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MIMO-Rekursivfilter für Kugelarrays

Authors Lösler, S.
Year 2014
Thesis Type Master's thesis
Topic Audio Signal Processing
Keywords MIMO filter design, spherical arrays, spherical Hankel and Bessel functions, higher-order Ambisonic microphone arrays, compact spherical loudspeaker arrays
Abstract This work deals with the design of efficient, recursive MIMO-filters, for the equalization and radial steering of multichannel spherical arrays. Such MIMO-systems are basically a filter matrix. FFT already provides an easy method to equalize control systems, which include a filter matrix. But the FFT approach delivers a slight resolution at low frequencies and has also a temporal shift. The goal of this work is to find an efficient implementation with parallel filters. These filters are using a simple parallel IIR filter structure. Their frequency resolution can easily be adjusted and the computational power is always in fixed boundaries. Furthermore, this work deals with recursive filters for radial steering in the Ambisonics-domain. These radial steering filters need to be limited in their dynamics with high-pass filters. This is necessary due to the high amplification of these filters at low frequencies. Additionally the frequency response is adjusted to different types of soundfields and the side lobes are suppressed by a separated weighting of the filter bands.
Supervisors Zotter, F.