Signal processing system and method for calibrating channel signals supplied from an array of sensors having different operating characteristics

• US 8,050,717 B2
• Filed: 09/01/2006
• Issued: 11/01/2011
• Est. Priority Date: 09/02/2005
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Sugiyama, Akihiko
• Primary Examiner(s): Afshar; Kamran
• Assistant Examiner(s): Obayanju; Omoniyi
• Application Number:
  US11/514,204
• Publication Number:
  US 20070053455A1
• Time in Patent Office: 1,887 Days
• Field of Search: 381/92, 381/122, 375/229, 324/130, 706/24, 455/570
• US Class Current: 455/561
• CPC Class Codes: H04B 17/21 for calibration; for correcting measurements
• CPC Class Codes: H04R 1/406 microphones
• CPC Class Codes: H04R 2201/401 2D or 3D arrays of transducers
• CPC Class Codes: H04R 2201/403 Linear arrays of transducers
• CPC Class Codes: H04R 2430/25 Array processing for suppression of unwanted side-lobes in directivity characteristics, e.g. a blocking matrix
• CPC Class Codes: H04R 3/005 for combining the signals of two or more microphones specially adapted for hearing aids H04R25/407

Abstract

In a signal processing system, a set of channel signals from an array of sensors of different operating characteristics are processed in calibration circuitry that calculates individual average values of the channel signals and calculates an average of the individual average values of channel signals as a reference value. Reciprocal calculators calculate reciprocal values of the individual average values of the channel signals. Scaling circuitry scales the reciprocal values by the reference value to produce a set of amplitude calibration signals and scales the channel signals by the calibration signals respectively. As a result, the channel signals are normalized by their own average values and scaled by the reference value to produce a set of calibrated channel signals.

Claims

1. A signal processing system for processing a plurality of channel signals supplied from an array of sensors of different operating characteristics, comprising calibration circuitry that determines a single reference signal common to all channel signals from said channel signals, generates first copies of said channel signals and second copies of said channel signals, and produces calibrated channel signals that are equal to said first copies normalized respectively by average values of said second copies and scaled by said reference signal.

2. The signal processing system of claim 1, wherein, said calibration circuitry comprises:

reference calculation circuitry that calculates individual average values of said channel signals and determines said reference signal from said individual average values;

reciprocal calculation circuitry that calculates reciprocal values of said individual average values; and

scaling circuitry that scales said reciprocal values by said reference signal to produce a plurality of amplitude calibration signals and scales said channel signals by said calibration signals respectively.

3. The signal processing system of claim 2, wherein said reference signal is an average value of said individual average values.

4. The signal processing system of claim 3, wherein said individual average values are individual average power values of said channel signals and said average value of said individual average values is average power of said average power values.

5. The signal processing system of claim 1, further comprising:

phase correction circuitry that calculates average phase angle values of phase information signals of said channel signals, and determines a reference phase angle value from said average phase angle values of channel signals; and

phase shifting circuitry that phase shifts the average phase angle values of said phase information signals with said reference phase angle value to produce a plurality of phase calibration signals and phase shifts said phase information signals of channel signals with said phase calibration signals, respectively.

6. The signal processing system of claim 5, wherein said reference phase value is an average value of said phase angle values of channel signals.

7. The signal processing system of claim 1, further comprising:

phase correction circuitry that determines relative delay time difference values between said channel signals and determines a reference delay time difference value from said relative delay time difference values; and

phase shifting circuitry that phase shifts the relative delay time difference values with said reference delay time difference value to produce a plurality of phase calibration signals and phase shifts phase information signals of said channel signals with said phase calibration signals, respectively.

8. The signal processing system of claim 7, wherein said reference delay time difference value is an average value of said relative delay time difference values.

9. The signal processing system of claim 1, further comprising beamforming circuitry that fou ns a beam on signals arriving on said sensor array in a predetermined direction by using said calibrated channel signals from said calibration circuitry.

10. The signal processing system of claim 9, further comprising null forming circuitry that forms a null on signals arriving on said sensor array in a predetermined direction by using said calibrated channel signals from said calibration circuitry and a canceller that adaptively processes said channel signals by using said beam and said null.

11. The signal processing system of claim 9, wherein said beamforming circuitry adaptively performs the forming of said beam.

12. The signal processing system of claim 10, wherein said null forming circuitry adaptively performs the forming of said null.

13. The signal processing system of claim 10, wherein a combination of said beamforming circuitry, said null forming circuitry and said canceller is a generalized sidelobe canceller.

14. The signal processing system of claim 1, further comprising estimation circuitry for estimating the direction of arrival of signals on said array of sensors by using said calibrated channel signals.

15. A method of processing a plurality of channel signals supplied from an array of sensors of different operating characteristics, comprising the steps of calibrating said channel signals by determining a single reference signal common to all channel signals from said channel signals, generates first copies of the channel signals and second copies of the channel signals, and producing calibrated channel signals that are equal to said first copies normalized respectively by average values of said second copies and scaled by said reference signal.

16. The method of claim 15, wherein said calibrating step comprises the steps of:

a) calculating individual average values of said channel signals and deteimining said reference signal from said individual average values;

b) calculating reciprocal values of said individual average values; and

c) scaling said reciprocal values by said reference signal to produce a plurality of amplitude calibration signals and scaling said channel signals by said calibration signals respectively.

17. The method of claim 16, wherein said reference signal is an average value of said individual average values.

18. The method of claim 16, wherein said individual average values are individual average power values of said channel signals and said average value of said individual average values is average power of said individual average power values.

19. The method of claim 15, further comprising:

calculating average phase angle values of phase information signals of said channel signals;

determining a reference phase angle value from said average phase angle values of channel signals;

phase shifting the average phase angle values of said phase information signals with said reference phase angle value to produce a plurality of phase calibration signals; and

phase shifting said phase information signals of channel signals with said phase calibration signals, respectively.

20. The method of claim 19, wherein said reference phase value is an average value of said phase angle values of channel signals.

21. The method of claim 15, further comprising:

determining relative delay time difference values between said channel signals and determining a reference delay time difference value from said relative delay time difference values;

phase shifting the relative delay time difference values with said reference delay time difference value to produce a plurality of phase calibration signals; and

phase shifting said phase information signals of channel signals with said phase calibration signals, respectively.

22. The method of claim 21, wherein said reference delay time difference value is an average value of said relative delay time difference values of channel signals.

23. The method of claim 15, further comprising the step of forming a beam on signals arriving on said sensor array in a predetermined direction by using the calibrated channel signals.

24. The method of claim 23, further comprising the step of forming a null on signals arriving on said sensor array in a predetermined direction by using the calibrated channel signals and adaptively processing said calibrated channel signals by using said beam and said null.

25. The method of claim 23, wherein the step of forming a beam adaptively performs the forming of said beam.

26. The method of claim 24, wherein said null forming step adaptively performs the forming of said null.

27. The method of claim 24 wherein a combination of said beamforming step, said null forming step and said adaptively processing step is performed by using a generalized sidelobe canceller.

28. The method of claim 15, further comprising estimating the arrival direction of signals on said array of sensors by using said calibrated channel signals.