engleski

Application Possibilities of Adaptive Filters Derived from Orthogonal Functions in Active Noise Control

Acoustic feedback from the secondary sources to the reference signal sensor(s) substantially influences on performance of adaptive active noise control systems, and introduces poles in the overall plant that is to be identified (modeled). Application of adaptive infinite impulse response (IIR) filters allows modeling of the overall transfer functions with poles and zeros, but some adaptive weights updating procedures, otherwise computationally simple to implement, can suffer from the problems with convergence and stability. This paper discusses application possibilities of adaptive discrete-time filters derived from orthogonal functions in active noise control. Specially filters derived from Legendre orthogonal functions are studied. The discussed filters have unimodal performance surface, and even more, they are unconditionally stable. This investigation treats one-dimensional acoustic systems (ducts), as well as global and local control of three-dimensional enclosed sound fields. Single channel, and multiple-channel control is analyzed.

active noise control; adaptive filters; orthogonal functions

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