On optimal shading for arrays of irregularly-spaced or noncoplanar elements

Gallaudet, Timothy C.; Moustier, Christian P. de

doi:10.1109/48.895363

Cited by 10 publications

(5 citation statements)

References 64 publications

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“…For most array shapes of interest, the geometry is simply curved, so that , and extensions to more terms in the series are not necessary. Using this approximation, the integral form for in (8) is reduced to (11) Based on this expression for , the interpolation polynomial form shown in (5) is in a form that is only dependent on the array shape function and its derivatives evaluated at the element locations, as well as the inter-element array spacing.…”

Section: Methodsmentioning

confidence: 99%

“…The numerical optimization approaches applied to array-shading problems include linear programming techniques [1]- [3], nonlinear programming techniques [4], genetic algorithms [5], simulated annealing [6], and importance sampling [7]. In the area of beampattern matching techniques include simple recursion [8], iterative least-squares [9] and adaptive mainlobe shaping under sidelobe constraints Manuscript [10], [11]. The technique of this paper broadly falls into the category of beampattern matching; however, it uses analytical expressions as opposed to numerical procedures.…”

Section: Introductionmentioning

confidence: 99%

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Element Directivity Compensation for Beamforming a Curved Array

Wettergren

2004

IEEE Signal Process. Lett.

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Conventional delay-and-sum beamforming employs element shading weights that are derived from linear aperture approximations. For many conformal arrays, the aperture of interest is not well approximated by the linear assumption. In this letter, an analytical method for approximating desired linear array beampattern characteristics on a conformal array is presented. The advantage of the method is that array designers can apply rules of thumb learned from linear arrays to conformal arrays without significant degradation in performance. Many of the limitations of using conventional beamforming on conformal array surfaces can be removed by applying the method.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Element Directivity Compensation for Beamforming a Curved Array

Wettergren

2004

IEEE Signal Process. Lett.

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“…Fixed beamformers have a fixed spatial directivity (not dependent on the acoustical environment), and focus on a desired sound source, thereby reducing the influence of background noise, more precisely to attenuate signals outside the line of sight. Examples of fixed beamforming are delay-and-sum beamforming [15,35], weighted-sum beamforming [24], superdirective beamforming [36], and frequency-invariant beamforming [72]. In the case of adaptive beamforming, directivity is dependent on the acoustical environment.…”

Section: Directional Microphones and Beamformersmentioning

confidence: 99%

Superhuman Hearing - Virtual Prototyping of Artificial Hearing: a Case Study on Interactions and Acoustic Beamforming

Geronazzo

Vieira²,

Nilsson

et al. 2020

IEEE Trans. Visual. Comput. Graphics

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“…44,47 This is likely to occur for volume backscatter received by a moving platform and dominated by boundary sidelobe returns, because each sidelobe is directed towards a different grazing angle with respect to the boundary ͑see Ref. 41 for the receive beam patterns of the TVSS͒. The total reverberation will be the sum of the components arriving in each sidelobe, where each component follows a different parent distribution.…”

Section: Scattering Processes Approximated By Log-normal Distributmentioning

confidence: 99%

High-frequency volume and boundary acoustic backscatter fluctuations in shallow water

Gallaudet

Moustier

2003

The Journal of the Acoustical Society of America

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Volume and boundary acoustic backscatter envelope fluctuations are characterized from data collected by the Toroidal Volume Search Sonar (TVSS), a 68 kHz cylindrical array capable of 360 degrees multibeam imaging in the vertical plane perpendicular to its axis. The data are processed to form acoustic backscatter images of the seafloor, sea surface, and horizontal and vertical planes in the volume, which are used to attribute nonhomogeneous spatial distributions of zooplankton, fish, bubbles and bubble clouds, and multiple boundary interactions to the observed backscatter amplitude statistics. Three component Rayleigh mixture probability distribution functions (PDFs) provided the best fit to the empirical distribution functions of seafloor acoustic backscatter. Sea surface and near-surface volume acoustic backscatter PDFs are better described by Rayleigh mixture or log-normal distributions, with the high density portion of the distributions arising from boundary reverberation, and the tails arising from nonhomogeneously distributed scatterers such as bubbles, fish, and zooplankton. PDF fits to the volume and near-surface acoustic backscatter data are poor compared to PDF fits to the boundary backscatter, suggesting that these data may be better described by mixture distributions with component densities from different parametric families. For active sonar target detection, the results demonstrate that threshold detectors which assume Rayleigh distributed envelope fluctuations will experience significantly higher false alarm rates in shallow water environments which are influenced by near-surface microbubbles, aggregations of zooplankton and fish, and boundary reverberation.

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On optimal shading for arrays of irregularly-spaced or noncoplanar elements

Cited by 10 publications

References 64 publications

Element Directivity Compensation for Beamforming a Curved Array

Element Directivity Compensation for Beamforming a Curved Array

Superhuman Hearing - Virtual Prototyping of Artificial Hearing: a Case Study on Interactions and Acoustic Beamforming

High-frequency volume and boundary acoustic backscatter fluctuations in shallow water

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