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Browsing by Subject "LMS algorithm"

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    Item type:Article, Access status: Open Access ,
    Active noise control with moving error microphone
    (Wydawnictwa AGH, 2008) Michalczyk, Małgorzata
    Electro-acoustic plants controlled by active noise control (ANC) systems in enclosures are usually time-varying. Their changes can be caused by movements of an error microphone, around which zones of quiet are created. Then, the time variations of the electro-acoustic plant can be fast and adaptive ANC algorithms for tracking variations of error microphone position should be used. The preliminary research results showed that the created zone of quiet can move tracking the movement of the error microphone, when filtered-x least mean squares (FX-LMS) algorithm is applied. The paper presents further results of real-world experiments conducted on a special laboratory stand, which enabled to move the error microphone round the circle trajectory with constant rota- tional speed. Two modifications of FX-LMS algorithm were applied in order to accelerate control algorithm convergence and improve tracking properties of the ANC system: normalized FX-LMS and modified FX-LMS algorithm. It was shown, that the zone of quiet can track movement of the error microphone, however, there was no significant difference in control algorithms performance. In all cases the zone of quiet tracked the movement of the error microphone, even for the error microphone velocity as high as 3.7 m/s, and high attenuation was obtained - from 16 dB for the fast microphone movement up to 28 dB for the slowest microphone movement.