said approximation of the audio signal spectral shape; and said means responsive to said evaluating means comprise at least one subband filter.
Claim 53
Dependent Claim
23 words
Apparatus in accordance with claim 48 wherein said subband analyzer and subband filter comprise a fast Fourier transform (FFT) analyzer and filter, respectively.
Claim 54
Dependent Claim
28 words
Apparatus in accordance with claim 42 further comprising: means for adjusting the power of said colored noise to render it at a desired level in said audio signal.
Claim 55
Dependent Claim
43 words
Apparatus in accordance with claim 42 wherein: said plurality of auxiliary information streams have different data rates; and said means for converting said auxiliary information streams into spread spectrum signals comprise pseudorandom sequence generators providing different output rates for the different information streams.
Claim 56
Dependent Claim
32 words
Apparatus in accordance with claim 42 wherein: said means for converting said auxiliary information streams into spread spectrum signals comprise pseudorandom sequence generators providing orthogonal pseudorandom sequences for the different information streams.
Claim 57
Dependent Claim
108 words
A decoder for recovering auxiliary information carried by a spread spectrum signal that is transported as noise in an audio signal, said spread spectrum signal including a carrier that is colored to simulate the spectral shape of audio information contained in said audio signal, said decoder comprising: means for evaluating said audio signal using time domain modeling to approximate its spectral shape, and time domain prediction responsive to said time domain modeling to provide a prediction filter; means for inputting said audio signal to said prediction filter to whiten the colored spread spectrum carrier contained therein; and means for demodulating the whitened carrier to recover said auxiliary information.
Claim 58
Dependent Claim
108 words
A decoder for recovering auxiliary information carried by a spread spectrum signal that is transported as noise in an audio signal, said spread spectrum signal including a carrier that is colored to simulate the spectral shape of audio information contained in said audio signal, said decoder comprising: means for evaluating said audio signal using time domain modeling to approximate its spectral shape, and time domain prediction responsive to said time domain modeling to provide a prediction filter; means for inputting said audio signal to said prediction filter to whiten the colored spread spectrum carrier contained therein; and means for demodulating the whitened carrier to recover said auxiliary information.
Claim 59
Dependent Claim
45 words
A decoder in accordance with claim 53 wherein: said evaluating means comprise a linear predictive coding (LPC) processor coupled to receive said audio signal and generate LPC coefficients therefrom; and said time domain prediction is implemented using an LPC filter responsive to said LPC coefficients.
Claim 60
Dependent Claim
67 words
A decoder in accordance with claim 53 wherein: a plurality of auxiliary information signals are carried on respective carriers of said spread spectrum signal, all of said carriers being spectrally shaped to simulate the spectral shape of said audio information; and said demodulator means include means for selecting at least one desired carrier for demodulation to enable the recovery of at least one corresponding auxiliary information signal.
Claim 61
Dependent Claim
64 words
A decoder in accordance with claim 53 wherein: a plurality of auxiliary information signals are carried on respective carriers of said spread spectrum signal, all of said carriers being spectrally shaped to simulate the spectral shape of said audio information; and said demodulator means include means for simultaneously demodulating a plurality of said carriers to enable the simultaneous recovery of said auxiliary information signals.
Claim 62
Dependent Claim
118 words
A decoder for recovering a plurality of auxiliary information streams carried by a spread spectrum signal that is transported as noise in an audio signal, said spread spectrum signal including a plurality of carriers that are colored to simulate the spectral shape of audio information contained in said audio signal, said decoder comprising: means for evaluating said audio signal using time domain modeling to determine its approximate spectral shape; means for using time domain prediction responsive to said time domain modeling to provide a prediction filter; means for inputting said audio signal to said prediction filter to whiten the colored spread spectrum carriers contained therein; and means for demodulating the whitened carriers to recover said auxiliary information streams.
Claim 63
Dependent Claim
118 words
A decoder for recovering a plurality of auxiliary information streams carried by a spread spectrum signal that is transported as noise in an audio signal, said spread spectrum signal including a plurality of carriers that are colored to simulate the spectral shape of audio information contained in said audio signal, said decoder comprising: means for evaluating said audio signal using time domain modeling to determine its approximate spectral shape; means for using time domain prediction responsive to said time domain modeling to provide a prediction filter; means for inputting said audio signal to said prediction filter to whiten the colored spread spectrum carriers contained therein; and means for demodulating the whitened carriers to recover said auxiliary information streams.
Claim 64
Dependent Claim
45 words
A decoder in accordance with claim 57 wherein: said evaluating means comprise a linear predictive coding (LPC) processor coupled to receive said audio signal and generate LPC coefficients therefrom; and said time domain prediction is implemented using an LPC filter responsive to said LPC coefficients.
Claim 65
Dependent Claim
96 words
A decoder for recovering auxiliary information carried by a spread spectrum signal transported as noise in an audio signal, comprising: means for whitening a spectrum of said audio signal, said whitening means creating intersymbol interference in said spread spectrum signal; and a rake receiver for receiving and demodulating said audio signal from said whitening means; said rake receiver having a plurality of fingers for processing different multipaths of said spread spectrum signal when demodulating the received audio signal, thereby recovering said spread spectrum signal with reduced intersymbol interference in order to obtain said auxiliary information therefrom.
Claim 66
Dependent Claim
96 words
A decoder for recovering auxiliary information carried by a spread spectrum signal transported as noise in an audio signal, comprising: means for whitening a spectrum of said audio signal, said whitening means creating intersymbol interference in said spread spectrum signal; and a rake receiver for receiving and demodulating said audio signal from said whitening means; said rake receiver having a plurality of fingers for processing different multipaths of said spread spectrum signal when demodulating the received audio signal, thereby recovering said spread spectrum signal with reduced intersymbol interference in order to obtain said auxiliary information therefrom.
Claim 67
Dependent Claim
73 words
A decoder in accordance with claim 59 wherein said whitening means comprise: a linear predictive coding (LPC) processor coupled to receive said audio signal and generate LPC coefficients therefrom, and an LPC filter of order N for receiving said audio signal and responsive to said LPC coefficients for whitening said spectrum of said audio signal; said rake receiver comprising N fingers, where N is approximately equal to the order of said LPC filter.
Claim 68
Dependent Claim
39 words
A decoder in accordance with claim 59 wherein said whitening means comprise: a subband analyzer coupled to receive and estimate the spectrum of said audio signal; and a subband filter responsive to the spectrum estimated by said subband analyzer.
Claim 69
Dependent Claim
32 words
A decoder in accordance with claim 59 wherein each of said fingers has an associated weight, said rake receiver further comprising: means for individually adjusting the weights of said rake receiver fingers.
Claim 70
Dependent Claim
18 words
A decoder in accordance with claim 62 wherein the weights of said rake receiver fingers are dynamically adjustable.
Claim 71
Dependent Claim
22 words
A decoder in accordance with claim 63 wherein said weights are dynamically adjustable in response to coefficients generated by said whitening means.
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