Method for tuning an adaptive leaky LMS filter
First Claim
1. A method of tuning an adaptive feedforward noise cancellation algorithm, comprising the acts of:
- providing a feedforward LMS tuning algorithm including at least first and second time varying parameters; and
adjusting said at least first and second time varying parameters as a function of instantaneous measured acoustic noise, a weight vector length and measurement noise variance.
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Abstract
A method to automatically and adaptively tune a leaky, normalized least-mean-square (LNLMS) algorithm so as to maximize the stability and noise reduction performance in feedforward adaptive noise cancellation systems. The automatic tuning method provides for time-varying tuning parameters λk and μk that are functions of the instantaneous measured acoustic noise signal, weight vector length, and measurement noise variance. The method addresses situations in which signal-to-noise ratio varies substantially due to nonstationary noise fields, affecting stability, convergence, and steady-state noise cancellation performance of LMS algorithms. The method has been embodied in the particular context of active noise cancellation in communication headsets. However, the method is generic, in that it is applicable to a wide range of systems subject to nonstationary, i.e., time-varying, noise fields, including sonar, radar, echo cancellation, and telephony.
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Citations
5 Claims
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1. A method of tuning an adaptive feedforward noise cancellation algorithm, comprising the acts of:
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providing a feedforward LMS tuning algorithm including at least first and second time varying parameters; and
adjusting said at least first and second time varying parameters as a function of instantaneous measured acoustic noise, a weight vector length and measurement noise variance. - View Dependent Claims (2, 3, 4)
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5. The method of tuning an algorithm for providing noise cancellation, comprising the acts of:
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receiving a measured reference signal, the measured reference signal including a measurement noise component having a measurement noise value of known variance; and
generating an acoustic noise cancellation signal according to the formulas;
yk=WkTXk Wk+1=λ
kWk+μ
kXkekwherein time varying parameters λ
k and μ
k are determined according to the formulas;
wherein Xk+Qk is a measured reference signal;
Qk is electronic noise and quantization;
σ
q2 is a known variance of the measurement noise; and
L is the length of weight vector Wk.
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Specification