Patent Document ID: 20110235693
Application ID: 13071712
Patent Flag: 0

Claim One:
1. A method of operating a multi-channel active noise cancellation comprising: operating a random noise generator to feed noise to at least two control sources; using at least two transducers to measure responses to the noise; forming an estimated secondary path transfer function matrix (SPTFM) [ŝ] KM based upon the transducer responses; taking a Fast Fourier Transform of the estimated SPTFM [ŝ] KM ; calculating a mean magnitude of a main path of each column of the estimated SPTFM [Ŝ] KM ; dividing each column of the estimated SPTFM [ŝ] KM by its respective main path mean magnitude; multiplying by a reference value to obtain a virtual SPTFM [s e ] KM ; applying a filtered-x least mean squares algorithm with the virtual SPTFM [s e ] KM to update coefficients of an adaptive filter; generating a reference signal correlated with the undesired noises in a working environment; filtering the reference signal using the adaptive filter to produce a cancellation signal; using the cancellation signal to drive the sources to cancel noise associated with the reference signal in the working environment; and recursively adjusting the adaptive filter with the filtered reference signal.