Orthogonal Methods for Filtered-X Algorithms Applied to Active Noise Control Using the Discrete Cosine Transform

A scheme for Active Noise Control (ANC) based on modification of the filtered-x least mean squares (FxLMS) and filtered-x recursive least squares (FxRLS) algorithms are presented in this paper. The proposed system allows saving more computational effort than conventional structures. This is a direct consequence of using an orthogonal transform for decomposing the filter input into a number of finite and mutually exclusive bands. The most important advantage of this approach is that it admits schemes in which each subband is independent form processed allowing an efficient implementation of adaptation mechanisms that in their conventional form would be highly complex. In this case the discrete cosine transform is used to split the input signal into a set of approximately orthogonal signal components with the purpose of increasing performance of the proposed system.