Method and apparatus for transporting auxiliary data in audio signals

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.

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.

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.

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.

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.

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.