Recently the Remote Microphone Technique (RMT) has been implemented in aircrafts to reduce turbofan noise radiation as well as interior noise at some locations where no error sensors can be put; this RMT consists in filtering the signals from real error microphones to estimate the noise at virtual error microphones. Unfortunately, practical implementation of the RMT requires much more real-time computations than the usual X-LMS control algorithm; therefore in the multichannel case the RMT was applied to stationary pure-tone noises only. In this paper, an algorithm is introduced to achieve multichannel broadband control of noise at virtual sensor locations. As for the RMT, this algorithm includes the linear filtering of real error signals but the filters are designed in such a way that the required amount of real-time computations is largely reduced. Secondary path equalization is also used to combine an estimation of the secondary path (from the noise sources to the virtual sensors) with the real error sensor filters into a single matrix of finite impulse responses. Eventually, the algorithm requires roughly the same amount of real-time computations as the multichannel X-LMS algorithm. This Simplified Remote Microphone Technique (SRMT) was implemented in the LMA control hardware system COMPARS. Application of the SRMT to multichannel noise control in a large cavity is briefly discussed in the paper.
A simplified remote microphone technique for active noise control at virtual error sensors
Ein vereinfachtes Fernmikrophonverfahren für die aktive Schallregelung an virtuellen Fehlersensoren
2001
4 Seiten, 2 Bilder, 3 Quellen
Conference paper
English
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