Vuksanovic B., Nikolic D.

This paper discusses some modifications made to a well known FXLMS adaptive filtering algorithm in order to improve its performance, namely rate of convergence, minimum mean squared error and computational load of the implemented algorithm. Presented modification - Filtered-Inverse LMS (FILMS) algorithm uses the inverse of the secondary acoustic path in order to improve system convergence. The secondary acoustic path refers here to the path from controller output to the error microphone in the active noise control system. Mathematical apparatus used to analyse this algorithm is presented in this paper. Some simulations have been performed in order to confirm the accuracy of the performed mathematical analysis. Results of these simulations are presented in the paper showing very good agreement between the developed theory and the algorithm performance. It is also shown that the rate of convergence of this algorithm is superior when compared to a FXLMS algorithm where convergence rate remains highly dependent upon the conditioning of the autocorrelation matrix of input signals. Further in the paper, in addition to the single channel algorithm discussion and analysis, a couple of multichannel FILMS configurations are proposed and their performance evaluated. Some initial laboratory results using single and multichannel FILMS algorithm configurations are presented at the conclusion of the paper.