Deconvolution of azimuthal mode detection measurements

Unequally spaced transducer rings make it possible to extend the range of detectable azimuthal modes. The disadvantage is that the response of the mode detection algorithm to a single mode is distributed over all detectable modes, similarly to the Point Spread Function of Conventional Beamforming wi...

Full description

Saved in:
Bibliographic Details
Published in:Journal of sound and vibration 2018-05, Vol.422, p.1-14
Main Authors: Sijtsma, Pieter, Brouwer, Harry
Format: Article
Language:English
Subjects:
Acoustic beamforming
Acoustics
Algorithms
Azimuthal mode detection
Beamforming
Broadband
Deconvolution
Dynamic range
Noise
Non-equally spaced array
Point spread functions
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Unequally spaced transducer rings make it possible to extend the range of detectable azimuthal modes. The disadvantage is that the response of the mode detection algorithm to a single mode is distributed over all detectable modes, similarly to the Point Spread Function of Conventional Beamforming with microphone arrays. With multiple modes the response patterns interfere, leading to a relatively high “noise floor” of spurious modes in the detected mode spectrum, in other words, to a low dynamic range. In this paper a deconvolution strategy is proposed for increasing this dynamic range. It starts with separating the measured sound into shaft tones and broadband noise. For broadband noise modes, a standard Non-Negative Least Squares solver appeared to be a perfect deconvolution tool. For shaft tones a Matching Pursuit approach is proposed, taking advantage of the sparsity of dominant modes. The deconvolution methods were applied to mode detection measurements in a fan rig. An increase in dynamic range of typically 10–15 dB was found.
ISSN:0022-460X
1095-8568
DOI:10.1016/j.jsv.2018.02.029