Multigrid reconstruction of sound fields using moving microphones

Katzberg, Fabrice; Mazur, Radoslaw; Maass, Marco; Koch, Philipp; Mertins, Alfred

doi:10.1109/hscma.2017.7895588

Cited by 4 publications

(2 citation statements)

References 15 publications

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“…Finally, note that this Doppler-domain subband procedure can be regarded as the generalized Fourier equivalent to the specific multigrid recovery scheme described in (Katzberg et al, 2017a;.…”

Section: System Of Linear Equations For Subband Parametersmentioning

confidence: 99%

Doppler frequency analysis for sound-field sampling with moving microphones

Katzberg,

Maass,

Mertins

2024

Front. Signal Process.

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Moving microphones allow for the fast acquisition of sound-field data that encode acoustic impulse responses in time-invariant environments. Corresponding decoding algorithms use the knowledge of instantaneous microphone positions for relating the dynamic samples to a positional context and solving the involved spatio-temporal channel estimation problem subject to the particular parameterization model. Usually, the resulting parameter estimates are supposed to remain widely unaffected by the Doppler effect despite the continuously moving sensor. However, this assumption raises issues from the physical point of view. So far, mathematical investigations into the actual meaning of the Doppler effect for such dynamic sampling procedures have been barely provided. Therefore, in this paper, we propose a new generic concept for the dynamic sampling model, introducing a channel representation that is explicitly based on the instantaneous Doppler shift according to the microphone trajectory. Within this model, it can be clearly seen that exact trajectory tracking implies exact Doppler-shift rendering and, thus, enables unbiased parameter recovery. Further, we investigate the impact of non-perfect trajectory data and the resulting Doppler-shift mismatches. Also, we derive a general analysis scheme that decomposes the microphone signal along with the encoded parameters into particular subbands of Doppler-shifted frequency components. Finally, for periodic excitation, we exactly characterize the Doppler-shift influences in the sampled signal by convolution operations in the frequency domain with trajectory-dependent filters.

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Section: System Of Linear Equations For Subband Parametersmentioning

confidence: 99%

Doppler frequency analysis for sound-field sampling with moving microphones

Katzberg,

Maass,

Mertins

2024

Front. Signal Process.

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“…The authors of [6,7,8] target microphones that are moving rapidly in that the movement is so fast it introduces changes in the captured signal that are similarly fast, like those changes that are due to the time dependency of the source signal. These methods assume trajectories such as Lissajous figures that are difficult to implement in practice.…”

Section: Introductionmentioning

confidence: 99%

Comparison of Position Estimation Methods for the Rotating Equatorial Microphone

Lawrence

Ahrens

Peters

2022

2022 International Workshop on Acoustic Signal Enhancement (IWAENC)

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We present a prototype of a microphone that moves rapidly along the equator of a rigid spherical scatterer. Our prototype allows for up to 100 rotations per second. It will enable processing methods like beamforming or sound field decomposition that are conventionally performed using microphone arrays. Solutions that assume one or more moving microphones have already been proposed in the literature but have not been verified in practise. Most of these methods require precise knowledge of the instantaneous microphone position, for which no convenient practical solution exists. Recent advancements in microphone array processing enable employing simple microphone trajectories, and recent advancements in 3D printing, microcontrollers, and highspeed electric motors allow for the required control of the movement. This paper presents the design of our prototype and evaluates its performance. Of particular interest is the accuracy of the estimation of the microphone's instantaneous position. This paper demonstrates that monitoring the passing time instants of a photodiode that is integrated into the rotating sphere provides the highest precision and robustness.

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