TY - JOUR
T1 - Deconvolution of azimuthal mode detection measurements
AU - Sijtsma, Pieter
AU - Brouwer, Harry
PY - 2018/5/26
Y1 - 2018/5/26
N2 - 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.
AB - 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.
KW - Acoustic beamforming
KW - Azimuthal mode detection
KW - Deconvolution
KW - Non-equally spaced array
UR - http://www.scopus.com/inward/record.url?scp=85044278081&partnerID=8YFLogxK
UR - http://resolver.tudelft.nl/uuid:ce77a3b5-11dc-47d9-a116-4c058d9a5b45
U2 - 10.1016/j.jsv.2018.02.029
DO - 10.1016/j.jsv.2018.02.029
M3 - Article
AN - SCOPUS:85044278081
SN - 0022-460X
VL - 422
SP - 1
EP - 14
JO - Journal of Sound and Vibration
JF - Journal of Sound and Vibration
ER -