Cross-term compensation power adjustment of embedded auxiliary data in a primary data signal

• US 5,940,429 A
• Filed: 02/25/1997
• Issued: 08/17/1999
• Est. Priority Date: 02/25/1997
• Status: Expired due to Term

• Current Assignee: Verance Corporation
• Original Assignee: Solana Technology Development Corp. (Verance Corporation)
• Inventors: Lee, Chong U., Lam, S. Katherine
• Primary Examiner(s): LE, AMANDA T
• Application Number:
  US08/805,732
• Time in Patent Office: 903 Days
• Field of Search: 375/200, 375/206, 375/208, 375/209, 375/210, 375/285, 375/296, 370/203, 370/208, 370/209, 370/320, 370/335, 370/342, 370/441, 370/479, 370/522, 370/527, 370/529, 455/105, 455/116
• US Class Current: 375/130
• CPC Class Codes: G10L 19/018 Audio watermarking, i.e. embedding inaudible data in the audio signal
• CPC Class Codes: H04B 1/665 using psychoacoustic properties of the ear, e.g. masking effect
• CPC Class Codes: H04B 1/707 using direct sequence modulation

Abstract

An auxiliary data signal is transported with a primary data signal by hiding the auxiliary data signal in the form of colored noise. The colored noise has a spectrum that simulates the spectrum of the primary data 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 at any desired level below or above an interference threshold in the primary data signal. The power of the colored noise is further compensated to account for a cross-correlation between the primary data signal and the auxiliary data signal to enhance the recovery of the auxiliary data at a decoder.

Claims

1. A method for adjusting the power of an auxiliary data signal which is carried with a primary data signal, comprising the steps of:

providing a cross-term compensation signal which is indicative of a cross-correlation between said auxiliary data signal and said primary data signal; and

adjusting a power of said auxiliary data signal according to said cross-term compensation signal and a desired signal-to-noise ratio to provide said power as a fraction of a power of said primary data signal.

2. The method of claim 1, comprising the further step of:

limiting said cross-term compensation signal to a predetermined range.

3. The method of claim 1, comprising the further steps of:

determining an average amplitude of said primary data signal; and

adjusting the power of said auxiliary data signal according to said average amplitude.

4. The method of claim 1, comprising the further step of:

floor-limiting the power adjustment of said auxiliary data signal.

5. The method of claim 1, comprising the further steps of:

determining an average amplitude of said primary data signal; and

adjusting the power of said auxiliary data signal according to a product of said average amplitude and said desired signal-to-noise ratio.

6. The method of claim 5, comprising the further step of:

limiting a magnitude of said cross-term compensation signal to a magnitude of said product of said average amplitude and said desired signal-to-noise ratio.

7. The method of claim 1, wherein:

said auxiliary data signal is obtained by modulating a pseudorandom noise carrier by auxiliary information to provide a spread spectrum signal carrying said auxiliary information on a carrier portion thereof.

8. The method of claim 1, wherein:

said auxiliary data signal is modulated according to a binary phase-shift keying (BPSK) technique.

9. The method of claim 1, comprising the further step of:

spectrally shaping said auxiliary data signal according to a spectral shape of said primary data signal.

10. The method of claim 9, comprising the further steps of:

performing time domain analysis of said primary data signal; and

performing time domain synthesis responsive to said time domain analysis to provide a synthesis filter;

wherein said spectrally shaping step comprises the step of filtering said auxiliary data signal using said synthesis filter.

11. The method of claim 9, comprising the further steps of:

performing frequency domain analysis of said primary data signal; and

performing frequency domain synthesis responsive to said frequency domain analysis to provide a synthesis filter;

wherein said spectrally shaping step comprises the step of filtering said auxiliary data signal using said synthesis filter.

12. The method of claim 1, wherein:

said primary data signal comprises audio data; and

said desired signal-to-noise ratio is provided such that said auxiliary data signal is carried substantially inaudibly in said primary data signal.

25. The method of claim 1, wherein:

said auxiliary data signal comprises information indicative of a content of said primary data signal.

26. The method of claim 1, wherein:

said auxiliary data signal comprises information for effecting a copy protection scheme for said primary data signal.

27. The method of claim 1, wherein:

said auxiliary data signal is provided as white noise in said primary data signal.

13. An apparatus for adjusting the power of an auxiliary data signal which is carried with a primary data signal, comprising:

cross-term compensation (CTC) calculation means for providing a cross-term compensation signal which is indicative of a cross-correlation between said auxiliary data signal and said primary data signal; and

a power adjuster for adjusting the power of said auxiliary data signal according to said cross-term compensation signal.

14. The apparatus of claim 13, further comprising:

limiting means for limiting said cross-term compensation signal to a predetermined range.

15. The apparatus of claim 13, further comprising:

an average amplitude estimation means for determining an average amplitude of said primary data signal;

wherein;

said power adjuster is responsive to said average amplitude estimation means for adjusting the power of said auxiliary data signal according to said average amplitude.

16. The apparatus of claim 13, further comprising:

a floor limiter for floor-limiting the power adjustment of said auxiliary data signal.

17. The apparatus of claim 13, further comprising:

an average amplitude estimation means for determining an average amplitude of said primary data signal;

a multiplier for determining a product of said average amplitude and a desired signal-to-noise ratio of said auxiliary data signal in said primary data signal;

wherein;

said power adjuster is responsive to said multiplier for adjusting the power of said auxiliary data signal according to said product.

18. The apparatus of claim 17, wherein:

said cross-term compensation calculation means limits a magnitude of said cross-term compensation signal to a magnitude of said product of said average amplitude and said desired signal-to-noise ratio.

19. The apparatus of claim 13, further comprising:

a modulator for modulating a pseudorandom noise carrier by auxiliary information to provide said auxiliary data signal as a spread spectrum signal carrying said auxiliary information on a carrier portion thereof.

20. The apparatus of claim 13, wherein:

said auxiliary data signal is modulated according to a binary phase-shift keying (BPSK) technique.

21. The apparatus of claim 13, further comprising:

means for spectrally shaping said auxiliary data signal according to a spectral shape of said primary data signal.

22. The apparatus of claim 21, further comprising:

means for performing time domain analysis of said primary data signal; and

means for performing time domain synthesis responsive to said time domain analysis to provide a synthesis filter;

wherein said spectrally shaping means comprises said synthesis filter for filtering said auxiliary data signal to provide said spectral shaping thereof.

23. The apparatus of claim 21, further comprising:

means for performing frequency domain analysis of said primary data signal; and

means for performing frequency domain synthesis responsive to said frequency domain analysis to provide a synthesis filter;

wherein said spectrally shaping means comprises said synthesis filter for filtering said auxiliary data to provide said spectral shaping thereof.

24. The apparatus of claim 13, wherein:

said primary data signal comprises audio data; and

said auxiliary data signal is carried substantially inaudibly in said primary data signal.

28. The apparatus of claim 13, wherein:

said auxiliary data signal comprises information indicative of a content of said primary data signal.

29. The apparatus of claim 13, wherein:

said auxiliary data signal comprises information for effecting a copy protection scheme for said primary data signal.

30. The apparatus of claim 13, wherein:

said auxiliary data signal is provided as white noise in said primary data signal.

31. The apparatus of claim 13, wherein:

said power adjuster adjusts the power of said auxiliary data signal according to a desired signal-to-noise ratio to provide the power of said auxiliary data signal as a fraction of a power of said primary data signal.

32. A method for adjusting the power of an auxiliary data signal which is carried with a primary data signal, comprising the steps of:

providing a cross-term compensation signal which is indicative of a cross-correlation between said auxiliary data signal and said primary data signal;

adjusting a power of said auxiliary data signal according to said cross-term compensation signal; and

limiting said cross-term compensation signal to a predetermined range.

33. A method for adjusting the power of an auxiliary data signal which is carried with a primary data signal, comprising the steps of:

providing a cross-term compensation signal which is indicative of a cross-correlation between said auxiliary data signal and said primary data signal;

determining an average amplitude of said primary data signal; and

adjusting a power of said auxiliary data signal according to said cross-term compensation signal and said average amplitude.

34. A method for adjusting the power of an auxiliary data signal which is carried with a primary data signal, comprising the steps of:

providing a cross-term compensation signal which is indicative of a cross-correlation between said auxiliary data signal and said primary data signal;

adjusting a power of said auxiliary data signal according to said cross-term compensation signal; and

floor-limiting the power adjustment of said auxiliary data signal.

35. A method for adjusting the power of an auxiliary data signal which is carried with a primary data signal, comprising the steps of:

providing a cross-term compensation signal which is indicative of a cross-correlation between said auxiliary data signal and said primary data signal;

determining an average amplitude of said primary data signal; and

adjusting the power of said auxiliary data signal according to a product of said average amplitude and a desired signal-to-noise ratio, and according to said cross-term compensation signal.

36. The method of claim 35, comprising the further step of:

limiting a magnitude of said cross-term compensation signal to a magnitude of said product of said average amplitude and said desired signal-to-noise ratio.

37. A method for adjusting the power of an auxiliary data signal which is carried with a primary data signal, comprising the steps of:

providing a cross-term compensation signal which is indicative of a cross-correlation between said auxiliary data signal and said primary data signal;

adjusting a power of said auxiliary data signal according to said cross-term compensation signal; and

spectrally shaping said auxiliary data signal according to a spectral shape of said primary data signal.

38. An apparatus for adjusting the power of an auxiliary data signal which is carried with a primary data signal, comprising:

a cross-term compensation (CTC) calculator; and

a power adjuster associated with said CTC calculator;

wherein;

said CTC calculator provides a cross-term compensation signal which is indicative of a cross-correlation between said auxiliary data signal and said primary data signal; and

said power adjuster adjusts a power of said auxiliary data signal according to said cross-term compensation signal, and according to a desired signal-to-noise ratio to provide the power of said auxiliary data signal as a fraction of a power of said primary data signal.

39. The apparatus of claim 38, further comprising:

a limiter operatively associated with said CTC calculator;

said limiter being adapted to limit said cross-term compensation signal to a predetermined range.

40. The apparatus of claim 38, further comprising:

an estimator operatively associated with said CTC calculator;

said estimator being adapted to determine an average amplitude of said primary data signal;

wherein;

said power adjuster is responsive to said estimator for adjusting the power of said auxiliary data signal according to said average amplitude.

41. The apparatus of claim 38, further comprising:

a floor limiter operatively associated with said CTC calculator;

said floor limited being adapted to floor-limit the power adjustment of said auxiliary data signal.

42. The apparatus of claim 38, further comprising:

an estimator operatively associated with said CTC calculator;

said estimator being adapted to determine an average amplitude of said primary data signal; and

a multiplier coupled to said estimator;

wherein;

said multiplier is adapted to determine a product of said average amplitude and said desired signal-to-noise ratio; and

said power adjuster is responsive to said multiplier for adjusting the power of said auxiliary data signal according to said product.

43. The apparatus of claim 42, wherein:

said CTC calculator is adapted to limit a magnitude of said cross-term compensation signal to a magnitude of said product of said average amplitude and said desired signal-to-noise ratio.

44. The apparatus of claim 38, further comprising:

a modulator coupled to said second terminal;

said modulator being adapted to modulate said carrier by auxiliary information to provide said auxiliary data signal as a spread spectrum signal carrying said auxiliary information;

wherein said carrier is a pseudorandom noise carrier.

45. The apparatus of claim 38, wherein:

said auxiliary data signal is modulated according to a binary phase-shift keying (BPSK) technique.

46. The apparatus of claim 38, further comprising:

a shaping filter coupled to said first and second terminal;

said shaping filter being adapted to spectrally shape said auxiliary data signal according to a spectral shape of said primary data signal.

47. The apparatus of claim 46, further comprising:

means coupled to said first terminal for performing time domain analysis of said primary data signal; and

means for performing time domain synthesis responsive to said time domain analysis to provide a synthesis filter;

wherein said shaping filter comprises said synthesis filter for filtering said auxiliary data signal to provide said spectral shaping thereof.

48. The apparatus of claim 46, further comprising:

means coupled to said first terminal for performing frequency domain analysis of said primary data signal; and

means for performing frequency domain synthesis responsive to said frequency domain analysis to provide a synthesis filter;

wherein said shaping filter comprises said synthesis filter for filtering said auxiliary data to provide said spectral shaping thereof.

49. The apparatus of claim 38, wherein:

said primary data signal comprises audio data; and

said desired signal-to-noise ratio is provided such that said auxiliary data signal is carried substantially inaudibly in said primary data signal.

50. The apparatus of claim 38, wherein:

said auxiliary data signal comprises information indicative of a content of said primary data signal.

51. The apparatus of claim 38, wherein:

said auxiliary data signal comprises information for effecting a copy protection scheme for said primary data signal.

52. The apparatus of claim 38, wherein:

said auxiliary data signal is provided as white noise in said primary data signal.