Signal detector employing coherent integration

• US 6,297,771 B1
• Filed: 06/07/2000
• Issued: 10/02/2001
• Est. Priority Date: 03/30/1999
• Status: Expired due to Term

• Current Assignee: CSR Technology Incorporated (Qualcomm, Inc.)
• Original Assignee: Conexant Systems Incorporated (Synaptics Incorporated)
• Inventors: Gronemeyer, Steven A.
• Primary Examiner(s): PHAN, DAO LINDA
• Application Number:
  US09/588,958
• Time in Patent Office: 482 Days
• Field of Search: 342/89, 342/357.06, 342/378, 342/382, 701/213, 375/200, 375/208, 375/367
• US Class Current: 342/378
• CPC Class Codes: G01S 1/045 Receivers
• CPC Class Codes: G01S 19/256 relating to timing, e.g. time of week, code phase, timing offset
• CPC Class Codes: G01S 19/29 carrier including Doppler, related G01S19/246 takes precedence
• CPC Class Codes: G01S 19/30 code related G01S19/246 takes precedence

Abstract

A signal detector is provided in which complex samples of a received signal are multiplied by data representative of a hypothesis, and the resulting product data is coherently integrated over a desired duration to provide correlation data representative of the level of correlation between the hypothesis and the signal. In one embodiment, the signal detector is part of a GPS receiver.

Claims

1. A signal detector, comprising:

a receiver configured to detect at least one signal of interest perturbed by noise and configured to detect at least one reference signal;

a multiplier configured to derive data from a segment of the at least one signal of interest, the multiplier configured to multiply the data with data representative of at least one hypothesis, and the multiplier configured to provide product data representative of the segment and the at least one hypothesis; and

a coherent integrator configured to integrate the product data over a duration of time, and configured to derive correlation data useful for detecting the signal of interest.

2. The signal detector of claim 1, wherein the signal of interest is a plurality of successive frames separated by a frame boundary, and wherein each the segment having an ending portion of a first frame of the plurality of frames, a beginning portion of a second frame successive to the first frame, and the frame boundary between the first frame and the second frame.

3. The signal detector of claim 2, wherein the at least one reference signal determines the location of the frame boundary.

4. The signal detector of claim 2, wherein the at least one reference signal provides bit synchronization information associated with the signal of interest.

5. The signal detector of claim 2, wherein the at least one reference signal provides information specifying the location of data epochs associated with the signal of interest.

6. The signal detector of claim 5, wherein the at least one reference signal provides information determining phase reversals of the data epochs.

7. The signal detector of claim 2, wherein a phase of the beginning portion of the second frame is in a phase reversal at the frame boundary with respect to the ending portion of the second frame.

8. The signal detector of claim 7, further comprising a phase detector configured to detect the phase reversal, and wherein the coherent integrator is responsive to the detection of the phase reversal and is configured to adjust the beginning portion of the second frame to allow coherent integration to proceed across the frame boundary.

9. The signal detector of claim 7, further comprising a phase detector configured to detect the phase reversal, and wherein the coherent integrator is responsive to the detection of the phase reversal and is configured to flip the sign of the data residing in the beginning portion of the second frame to allow coherent integration to proceed across the frame boundary.

10. The signal detector of claim 7, further comprising a frame boundary detector configured to detect the frame boundary, wherein the coherent integrator, responsive to the detection of the frame boundary, is configured to noncoherently integrate the ending portion of the first frame and the beginning portion of the second frame.

11. The signal detector of claim 7, further comprising a frame boundary detector configured to detect the frame boundary, wherein the coherent integrator, responsive to the detection of a frame boundary, is configured to derive first correlation data by coherently integrating the product data across the frame boundary under a first hypothesis, and to derive second correlation data by coherently integrating the product data across the frame boundary under a second hypothesis.

12. The signal detector of claim 11, further comprising a circuitry selecting one of the first correlation data and the second correlation data based on which of the first hypotheses and the second hypothesis is more likely.

13. The signal detector of claim 11, wherein the first hypothesis assumes the phase of the beginning portion of the second frame is unchanged from the phase of the ending portion of the first frame across the frame boundary, and the second hypothesis assumes the phase of the beginning portion of the second frame flips the sign of the phase across the frame boundary with respect to the phase of the ending portion of the first frame.

14. The signal detector of claim 1, wherein the receiver is an RF receiver.

15. The signal detector of claim 1, wherein the signal of interest is a carrier signal modulated with a repeating pseudo-noise (PN) code.

16. The signal detector of claim 1, wherein the noise is pseudo-noise.

17. The signal detector of claim 1, wherein the segment has complex data having a real component and an imaginary component, and wherein the complex data is processed by the multiplier and the coherent integrator through complex addition and complex multiplication so that the correlation data is complex.

18. The signal detector of claim 1, wherein the segment has complex data having a magnitude component and a phase component, and wherein the complex data is processed by the multiplier and the coherent integrator through complex addition and complex multiplication so that the correlation data is complex.

19. The signal detector of claim 1, further comprising a hypothesis generator for generating the at least one hypotheses.

20. The signal detector of claim 1, further comprising a processor for receiving and analyzing the correlation data.

21. The signal detector of claim 1, wherein the reference signal is generated by a cellular network.

22. The signal detector of claim 1, wherein the reference signal is generated by a PCS phone network.

23. The signal detector of claim 1, wherein the receiver is a global positioning system (GPS) receiver.

24. The signal detector of claim 1, wherein the at least one signal of interest is generated by a corresponding at least one global positioning system (GPS) satellite.

25. The signal detector of claim 24, wherein the signal of interest is generated by the GPS satellite is not tracked continuously.

26. The signal detector of claim 1, wherein the receiver detects a parameter of the signal of interest.

27. A signal detector, comprising:

means for receiving at least one signal of interest perturbed by noise;

means for detecting at least one reference signal;

means for deriving data from a segment of the at least one signal of interest;

means for multiplying the data with data representative of at least one hypothesis;

means for providing product data representative of the segment and the at least one hypothesis;

means for integrating the product data over a duration of time; and

means for deriving correlation data useful for detecting the signal of interest.

28. The signal detector of claim 27, wherein the signal of interest is a plurality of successive frames separated by a frame boundary, and wherein each the segment having an ending portion of a first frame of the plurality of frames, a beginning portion of a second frame successive to the first frame, and the frame boundary between the first frame and the second frame.

29. The signal detector of claim 28, wherein the at least one reference signal determines the location of the frame boundary.

30. The signal detector of claim 28, wherein the at least one reference signal provides bit synchronization information associated with the signal of interest.

31. The signal detector of claim 28, wherein the at least one reference signal provides information specifying the location of data epochs associated with the signal of interest.

32. The signal detector of claim 31, wherein the at least one reference signal provides information determining phase reversals of the data epochs.

33. The signal detector of claim 28, wherein a phase of the beginning portion of the second frame is in a phase reversal at the frame boundary with respect to the ending portion of the second frame.

34. The signal detector of claim 33, further comprising a means for detecting the phase reversal, wherein the means for integrating is responsive to the means for detecting the phase reversal, and wherein the means for integrating adjusts the beginning portion of the second frame to allow coherent integration to proceed across the frame boundary.

35. The signal detector of claim 33, further comprising a means for detecting the phase reversal, wherein the means for integrating is responsive to the detection of the phase reversal, and wherein the means for integrating flips the sign of the data residing in the beginning portion of the second frame to allow coherent integration to proceed across the frame boundary.

36. The signal detector of claim 33, further comprising a means for detecting the frame boundary, wherein the means for integrating is responsive to the detection of the frame boundary, and wherein the means for integrating integrates the ending portion of the first frame and the beginning portion of the second frame.

37. The signal detector of claim 33, further comprising a means for detecting the frame boundary, wherein the means for integrating is responsive to the detection of a frame boundary, and wherein the means for integrating derives first correlation data by coherently integrating the product data across the frame boundary under a first hypothesis, and derives second correlation data by coherently integrating the product data across the frame boundary under a second hypothesis.

38. The signal detector of claim 37, further comprising a means for selecting one of the first correlation data and the second correlation data based on which of the first hypotheses and the second hypothesis is more likely.

39. The signal detector of claim 38, wherein the first hypothesis assumes the phase of the beginning portion of the second frame is unchanged from the phase of the ending portion of the first frame across the frame boundary, and the second hypothesis assumes the phase of the beginning portion of the second frame flips the sign of the phase across the frame boundary with respect to the phase of the ending portion of the first frame.

40. The signal detector of claim 27, wherein the signal of interest is a carrier signal modulated with a repeating pseudo-noise (PN) code.

41. The signal detector of claim 27, wherein the noise is pseudo-noise.

42. The signal detector of claim 27, wherein the segment has complex data having a real component and an imaginary component, wherein the complex data is processed by the means for multiplying, and wherein the means for integrating integrates through complex addition and complex multiplication so that the correlation data is complex.

43. The signal detector of claim 27, wherein the segment has complex data having a magnitude component and a phase component, wherein the complex data is processed by the means for multiplying, and wherein the means for integrating integrates through complex addition and complex multiplication so that the correlation data is complex.

44. The signal detector of claim 27, further comprising a means for hypothesis generation for generating the at least one hypotheses.

45. The signal detector of claim 27, wherein the reference signal is generated by a cellular network.

46. The signal detector of claim 27, wherein the reference signal is generated by a PCS phone network.

47. The signal detector of claim 27, wherein the means for receiving receives global positioning system (GPS) signals.

48. The signal detector of claim 27, wherein the at least one signal of interest is generated by a corresponding at least one global positioning system (GPS) satellite.

49. The signal detector of claim 48, wherein the signal of interest generated by the GPS satellite is not tracked continuously.

50. The signal detector of claim 27, wherein the means for receiving receives a parameter of the signal of interest.

51. A method for detecting a signal of interest comprising the steps of:

receiving at least one signal of interest perturbed by noise;

receiving at least one reference signal;

deriving data from a segment of the at least one signal of interest;

multiplying the data with data representative of at least one hypothesis;

providing product data representative of the segment and the at least one hypothesis;

integrating the product data over a duration of time; and

deriving correlation data useful for detecting the signal of interest.

52. The method of claim 51, wherein the signal of interest is a plurality of successive frames separated by a frame boundary, and wherein each the segment having an ending portion of a first frame of the plurality of frames, a beginning portion of a second frame successive to the first frame, and the frame boundary between the first frame and the second frame.

53. The method of claim 52, wherein the at least one reference signal determines the location of the frame boundary.

54. The method of claim 52, wherein the at least one reference signal provides bit synchronization information associated with the signal of interest.

55. The method of claim 52, wherein the at least one reference signal provides information specifying the location of data epochs associated with the signal of interest.

56. The method of claim 55, wherein the at least one reference signal provides information determining phase reversals of the data epochs.

57. The method of claim 52, wherein a phase of the beginning portion of the second frame is in a phase reversal at the frame boundary with respect to the ending portion of the second frame.

58. The method of claim 57, further comprising a step of detecting the phase reversal, wherein the step of integrating is responsive to the step of detecting the phase reversal, and wherein the step of integrating adjusts the beginning portion of the second frame to allow coherent integration to proceed across the frame boundary.

59. The method of claim 57, further comprising a step of detecting the phase reversal, wherein the step of integrating is responsive to the step of detecting the phase reversal, and wherein the step of integrating flips the sign of the data residing in the beginning portion of the second frame to allow coherent integration to proceed across the frame boundary.

60. The method of claim 57, further comprising a step of detecting the frame boundary, wherein the step of integrating is responsive to the step of detecting the frame boundary, and wherein the step of integrating integrates the ending portion of the first frame and the beginning portion of the second frame.

61. The method of claim 57, further comprising a step of detecting the frame boundary, wherein the step of integrating is responsive to the step of detecting a frame boundary, and wherein the step of integrating derives first correlation data by coherently integrating the product data across the frame boundary under a first hypothesis, and derives second correlation data by coherently integrating the product data across the frame boundary under a second hypothesis.

62. The method of claim 61, further comprising a step of selecting one of the first correlation data and the second correlation data based on which of the first hypotheses and the second hypothesis is more likely.

63. The method of claim 62, wherein the first hypothesis assumes the phase of the beginning portion of the second frame is unchanged from the phase of the ending portion of the first frame across the frame boundary, and the second hypothesis assumes the phase of the beginning portion of the second frame flips the sign of the phase across the frame boundary with respect to the phase of the ending portion of the first frame.

64. The method of claim 51, wherein the signal of interest is a carrier signal modulated with a repeating pseudo-noise (PN) code.

65. The method of claim 51, wherein the noise is pseudo-noise.

66. The method of claim 51, wherein the segment has complex data having a real component and an imaginary component, wherein the complex data is processed by the step of multiplying, and wherein the step of integrating integrates through complex addition and complex multiplication so that the correlation data is complex.

67. The method of claim 51, wherein the segment has complex data having a magnitude component and a phase component, wherein the complex data is processed by the step of multiplying, and wherein the step of integrating integrates through complex addition and complex multiplication so that the correlation data is complex.

68. The method of claim 51, further comprising a step of hypothesis generation for generating the at least one hypotheses.

69. The method of claim 51, wherein the reference signal is generated by a cellular network.

70. The method of claim 51, wherein the reference signal is generated by a PCS phone network.

71. The method of claim 51, wherein the step of receiving receives global positioning system (GPS) signals.

72. The method of claim 51, wherein the at least one signal of interest is generated by a corresponding at least one global positioning system (GPS) satellite.

73. The method of claim 72, wherein the signal of interest generated by the GPS satellite is not tracked continuously.

74. The method of claim 51, wherein the step of receiving at least one signal of interest receives a parameter of the signal of interest.

75. A computer readable medium having a program for storing a series of instructions for detecting a signal of interest, the program performing at least the following:

receiving at least one signal of interest perturbed by noise;

receiving at least one reference signal;

deriving data from a segment of the at least one signal of interest;

multiplying the data with data representative of at least one hypothesis;

providing product data representative of the segment and the at least one hypothesis;

integrating the product data over a duration of time; and

deriving correlation data useful for detecting the signal of interest.

76. The computer readable medium of claim 75, wherein the signal of interest is a plurality of successive frames separated by a frame boundary, and wherein each the segment having an ending portion of a first frame of the plurality of frames, a beginning portion of a second frame successive to the first frame, and the frame boundary between the first frame and the second frame.

77. The computer readable medium of claim 76, wherein a phase of the beginning portion of the second frame is in a phase reversal at the frame boundary with respect to the ending portion of the second frame, further having a series of instructions for detecting the phase reversal, wherein the series of instructions for integrating is responsive to the series of instructions for detecting the phase reversal, and wherein the series of instructions for integrating adjusts the beginning portion of the second frame to allow coherent integration to proceed across the frame boundary.

78. The computer readable medium of claim 76, wherein a phase of the beginning portion of the second frame is in a phase reversal at the frame boundary with respect to the ending portion of the second frame, further having a series of instructions for detecting the phase reversal, wherein the series of instructions for integrating is responsive to the series of instructions for detecting the phase reversal, and wherein the series of instructions for integrating flips the sign of the data residing in the beginning portion of the second frame to allow coherent integration to proceed across the frame boundary.

79. The computer readable medium of claim 76, wherein a phase of the beginning portion of the second frame is in a phase reversal at the frame boundary with respect to the ending portion of the second frame, further having a series of instructions for detecting the frame boundary, wherein the series of instructions for integrating is responsive the series of instructions for detecting the frame boundary, and wherein the series of instructions for integrating integrates the ending portion of the first frame and the beginning portion of the second frame.

80. The computer readable medium of claim 76, wherein a phase of the beginning portion of the second frame is in a phase reversal at the frame boundary with respect to the ending portion of the second frame, further having a series of instructions for detecting the frame boundary, wherein the series of instructions for integrating is responsive to the series of instructions for detecting a frame boundary, and wherein the series of instructions for integrating derives first correlation data by coherently integrating the product data across the frame boundary under a first hypothesis, and derives second correlation data by coherently integrating the product data across the frame boundary under a second hypothesis.

81. The computer readable medium of claim 80, wherein the first hypothesis assumes the phase of the beginning portion of the second frame is unchanged from the phase of the ending portion of the first frame across the frame boundary, and the second hypothesis assumes the phase of the beginning portion of the second frame flips the sign of the phase across the frame boundary with respect to the phase of the ending portion of the first frame, and further having a series of instructions for selecting one of the first correlation data and the second correlation data based on which of the first hypotheses and the second hypothesis is more likely.

82. The computer readable medium of claim 75, wherein the segment has complex data having a real component and an imaginary component, wherein the complex data is processed by the series of instructions for multiplying, and wherein the series of instructions for integrating integrates through complex addition and complex multiplication so that the correlation data is complex.

83. The computer readable medium of claim 75, wherein the segment has complex data having a magnitude component and a phase component, wherein the complex data is processed by the series of instructions for multiplying, and wherein the series of instructions for integrating integrates through complex addition and complex multiplication so that the correlation data is complex.

84. The computer readable medium of claim 75, further having a series of instructions for hypothesis generation for generating the at least one hypotheses.

85. The computer readable medium of claim 75, wherein the series of instructions for receiving at least one signal of interest receives a parameter of the signal of interest.