Simultaneous transmission of data and audio signals by means of perceptual coding

• US 5,404,377 A
• Filed: 04/08/1994
• Issued: 04/04/1995
• Est. Priority Date: 04/08/1994
• Status: Expired due to Term

• Current Assignee: Intel Corporation
• Original Assignee: Donald W. Moses
• Inventors: Moses, Donald W.
• Primary Examiner(s): Swann, Tod R.
• Application Number:
  US08/224,906
• Time in Patent Office: 361 Days
• Field of Search: 375/1, 380/34, 395/2.11, 395/2.12, 395/2.41
• US Class Current: 375/145
• 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: H04M 11/06 Simultaneous speech and data transmission, e.g. telegraphic transmission over the same conductors

Abstract

A communication system for simultaneously transmitting data and audio signals via a conventional audio communications channel using perceptual coding techniques is disclosed. In a preferred embodiment, a first artificial neural network (NN) at an encoder monitors an audio channel to detect "opportunities" to insert the data signal such that the inserted signals are masked by the audio signal, as defined by the "perceptual entropy envelope" of the audio signal. Under the control of the first NN a data signal containing, for example, an ID or serial number, is encoded as one or more whitened direct sequence spread spectrum signals and/or a narrowband FSK data signal and transmitted at the time, frequency and level determined by the first NN such that the data signal is masked by the audio signal. The audio signal is combined with the spread spectrum and/or the FSK data signal(s) to form a composite signal, which is transmitted to one or more receiving locations via the audio channel. A decoder at each of the receiving locations comprises preprocessing circuitry, receiver sync circuitry and FSK decoder circuitry, as well as a second NN, which NN uses pattern and signature recognition techniques to perform block decoding, bit deinterleaving and acquisition confirm functions to recover the encoded ID or serial number.

Claims

1. Apparatus for encoding a data signal to be transmitted simultaneously with an audio signal such that said encoded data signal is masked by said audio signal, the apparatus comprising:

means for monitoring said audio signal to determine a perceptual entropy envelope thereof, said monitoring means generating control signals indicative of said determined perceptual entropy envelope;

means responsive to said control signals for encoding said data signal as an frequency shift key (FSK) modulated signal and for outputting said FSK modulated signal at times, frequencies and levels falling within said determined perceptual entropy envelope of said audio signal such that when combined with said audio signal, said FSK modulated signal is masked by said audio signal; and

means for combining said audio signal with said FSK modulated signal to form a composite signal.

2. The apparatus of claim 1 further comprising means responsive to said control signals for encoding said data signal as a spread spectrum signal and for outputting said spread spectrum signal at times, frequencies and levels falling within said detected perceptual entropy envelope of said audio signal such that when combined with said audio signal, said transmitted spread spectrum signal is masked by said audio signal, wherein said means for combining further combines said spread spectrum signal with said FSK modulated signal and said audio signal.

3. The apparatus of claim 2 wherein said spread spectrum encoding means comprises:

means for merging said data signal modulo-2 with a pseudo noise (PN) code; and

means for adding a PN header signal to each frame of said data signal.

4. The apparatus of claim 1 wherein said monitoring means comprises an artificial neural network.

5. The apparatus of claim 4 wherein said monitoring means further comprises:

a clock control circuit connected to an first output of said neural network for generating control signals to control the transmission frequency of said encoded data signal;

a level control circuit connected to an second output of said neural network for generating control signals to control the level of said encoded data signal; and

a burst timing circuit connected to an third output of said neural network for generating control signals to control the timing of transmission of said encoded data signal.

6. The apparatus of claim 1 wherein said monitoring means comprises means for determining the perceptual entropy envelope of said audio signal only in a first group of subbands, wherein each subband in said first group of subbands is proximate to a selected subband, said determining means generating control signals to said FSK modulating means for causing said FSK modulating means to output said FSK modulated signal in said selected subband such that it is masked by said audio signal in at least one subband in said first group of subbands and such that it is the strongest signal in said selected subband.

7. The apparatus of claim 1 wherein said data signal contains information for identifying at least one of a broadcaster, a program, a network, or an advertiser.

8. The apparatus of claim 1 further comprising:

means for generating said data signal;

means connected to receive said data signal from said generating means for encoding said data signal to withstand error hits during transmission using bit interleaving and block encoding techniques and for supplying said data signal to said FSK encoding means.

9. The apparatus of claim 1 further comprising means for transmitting said composite signal via an audio channel.

10. The apparatus of claim 1 further comprising means for recording said composite signal on a data storage medium.

11. Apparatus for encoding a data signal to be transmitted simultaneously with an audio signal such that said data signal is masked by said audio signal, the apparatus comprising:

means for monitoring said audio signal to determine a perceptual entropy envelope thereof, said monitoring means generating control signals indicative of said determined perceptual entropy envelope;

means responsive to said control signals for encoding said data signal as a spread spectrum signal and for outputting said spread spectrum signal at times, frequencies and levels falling within said determined perceptual entropy envelope of said audio signal such that when combined with said audio signal, said spread spectrum signal is masked by said audio signal; and

means for combining said audio signal with said spread spectrum signal to form a composite signal.

12. The apparatus of claim 11 wherein said encoding means comprises:

means for merging said data signal modulo-2 with a pseudo noise (PN) code; and

means for adding a PN header signal to each frame of said data signal.

13. The apparatus of claim 11 further comprising means responsive to said control signals for frequency shift key (FSK) modulating said data signal and for outputting said FSK modulated signal at times, frequencies and levels falling within said detected perceptual entropy envelope of said audio signal such that when combined with said audio signal, said FSK modulated signal is masked by said audio signal, wherein said means for combining further combines said spread spectrum signal with said spread spectrum signal and said audio signal.

14. The apparatus of claim 11 wherein said monitoring means comprises an artificial neural network.

15. The apparatus of claim 14 wherein said monitoring means further comprises:

a clock control circuit connected to an first output of said neural network for generating control signals to control the transmission frequency and processing gain of said spread spectrum signal;

a level control circuit connected to an second output of said neural network for generating control signals to control the level of said spread spectrum signal; and

a burst timing circuit connected to an third output of said neural network for generating control signals to control the timing of transmission of said spread spectrum signal.

16. The apparatus of claim 11 further comprising:

means for generating said data signal;

means connected to receive said data signal from said generating means for encoding said data signal to withstand error hits during transmission using block encoding and bit interleaving techniques and for supplying said data signal to said FSK modulation means.

17. The apparatus of claim 11 wherein said data signal contains information for identifying at least one of a broadcaster, a program, a network, or an advertiser.

18. Apparatus for decoding a data signal containing an information code transmitted simultaneously with an audio signal such that said data signal is masked by said audio signal, wherein prior to transmission, said data signal is encoded as frequency shift key (FSK) modulated signal, a direct sequence spread spectrum (DSSS) signal or both, said encoded data signal being combined with said audio signal to form a composite signal, the apparatus comprising:

means for receiving said composite signal from an audio channel;

means connected to said receiving means for filtering said received composite signal, wherein passband parameters of said filtering means are dictated by the bandwidth of said audio channel;

means connected to an output of said filtering means for demodulating said FSK modulated signal if said encoded data signal comprises an FSK modulated signal; and

means connected to said filtering means output for decoding said DSSS signal if said encoded data signal comprises a DSSS signal.

19. The decoder of claim 18 wherein said encoded data signal is transmitted in a partial response mode and first and second fuzzy logic forms of said data signal are output from said FSK demodulating means and said DSSS decoding means, respectively, the decoder further comprising means connected to an output of said FSK demodulating means and to an output of said DSSS decoding means for recovering said information code from said first and second fuzzy logic data signals using pattern recognition techniques.

20. The apparatus of claim 18 wherein said means for decoding said DSSS signal comprises:

means for synchronizing the phase of a clock signal with the phase of said DSSS signal and for outputting said synchronized clock signal; and

means connected to receive said synchronized clock signal for merging said DSSS signal modulo-2 with a pseudo-noise (PN) code used to encode the data signal.

21. The apparatus of claim 18 further comprising a data storage unit connected to an output of said FSK demodulating means and to an output of said DSSS decoding means.

22. The apparatus of claim 19 further comprising a data storage unit connected to an output of said recovering means for temporarily storing said recovered information code.

23. The apparatus of claim 19 wherein said recovering means comprises an artificial neural network.

24. A communications system for enabling the simultaneous transmission of a data signal and an audio signal via an audio channel such that said data signal is masked by said audio signal, the system comprising:

means for monitoring said audio signal to determine a perceptual entropy envelope thereof, said monitoring means generating control signals indicative of said determined perceptual entropy envelope;

means responsive to said control signals for encoding said data signal as an frequency shift key (FSK) modulated signal and for outputting said FSK modulated signal at times, frequencies and levels falling within said determined perceptual entropy envelope of said audio signal such that when combined with said audio signal, said FSK modulated signal is masked by said audio signal;

means responsive to said control signals for encoding said data signal as a spread spectrum signal and for outputting said spread spectrum signal at times, frequencies and levels falling within said determined perceptual entropy envelope of said audio signal such that when combined with said audio signal, said spread spectrum signal is masked by said audio signal;

means for combining said audio signal, said FSK modulated signal and said spread spectrum signal to form a composite signal;

means for transmitting said composite signal via said audio channel;

means for receiving said transmitted composite signal from said audio channel;

means connected to said receiving means for demodulating said FSK modulated signal of said received composite signal;

means connected to said receiving means for decoding said spread spectrum signal of said received composite signal; and

means connected to an output of said demodulating means and to an output of said decoding means for recovering an information code from said demodulated FSK signal and said decoded spread spectrum signal using pattern recognition techniques.

25. The system of claim 24 wherein said encoded data signal is transmitted in a partial response mode, such that said FSK demodulating means and said DSSS decoding means output first and second fuzzy logic forms of said data signal, respectively, the system further comprising means connected to outputs of said FSK demodulating means and said DSSS decoding means for recovering said information code from said first and second fuzzy logic data signals using pattern recognition techniques.

26. The system of claim 24 further comprising means connected to said receiving means for filtering said received composite signal, wherein the passband parameters of said filtering means are dictated by the bandwidth of said audio channel.

27. The system of claim 24 wherein said monitoring means comprises an artificial neural network.

28. The system of claim 27 wherein said monitoring means further comprises:

a clock control circuit connected to an first output of said neural network for generating control signals to control the transmission frequency and processing gain of said FSK modulated signal and said spread spectrum signal;

a level control circuit connected to an second output of said neural network for generating control signals to control the level of said FSK modulated signal and said spread spectrum signal; and

a burst timing circuit connected to an third output of said neural network for generating control signals to control the timing of transmission of said FSK modulated signal and said spread spectrum signal.

29. The system of claim 24 wherein said monitoring means comprises means for determining the perceptual entropy envelope of said audio signal only in a first group of subbands, wherein each subband in said first group of subbands is proximate to a selected subband, said determining means generating control signals to said FSK modulating means for causing said FSK modulating means to output said FSK modulated signal in said selected subband such that it is masked by said audio signal in at least one subband in said first group of subbands and such that it is the strongest signal in said selected subband.

30. The system of claim 24 further comprising:

means for generating said data signal;

means connected to receive said data signal from said generating means for encoding said data signal to withstand error hits during transmission using bit interleaving and block encoding techniques and for supplying said data signal to said FSK encoding means.

31. The system of claim 24 wherein said spread spectrum encoding means comprises:

means for merging said data signal modulo-2 with a pseudo noise (PN) code; and

means for adding a PN header signal to each frame of said data signal.

32. The system of claim 24 wherein said means for decoding said DSSS signal comprises:

means for synchronizing the phase of a clock signal with the phase of said DSSS signal and for outputting said synchronized clock signal; and

means connected to receive said synchronized clock signal for merging said DSSS signal modulo-2 with said pseudo-noise (PN) code.

33. The system of claim 24 wherein said recovering means comprises an artificial neural network.

34. The system of claim 24 further comprising a data storage unit connected to an output of said recovering means for temporarily storing said information code.

35. The system of claim 24 wherein said data signal contains information for identifying at least one of a broadcaster, a program, a network, or an advertiser.

36. A method of encoding a data signal to be transmitted simultaneously with an audio signal such that said encoded data signal is masked by said audio signal, the method comprising:

monitoring said audio signal to determine a perceptual entropy envelope thereof;

generating control signals indicative of said determined perceptual entropy envelope;

responsive to said control signals, encoding said data signal as an frequency shift key (FSK) modulated signal;

outputting said FSK modulated signal at times, frequencies and levels falling within said determined perceptual entropy envelope of said audio signal such that when combined with said audio signal, said FSK modulated signal is masked by said audio signal; and

combining said audio signal with said FSK modulated signal to form a composite signal.

37. The method of claim 36 further comprising:

responsive to said control signals, encoding said data signal as a spread spectrum signal; and

outputting said spread spectrum signal at times, frequencies and levels falling within said determined perceptual entropy envelope of said audio signal such that when combined with said audio signal, said spread spectrum signal is masked by said audio signal;

wherein said combining further comprises combining said spread spectrum signal with said FSK modulated signal and said audio signal.

38. The method of claim 37 wherein said spread spectrum encoding comprises:

merging said data signal modulo-2 with a pseudo noise (PN) code; and

adding a PN header signal to each frame of said data signal.

39. The method of claim 36 wherein said generating comprises:

generating control signals to control the transmission frequency of said encoded data signal;

generating control signals to control the level of said encoded data signal; and

generating control signals to control the timing of transmission of said encoded data signal.

40. The method of claim 36 wherein said monitoring further comprises:

determining the perceptual entropy envelope of said audio signal only in a first group of subbands, wherein each subband in said first group of subbands is proximate to a selected subband; and

generating control signals to said FSK modulating means for causing said FSK modulating means to output said FSK modulated signal in said selected subband such that it is masked by said audio signal in at least one subband in said first group of subbands and such that it is the strongest signal in said selected subband.

41. The method of claim 36 further comprising:

generating said data signal;

encoding said data signal to withstand error hits during transmission using bit interleaving and block encoding techniques prior to said FSK encoding.

42. The method of claim 36 further comprising transmitting said composite signal via an audio channel.

43. The method of claim 36 further comprising recording said composite signal on a data storage medium.

44. The method of claim 36 wherein said monitoring is performed by an artificial neural network.

45. The method of claim 36 wherein said data signal contains information for identifying at least one of a broadcaster, a program, a network, or an advertiser.

49. The method of claim 43 wherein said monitoring further comprises:

generating control signals to control the transmission frequency and processing gain of said spread spectrum signal;

generating control signals to control the level of said spread spectrum signal; and

generating control signals to control the timing of transmission of said spread spectrum signal.

46. A method of encoding a data signal to be transmitted simultaneously with an audio signal such that said data signal is masked by said audio signal, the method comprising:

monitoring said audio signal to determine a perceptual entropy envelope thereof;

responsive to said monitoring, generating control signals indicative of said determined perceptual entropy envelope;

responsive to said control signals, encoding said data signal as a spread spectrum signal;

outputting said spread spectrum signal at times, frequencies and levels falling within said determined perceptual entropy envelope of said audio signal such that when combined with said audio signal, said spread spectrum signal is masked by said audio signal; and

combining said audio signal with said spread spectrum signal to form a composite signal.

47. The method of claim 46 wherein said encoding comprises:

merging said data signal modulo-2 with a pseudo noise (PN) code; and

adding a PN header signal to each frame of said data signal.

48. The method of claim 46 further comprising, responsive to said control signals, frequency shift key (FSK) modulating said data signal and for outputting said FSK modulated signal at times, frequencies and levels falling within said determined perceptual entropy envelope of said audio signal such that when combined with said audio signal, said FSK modulated signal is masked by said audio signal, wherein said means for combining further combines said spread spectrum signal with said spread spectrum signal and said audio signal.

50. A method of decoding a data signal containing an information code transmitted simultaneously with an audio signal such that said data signal is masked by said audio signal, wherein prior to transmission, said data signal is encoded as frequency shift key (FSK) modulated signal, a direct sequence spread spectrum (DSSS) signal or both, said encoded data signal being combined with said audio signal to form a composite signal, the method comprising:

receiving said composite signal from an audio channel;

filtering said received composite signal, wherein passband parameters of said filtering are dictated by the bandwidth of said audio channel;

demodulating said FSK modulated signal if said encoded data signal comprises an FSK modulated signal; and

decoding said DSSS signal if said encoded data signal comprises a DSSS signal.

51. The method of claim 50 wherein said encoded data signal is transmitted in partial response mode, said FSK demodulating and said DSSS decoding produce first and second fuzzy logic forms of said data signal, respectively, the method further comprising recovering said information code from said first and second fuzzy logic data signals using pattern recognition techniques.

52. The method of claim 50 further comprising temporarily storing said recovered information code.

53. The method of claim 50 wherein said decoding said DSSS signal comprises:

synchronizing the phase of a clock signal with the phase of said DSSS signal and outputting said synchronized clock signal; and

merging said DSSS signal modulo-2 with a pseudo-noise (PN) code used to encode the data signal.

54. A method of enabling the simultaneous transmission of a data signal and an audio signal via an audio channel such that said data signal is masked by said audio signal, the method comprising:

monitoring said audio signal to determine a perceptual entropy envelope thereof, said monitoring means generating control signals indicative of said determined perceptual entropy envelope;

responsive to said control signals, encoding said data signal as an frequency shift key (FSK) modulated signal and outputting said FSK modulated signal at times, frequencies and levels falling within said determined perceptual entropy envelope of said audio signal such that when combined with said audio signal, said FSK modulated signal is masked by said audio signal;

responsive to said control signals, encoding said data signal as a spread spectrum signal and outputting said spread spectrum signal at times, frequencies and levels falling within said determined perceptual entropy envelope of said audio signal such that when combined with said audio signal, said spread spectrum signal is masked by said audio signal;

combining said audio signal, said FSK modulated signal and said spread spectrum signal to form a composite signal;

transmitting said composite signal via said audio channel;

receiving said transmitted composite signal from said audio channel;

demodulating said FSK modulated signal of said received composite signal;

decoding said spread spectrum signal of said received composite signal; and

recovering an information code from said demodulated FSK modulated signal and said decoded spread spectrum signal using pattern recognition techniques.

55. The method of claim 54 further comprising filtering said received composite signal, wherein passband parameters of said filtering are dictated by the bandwidth of said audio channel.

56. The method of claim 54 wherein said spread spectrum encoding comprises:

merging said data signal modulo-2 with a pseudo noise (PN) code; and

adding a PN header signal to each frame of said data signal.

57. The system of claim 54 wherein said monitoring further comprises:

determining the perceptual entropy envelope of said audio signal only in a first group of subbands, wherein each subband in said first group of subbands is proximate to a selected subband; and

responsive to said determining, generating control signals to said FSK modulating means for causing said FSK modulating means to output said FSK modulated signal in said selected subband such that it is masked by said audio signal in at least one subband in said first group of subbands and such that it is the strongest signal in said selected subband.

58. The method of claim 54 further comprising temporarily storing said information code.

59. The system of claim 54 wherein said decoding said spread spectrum signal comprises:

synchronizing the phase of a clock signal with the phase of said spread spectrum signal and outputting said synchronized clock signal; and

merging said DSSS signal modulo-2 with said pseudo-noise (PN) code.