Apparatus and method for encoding and decoding information in analog signals
First Claim
1. A method for encoding information symbols onto an analog host signal, comprising the steps of:
- determining a short-term autocorrelation function value of said host signal;
determining a value of an auxiliary information signal containing an information symbol;
calculating a value of the short-term autocorrelation function of said host signal corresponding to said determined value of said auxiliary information signal according to a predefined relationship between auxiliary information signal value and host signal autocorrelation value;
developing a host modifying signal for modifying said host signal such that the short-term autocorrelation function value of the modified host signal will correspond to said calculated value; and
modifying said host signal with said host modifying signal.
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Abstract
Apparatus and methods are provided for encoding, storing and decoding auxiliary information on an analog source signal in a way which has minimal impact on the human perception of the source information when the source signal is applied to an appropriate output device, such as a speaker or a display monitor. The autocorrelation function of a host signal is modulated according to the value of an auxiliary information signal by adding a host modifying signal to the host signal. The auxiliary signal is decoded by generating the autocorrelation function of the encoded signal and extracting the auxiliary signal according to well-known signal extraction techniques.
278 Citations
27 Claims
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1. A method for encoding information symbols onto an analog host signal, comprising the steps of:
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determining a short-term autocorrelation function value of said host signal; determining a value of an auxiliary information signal containing an information symbol; calculating a value of the short-term autocorrelation function of said host signal corresponding to said determined value of said auxiliary information signal according to a predefined relationship between auxiliary information signal value and host signal autocorrelation value; developing a host modifying signal for modifying said host signal such that the short-term autocorrelation function value of the modified host signal will correspond to said calculated value; and modifying said host signal with said host modifying signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method for decoding information symbols encoded onto an analog host signal, comprising the steps of:
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calculating a short-term autocorrelation function of said encoded host signal; determining the value of said calculated autocorrelation function; and determining a value of an information symbol as a function of the value of said calculated autocorrelation function and a predefined relationship between information symbol values and autocorrelation function values. - View Dependent Claims (18, 19, 20)
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21. Apparatus for encoding information symbols onto an analog host signal, comprising:
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means for determining a short-term autocorrelation function value of said host signal; means for determining a value of an auxiliary information signal containing an information symbol; means for calculating a value of the short-term autocorrelation function of said host signal corresponding to said determined value of said auxiliary information signal according to a predefined relationship between auxiliary information signal value and host signal autocorrelation value; means for developing a host modifying signal for modifying said host signal such that the short-term autocorrelation function value of the modified host signal will correspond to said calculated value; and means for modifying said host signal with said host modifying signal.
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22. Apparatus for decoding information symbols encoded onto an analog host signal, comprising:
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means for calculating a short-term autocorrelation function of said encoded host signal; means for determining the value of said calculated autocorrelation function; and means for determining a value of an information symbol as a function of the value of said calculated autocorrelation function and a predefined relationship between information symbol values and autocorrelation function values.
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23. A method for encoding information symbols onto an analog host signal, comprising the steps of:
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determining a short-term autocorrelation function value of said analog host signal; determining a value of an auxiliary information signal containing an information symbol; developing a host modifying signal for modifying said host signal such that the short-term autocorrelation function value of the modified host signal will correspond to said determined value; and modifying said host signal with said host modifying signal. - View Dependent Claims (24, 25, 26)
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27. A method for decoding information symbols encoded onto an analog host signal, comprising the steps of:
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calculating a short-term autocorrelation function of said encoded host signal; and determining a value of an information symbol as a function of the value of said calculated autocorrelation function and a predefined relationship between information symbol values and autocorrelation function values.
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Specification