Auxiliary noise power scheduling for on-line secondary path modeling in single channel feedforward active noise control systems

Auxiliary noise, injected in active noise control (ANC) system for on-line secondary path modeling (SPM), contributes to the residual error (which we want to minimize). In this paper, two new schemes for controlling the auxiliary noise injection are proposed. The first method is ON/OFF control in which an additional fixed filter is used to temporarily hold the tap-weights of the adaptive on-line SPM filter. The decision (ON/OFF) is carried out on the basis of difference of power of errors from the two filters. After suspension of the auxiliary noise injection, the algorithm continuously checks for error outliers so that injection may be restarted in the case of path perturbation. In the second method a new auxiliary-noise-power scheduling strategy based on the error signal of the SPM filter is proposed. In both proposed schemes a fixed step-size is used for the SPM filter and the noise control filter, which reduces the computational complexity of the algorithms. In addition to this, in the second method, no off-line modeling (initial phase) of the secondary path is required.