Broadcast encoding system and method

• US 20020034224A1
• Filed: 06/15/2001
• Published: 03/21/2002
• Est. Priority Date: 07/16/1998
• Status: Active Grant

• Current Assignee: The Nielsen Company LLC (MOOD Media Corporation)
• Original Assignee: Nielsen Media Research, Inc. (Nielsen Holdings plc)
• Inventors: Srinivasan, Venugopal
• Granted Patent: US 6,504,870 B2
• Time in Patent Office: Days
• US Class Current: 375/240
• CPC Class Codes: H04H 20/31 using in-band signals, e.g. subsonic or cue signal
• CPC Class Codes: H04H 20/33 by plural channels
• CPC Class Codes: H04H 2201/50 characterised by the use of watermarks
• CPC Class Codes: H04H 60/37 for identifying segments of broadcast information, e.g. scenes or extracting programme ID
• CPC Class Codes: H04H 60/39 for identifying broadcast space-time use of Electronic Programme Guides H04H60/72

Abstract

An encoder is arranged to add a binary code bit to a block of a signal by selecting, within the block, (i) a reference frequency within the predetermined signal bandwidth, (ii) a first code frequency having a first predetermined offset from the reference frequency, and (iii) a second code frequency having a second predetermined offset from the reference frequency. The spectral amplitude at each of the first and second code frequencies may be respectively modified to be a maximum in a first neighborhood of frequencies extending about the first code frequency and a minimum in a second neighborhood of frequencies extending about the second code frequency. Alternatively, the phase of a signal component at one of the first and second code frequencies may be changed relative to a reference signal component.

Claims

1. A method for adding a binary code bit to a block of signal varying within a predetermined signal bandwidth, the method comprising the following steps:

a) selecting a reference frequency within the predetermined signal bandwidth, and associating therewith both a first code frequency having a first predetermined offset from the reference frequency and a second code frequency having a second predetermined offset from the reference frequency;

b) measuring the spectral power of the signal within the block in a first neighborhood of frequencies extending about the first code frequency and in a second neighborhood of frequencies extending about the second code frequency;

c) increasing the spectral power at the first code frequency so as to render the spectral power at the first code frequency a maximum in the first neighborhood of frequencies; and

,

d) decreasing the spectral power at the second code frequency so as to render the spectral power at the second code frequency a minimum in the second neighborhood of frequencies.

2. The method of claim 1 wherein the first and second code frequencies are selected according to the reference frequency, a frequency hop sequence number, and a predetermined shift index.

3. The method of claim 1 wherein the first and second code frequencies are selected according to the following equations:

4. The method of claim 1 wherein the reference frequency is selected in step a) according to the following steps:

a1) finding, within a predetermined portion of the bandwidth, a frequency at which the signal has a maximum spectral power; and

,

a2) adding a predetermined frequency shift to that frequency of maximum spectral power.

5. The method of claim 4 wherein the signal is an audio signal, wherein the predetermined portion of the bandwidth comprises a lower portion of the bandwidth extending from the lowest frequency by 2 kHz, and wherein the predetermined shift frequency is substantially equal to 5.

6. The method of claim 1 wherein the first and second code frequencies are selected according to the following equations:

7. The method of claim 1 wherein a synchronization block is added to the signal, and wherein the synchronization block is characterized by a triple tone portion.

8. The method of claim 1 wherein the signal has a spectral power which is a maximum in neighborhoods of the reference frequency, of the first code frequency, and of the second code frequency.

9. The method of claim 8 wherein a synchronization block is added to the signal, and wherein the synchronization block is characterized by a triple tone portion.

10. The method of claim 1 wherein the first and the second predetermined offsets have equal magnitudes but opposite signs.

11. The method of claim 1 wherein the first code frequency is greater than the reference frequency, and wherein the second code frequency is less than the reference frequency.

12. The method of claim 1 wherein the second code frequency is greater than the reference frequency, and wherein the first code frequency is less than the reference frequency.

13. The method of claim 1 wherein a plurality of binary code bits are added to the signal by repeating steps a)-d) a number of times.

15. The method of claim 14 wherein the first and second frequencies are selected according to the reference frequency, a frequency hop sequence number, and a predetermined shift index.

16. The method of claim 14 wherein the first and second code frequencies are selected according to the following equations:

17. The method of claim 14 wherein the reference frequency is selected in step a) according to the following steps:

a1) finding, within a predetermined portion of the bandwidth, a frequency at which the signal has a maximum spectral amplitude; and

,

a2) adding a predetermined frequency shift to that frequency of maximum spectral amplitude.

18. The method of claim 17 wherein the signal is an audio signal, wherein the predetermined portion of the bandwidth comprises a lower portion of the bandwidth extending from the lowest frequency by 2 kHz, and wherein the predetermined shift frequency is substantially equal to 5.

19. The method of claim 14 wherein the first and second code frequencies are selected according to the following equations:

20. The method of claim 14 wherein a synchronization block is added to the signal, and wherein the synchronization block is characterized by a triple tone portion.

21. The method of claim 14 wherein the signal has an spectral amplitude which is a maximum in neighborhoods of the reference frequency, of the first code frequency, and of the second code frequency.

22. The method of claim 21 wherein a synchronization block is added to the signal, and wherein the synchronization block is characterized by a triple tone portion.

23. The method of claim 14 wherein the first and the second predetermined offsets have equal magnitudes but opposite signs.

24. The method of claim 14 wherein the first code frequency is greater than the reference frequency, and wherein the second code frequency is less than the reference frequency.

25. The method of claim 14 wherein the second code frequency is greater than the reference frequency, and wherein the first code frequency is less than the reference frequency.

26. The method of claim 14 wherein a plurality of binary code bits are added to the signal by repeating steps a)-d) a number of times.

28. The method of claim 27 further comprising the step of finding a triple tone characterized in that (i) the received signal has a spectral amplitude at the reference frequency that is a local maximum within a frequency neighborhood of the reference frequency, (ii) the received signal has a spectral amplitude at the first code frequency that is a local maximum within a frequency neighborhood corresponding to the first code frequency, and (ii) the received signal has a spectral amplitude at the second code frequency that is a local maximum within a frequency neighborhood corresponding to the second code frequency.

29. The method of claim 27 wherein the first and second code frequencies are selected according to the reference frequency, a frequency hop sequence, and a predetermined shift index.

30. The method of claim 27 wherein the first and second code frequencies are selected according to the following steps:

finding, within a predetermined portion of the bandwidth, the frequency at which the spectral amplitude of the signal is a maximum; and

,

adding a predetermined frequency shift to that frequency of maximum spectral amplitude.

31. The method of claim 30 wherein the signal is an audio signal, wherein the predetermined portion of the bandwidth comprises a lower portion of the bandwidth extending from the lowest frequency thereof to 2 kHz thereabove, and wherein the predetermined shift frequency is substantially equal to 5.

32. The method of claim 27 wherein the first and the second predetermined frequency offsets have equal magnitudes but opposite signs.

14. A method for adding a binary code bit to a block of a signal having a spectral amplitude and a phase, both the spectral amplitude and the phase varying within a predetermined signal bandwidth, the method comprising the following steps:

a) selecting, within the block, (i) a reference frequency within the predetermined signal bandwidth, (ii) a first code frequency having a first predetermined offset from the reference frequency, and (iii) a second code frequency having a second predetermined offset from the reference frequency;

b) comparing the spectral amplitude of the signal near the first code frequency to the spectral amplitude of the signal near the second code frequency;

c) selecting a portion of the signal at one of the first and second code frequencies at which the corresponding spectral amplitude is smaller to be a modifiable signal component, and selecting a portion of the signal at the other of the first and second code frequencies to be a reference signal component; and

,

d) selectively changing the phase of the modifiable signal component so that it differs by no more than a predetermined amount from the phase of the reference signal component.

27. A method of reading a digitally encoded message transmitted with a signal having a time-varying intensity, the signal characterized by a signal bandwidth, the digitally encoded message comprising a plurality of binary bits, the method comprising the following steps:

a) selecting a reference frequency within the signal bandwidth;

b) selecting a first code frequency at a first predetermined frequency offset from the reference frequency and selecting a second code frequency at a second predetermined frequency offset from the reference frequency; and

,

c) finding which one of the first and second code frequencies has a spectral amplitude associated therewith that is a maximum within a corresponding frequency neighborhood and finding which one of the first and second code frequencies has a spectral amplitude associated therewith that is a minimum within a corresponding frequency neighborhood in order to thereby determine a value of a received one of the binary bits.

33. A method of reading a digitally encoded message transmitted with a signal having a spectral amplitude and a phase, the signal characterized by a signal bandwidth, the message comprising a plurality of binary bits, the method comprising the steps of:

a) selecting a reference frequency within the signal bandwidth;

b) selecting a first code frequency at a first predetermined frequency offset from the reference frequency and selecting a second code frequency at a second predetermined frequency offset from the reference frequency;

c) determining the phase of the signal within respective predetermined frequency neighborhoods of the first and the second code frequencies; and

,

d) determining if the phase at the first code frequency is within a predetermined value of the phase at the second code frequency and thereby determining a value of a received one of the binary bits.

34. The method of claim 33 further comprising the steps of finding a triple tone characterized in that the received signal has a spectral amplitude at the reference frequency that is a local maximum within the predetermined frequency neighborhood of the reference frequency and that the received signal has a spectral amplitude at each of the first and second code frequencies that is a local maximum within the respective predetermined frequency neighborhoods of the first and second code frequencies.

35. The method of claim 33 wherein the first and second frequencies are selected according to the reference frequency, a frequency hop sequence, and a predetermined shift index.

36. The method of claim 33 wherein the first and second frequencies are selected according to the following steps:

finding, within a predetermined portion of the bandwidth, the frequency at which the spectral amplitude of the signal is a maximum; and

,

adding a predetermined frequency shift to the frequency at which the spectral amplitude of the signal is a maximum.

37. The method of claim 36 wherein the signal is an audio signal, wherein the predetermined portion of the bandwidth comprises a lower portion of the bandwidth extending from the lowest frequency thereof to 2 kHz thereabove, and wherein the predetermined shift frequency is substantially equal to 5.

38. The method of claim 33 wherein the first and the second predetermined frequency offsets have equal magnitudes but opposite signs.

40. The encoder of claim 39 wherein the binary bit is a ‘

1’

bit.

41. The encoder of claim 39 wherein the binary bit is a ‘

0’

bit.

42. The encoder of claim 39 wherein the first and second code frequencies are selected according to the reference frequency, a frequency hop sequence number, and the first and second predetermined offsets.

43. The encoder of claim 39 wherein a synchronization block is added to the signal, and wherein the synchronization block is characterized by a triple tone portion.

44. The encoder of claim 39 wherein the first and the second predetermined offsets have equal magnitudes but opposite signs.

45. The encoder of claim 39 wherein a plurality of binary bits are added to the signal by repeating steps a)- d) a number of times.

47. The encoder of claim 46 wherein the binary bit is a ‘

1’

bit.

48. The encoder of claim 46 wherein the binary bit is ‘

0’

bit.

49. The encoder of claim 46 wherein the first and second code frequencies are selected according to the reference frequency, a frequency hop sequence number, and the first and second predetermined offsets.

50. The encoder of claim 46 wherein a synchronization block is added to the signal, and wherein the synchronization block is characterized by a triple tone portion.

51. The encoder of claim 46 wherein the first and the second predetermined offsets have equal magnitudes but opposite signs.

52. The encoder of claim 46 wherein a plurality of binary bits are added to the signal by repeating steps a)- d) a number of times.

39. An encoder arranged to add a binary bit of a code to a block of a signal having an intensity varying within a predetermined signal bandwidth comprising:

a selector arranged to select, within the block, (i) a reference frequency within the predetermined signal bandwidth, (ii) a first code frequency having a first predetermined offset from the reference frequency, and (iii) a second code frequency having a second predetermined offset from the reference frequency;

a detector arranged to detect a spectral amplitude of the signal in a first neighborhood of frequencies extending about the first code frequency and in a second neighborhood of frequencies extending about the second code frequency; and

,

a bit inserter arranged to insert the binary bit by increasing the spectral amplitude at the first code frequency so as to render the spectral amplitude at the first code frequency a maximum in the first neighborhood of frequencies and by decreasing the spectral amplitude at the second code frequency so as to render the spectral amplitude at the second code frequency a minimum in the second neighborhood of frequencies.

46. An encoder arranged to add a binary bit of a code to a block of a signal having a spectral amplitude and a phase, wherein both the spectral amplitude and the phase vary within a predetermined signal bandwidth, and wherein the encoder comprises:

a selector arranged to select, within the block, (i) a reference frequency within the predetermined signal bandwidth, (ii) a first code frequency having a first predetermined offset from the reference frequency, and (iii) a second code frequency having a second predetermined offset from the reference frequency;

a detector arranged to detect the spectral amplitude of the signal near the first code frequency and near the second code frequency;

a selector arranged to select the portion of the signal at one of the first and second code frequencies at which the corresponding spectral amplitude is smaller to be a modifiable signal component, and to select the portion of the signal at the other of the first and second code frequencies to be a reference signal component; and

,

a bit inserter arranged to insert the binary bit by selectively changing the phase of the modifiable signal component so that it differs by no more than a predetermined amount from the phase of the reference signal component.

53. A decoder arranged to decode a binary bit of a code from a block of a signal transmitted with a time-varying intensity comprising:

a selector arranged to select, within the block, (i) a reference frequency within the signal bandwidth, (iii) a first code frequency at a first predetermined frequency offset from the reference frequency, and (iii) a second code frequency at a second predetermined frequency offset from the reference frequency;

a detector arranged to detect a spectral amplitude within respective predetermined frequency neighborhoods of the first and the second code frequencies; and

,

a bit finder arranged to find the binary bit when one of the first and second code frequencies has a spectral amplitude associated therewith that is a maximum within its respective neighborhood and the other of the first and second code frequencies has a spectral amplitude associated therewith that is a minimum within its respective neighborhood.

54. The decoder of claim 53 wherein the signal contains a triple tone characterized in that (i) the received signal has a spectral amplitude at the reference frequency that is a local maximum within the predetermined frequency neighborhood of the reference frequency, (ii) the received signal has a spectral amplitude at the first code frequency that is a local maximum within a predetermined frequency neighborhood corresponding to the first code frequency, and (ii) the received signal has a spectral amplitude at the second code frequency that is a local maximum within a predetermined frequency neighborhood corresponding to the second code frequency.

55. The decoder of claim 53 wherein the selector is arranged to select the first and second code frequencies according to the reference frequency, a frequency hop sequence, and the first and second predetermined offsets.

56. The decoder of claim 53 wherein the first and the second frequency offsets have equal magnitudes but opposite signs.

57. The decoder of claim 53 wherein the decoded binary bit is a ‘

1’

bit.

58. The decoder of claim 53 wherein the decoded binary bit is a ‘

1’

bit.

60. The decoder of claim 59 wherein the signal contains a triple tone characterized in that (i) the received signal has a spectral amplitude at the reference frequency that is a local maximum within a predetermined frequency neighborhood of the reference frequency, (ii) the received signal has a spectral amplitude at the first code frequency that is a local maximum within the predetermined frequency neighborhood corresponding to the first code frequency, and (ii) the received signal has a spectral amplitude at the second code frequency that is a local maximum within the predetermined frequency neighborhood corresponding to the second code frequency.

61. The decoder of claim 59 wherein the selector is arranged to select the first and second code frequencies according to the reference frequency, a frequency hop sequence, and the first and second predetermined offsets.

62. The decoder of claim 59 wherein the first and the second frequency offsets have equal magnitudes but opposite signs.

63. The decoder of claim 59 wherein the decoded binary bit is a ‘

1’

bit.

64. The decoder of claim 59 wherein the decoded binary bit is a ‘

0’

bit.

59. A decoder arranged to decode a binary bit of a code from a block of a signal transmitted with a time-varying intensity comprising:

a selector arranged to select, within the block, (i) a reference frequency within the signal bandwidth, (ii) a first code frequency at a first predetermined frequency offset from the reference frequency, and (iii) a second code frequency at a second predetermined frequency offset from the reference frequency;

a detector arranged to detect the phase of the signal within respective predetermined frequency neighborhoods of the first and the second code frequencies; and

,

a bit finder arranged to find the binary bit when the phase at the first code frequency is within a predetermined value of the phase at the second code frequency.

65. An encoding arrangement for encoding a signal with a code, wherein the signal has a video portion and an audio portion, the encoding arrangement comprising:

an encoder arranged to encode one of the portions of the signal; and

,

a compensator arranged to compensate for any relative delay between the video portion and the audio portion caused by the encoder.

66. The encoding arrangement of claim 65 wherein the encoder is an audio encoder arranged to encode the audio portion of the signal with an audio code, and wherein the compensator is arranged to compensate for any relative delay between the video portion and the audio portion caused by the audio encoder.

67. The encoding arrangement of claim 66 further comprising a video encoder arranged to encode the video portion of the signal with a video code.

68. The encoder of claim 65 wherein the compensator comprises a delay arranged to delay the video portion relative to the audio portion in order to compensate for any delay between the video portion and the audio portion caused by the encoder.

69. The encoder of claim 65 wherein the compensator comprises a delay arranged to delay one of the portions of the signal relative to the other portion in order to compensate for any delay between the video portion and the audio portion caused by the encoder.

70. A method of reading a data element from a received signal comprising the steps of:

a) computing a Fourier Transform of a first block of n samples of the received signal;

b) testing the first block for the data element;

c) setting an array element SIS[a] of an SIS array to a predetermined value if the data element is found in the first block;

d) updating the Fourier Transform of the first block of n samples for a second block of n samples of the received signal, wherein the second block differs from the first block by k samples, and wherein k<

n;

e) testing the second block for the data element; and

,

f) setting an array element SIS[a+1] of the SIS array to the predetermined value if the data element is found in the first block.

71. The method of claim 70 wherein step d) is performed according to the following equations:

72. The method of claim 70 wherein step d) is limited to a range of frequency indices of interest.

73. The method of claim 70 wherein steps d)-f) are repeated for a predetermined number m of data elements.

74. The method of claim 73 further comprising the following steps:

g) comparing the predetermined number m of data elements are compared to a reference;

h) setting an integer of a raw data array DA to a value dependent upon step g).

75. The method of claim 74 repeating steps d)-h) until a predetermined of data elements are found.

76. A method for adding a binary code bit to a block of a signal varying within a predetermined signal bandwidth, the method comprising the following steps:

a) selecting a reference frequency within the predetermined signal bandwidth, and associating therewith both a first code frequency having a first predetermined offset from the reference frequency and a second code frequency having a second predetermined offset from the reference frequency;

b) measuring the spectral power of the signal within the block in a first neighborhood of frequencies extending about the first code frequency and in a second neighborhood of frequencies extending about the second code frequency, wherein the first frequency has a spectral amplitude, and wherein the second frequency has a spectral amplitude;

c) swapping the spectral amplitude of the first code frequency with a spectral amplitude of a frequency having a maximum amplitude in the first neighborhood of frequencies while retaining a phase angle at both the first frequency and the frequency having the maximum amplitude in the first neighborhood of frequencies; and

,

d) swapping the spectral amplitude of the second code frequency with a spectral amplitude of a frequency having a minimum amplitude in the second neighborhood of frequencies while retaining a phase angle at both the second frequency and the frequency having the maximum amplitude in the second neighborhood of frequencies.