Method and system for correcting transducer non-linearities

• US 20070140058A1
• Filed: 11/21/2005
• Published: 06/21/2007
• Est. Priority Date: 11/21/2005
• Status: Abandoned Application

• Current Assignee: Motorola Mobility, Inc. (Lenovo Group Ltd.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: McIntosh, Jason, Yagunov, Mikhail, Pavlov, Peter
• Application Number:
  US11/283,616
• Publication Number:
  US 20070140058A1
• Time in Patent Office: Days
• US Class Current: 367/140
• CPC Class Codes: H04R 3/04 for correcting frequency response

Abstract

The embodiments of the invention concern a method (400) and system (100) for modeling transducer non-linearities. The method can include converting (402) a transducer signal to a displacement signal that is proportional to a transducer cone displacement, and applying (404) a correction to the displacement signal. The transducer signal can be one of an input signal to the transducer (102) or an acoustic output signal of the transducer. The method can account for at least one mechanical transducer non-linearity which can be a cone excursion, a diaphragm stiffness, or a diaphragm displacement. The method can account for at least one acoustic transducer non-linearity which can account for an acoustic jetting out of a port. The system can further include a sensor coupled to said transducer for physically measuring a cone displacement.

Claims

1. A method for modeling transducer non-linearities, comprising

converting a transducer signal to a displacement signal that is proportional to a transducer cone displacement;

and

applying a correction to said displacement signal,

wherein said transducer signal can be one of an input signal to said transducer or an acoustic output signal of said transducer.

2. The method of claim 1, wherein said correction comprises:

accounting for at least one mechanical transducer non-linearity for producing a distorted displacement signal.

3. The method of claim 2, wherein a mechanical transducer non-linearity is at least one of a transducer diaphragm excursion, a diaphragm stiffness, or a diaphragm displacement.

4. The method of claim 3, further comprising:

applying a time derivative operator to said distorted displacement signal for producing a velocity signal; and

apply a second correction to said velocity signal.

5. The method of claim 4, wherein said second correction comprises:

accounting for at least one acoustic transducer non-linearity for producing a distorted velocity signal.

6. The method of claim 5, wherein an acoustic transducer non-linearity includes non-linear acoustic jetting through at least one transducer port.

7. The method of claim 6, further compromising:

applying a whitener to said distorted velocity signal; and

converting said distorted velocity signal into an acceleration signal.

8. The method of claim 7, wherein said acceleration signal is an estimate of the sound pressure level produced by said transducer.

9. The method of claim 1, wherein said applying at least one correction is one of a fixed or adaptive process using a convergence error of an adaptation process during said correction, and at least one correction is a memory-less and nonlinear operation.

10. A method for echo suppression, comprising

converting a transducer signal to a displacement signal which is proportional to a transducer cone displacement;

applying at least one correction to said displacement signal to produce an acceleration signal for suppressing at least one non-linear component of said transducer signal; and

using said acceleration signal as an input to for echo cancellation for suppressing an echo from a microphone input signal,

wherein said acceleration signal facilitates a convergence of the echo cancellation.

11. A system for suppressing transducer non-linearities, comprising

a displacement unit for converting an input signal to a displacement signal that is proportional to a cone displacement of a transducer;

and

at least one non-linear estimator for modeling at least one transducer non-linearity and applying at least one correction to said displacement signal,

wherein at least one non-linear estimator receives said displacement signal from said displacement unit to predict at least one distortion generated by said transducer for producing a distorted signal.

12. The system of claim 11, further comprising:

a transducer for producing an acoustic signal in response to said input signal, said transducer imparting at least one non-linear component onto said acoustic signal. related to at least one transducer non-linearity;

a microphone for converting said acoustic signal into an audio signal, said audio signal including a linear component which is a linear function of said acoustic signal and a non-linear component which is a non-linear function of said transducer; and

an echo suppressor, responsive to said distorted signal, for suppressing said linear component of said audio signal received by said microphone.

13. The system of claim 12, wherein said distorted signal compensates for at least one transducer non-linearity thereby facilitating a convergence of the echo suppressor.

14. The system of claim 11, wherein said non-linear estimator applies a memory-less non-linear distortion to the displacement signal that takes transducer non-linearities into account.

15. The system of claim 11, wherein said non-linear estimator accounts for at least one mechanical transducer non-linearity that is at least one of a transducer cone excursion, a diaphragm stiffness, or a magnetic induction.

16. The system of claim 11, further comprising:

a differential operator for converting said distorted signal into a velocity signal; and

a second non-linear estimator for applying a second distortion to said velocity signal to model at least one acoustic transducer non-linearity for producing a distorted velocity signal.

17. The system of claim 16, wherein an acoustic transducer non-linearity is a non-linear acoustic jetting through at least one transducer port that is proportional to an instantaneous acoustic velocity.

18. The system of claim 12, further comprising:

a spectral whitener for flattening a spectrum of said distorted signal,

wherein the spectral whitener receives said distorted signal from a non-linear estimator and provides a whitened signal to an input of said echo suppressor.

19. The system of claim 12, wherein said first non-linear estimator and said second non-linear estimator receive a convergence error from said echo canceller and adapt using a gradient search algorithm.

20. The system of claim 11, further comprising:

a sensor coupled to said transducer for physically measuring a cone displacement, wherein said displacement unit converts an input signal to a displacement signal using said cone displacement.