ARAP - Deep Ocean Vector Sensor Research Array

McEachern, James F.; McConnell, James A.; Jamieson, John; Trivett, D. H.

doi:10.1109/oceans.2006.307082

Cited by 14 publications

(6 citation statements)

References 3 publications

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“…The ONR-FORA is a linear oil-filled array consisting of four nested subapertures, each uniformly spaced, designed for beamforming signals without spatial aliasing over frequencies spanning from below 250 Hz up to 2000 Hz. The nested configuration of the ONR-FORA follows standard array design typically employed in wide-area ocean acoustic array construction, making the analysis and results presented here for the ONR-FORA applicable to other such nonuniformly-spaced arrays with nested subapertures (examples of other ocean acoustic arrays with nested apertures are provided in [9,10,48,49]). Previously, all data acquired by the ONR-FORA and other coherent ocean acoustic arrays were beamformed using conventional uniformly-spaced single or individual subapertures [1,2,7,8,[11][12][13]24,[48][49][50].…”

Section: Introductionmentioning

confidence: 99%

Angular Resolution Enhancement Provided by Nonuniformly-Spaced Linear Hydrophone Arrays in Ocean Acoustic Waveguide Remote Sensing

Wang

Ratilal

2017

Remote Sensing

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Uniformly-spaced apertures or subapertures of large, densely-sampled, discrete linear receiver arrays are often used in remote sensing to increase the signal-to-noise ratio (SNR) by coherent beamforming that reduces noise coming from directions outside the signal beam. To avoid spatial aliasing or the presence of grating lobes in real spatial directions, the uniformly-spaced array inter-element spacing d sets a limit on the maximum frequency f max < c/2d of signals suitable for beamforming with the array, where c is the medium's wave propagation speed. Here, we show that a nonuniformly-spaced array, for instance, formed by combining multiple uniformly-spaced subapertures of a nested linear array, can significantly enhance the array angular resolution while simultaneously avoiding dominant grating lobes in real angular space, even for signals with frequencies beyond the maximum that the array is designed for. The array gain, beam width, and maximum grating lobe height are quantified for the Office of Naval Research Five Octave Research Array (ONR-FORA) for various combinations of its uniformly-spaced subapertures, leading to nonuniformly-spaced subarrays. Illustrative examples show angular resolution enhancement provided by the nonuniformly-spaced ONR-FORA subarrays over that of its uniformly-spaced individual subaperture counterparts in both active and passive ocean acoustic waveguide remote sensing, drawn from measurements in the Gulf of Maine 2006 Experiment.

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Section: Introductionmentioning

confidence: 99%

Angular Resolution Enhancement Provided by Nonuniformly-Spaced Linear Hydrophone Arrays in Ocean Acoustic Waveguide Remote Sensing

Wang

Ratilal

2017

Remote Sensing

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“…It has been shown experimentally that the AVS is advantageous over the omnidirectional pressure sensor as it presents an increased gain against the ambient noise and a higher angular resolution in virtue of the directional capabilities of particle velocity sensors. [19][20][21][22][23] Superdirectivity can be achieved by using an array of AVS subject to stringent constraints on the aperture. The uniform circular array (UCA) of two-dimensional (2D) AVS 24 is such an example.…”

Section: Introductionmentioning

confidence: 99%

Low-frequency beamforming for a miniaturized aperture three-by-three uniform rectangular array of acoustic vector sensors

Guo

Yang

Miron

2015

The Journal of the Acoustical Society of America

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This paper proposes a mode domain beamforming method for a 3 × 3 uniform rectangular array of two-dimensional (2D) acoustic vector sensors with inter-sensor spacing much smaller than the wavelengths in the working frequency band. The acoustic modes are extracted from the particle velocity observations in light of the source-sink pictures of the Taylor's series multipoles [Wikswo and Swinney, J. Appl. Phys. 56(11), 3039-3049 (1984)]. Then, similar to other mode domain methods, the modes are synthesized to obtain the desired beam pattern. The proposed method is limited to the cases where five is the maximum order of the modes for pattern synthesis, meaning that the directivity index in the 2D isotropic noise case can reach up to 10.4 dB. The proposed method has been validated by field experiments.

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“…Fiber optic sensors are well suited for these applications because they are lightweight and electrically passive. Vector sensors operating at low frequencies (< 1 kHz) are typically large due to the need for a large inertial mass [1,2]. However, fiber laser cantilever sensors are highly sensitive to cantilever deflections, which enable significant miniaturization when a surrounding fluid is used to directly drive the cantilever.…”

Section: Introductionmentioning

confidence: 99%

Miniaturization of acoustic vector sensors enabled by viscous fluids: Towards fiber laser hair sensors

et al. 2013

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Aluminum ribbonBrass rod Figure 1. Cantilever designs (a) 6 mm brass rod, (b) 50 m aluminum ribbon, (c) 20 m-offset-core optical fiber.Abstract-We demonstrate a path towards the miniaturization of fiber-optic acoustic sensors based on simple cantilever designs. The reduction in response due to miniaturization is offset by the introduction of a viscous fluid around the cantilever, which changes the dominant driving force and introduces damping. This dramatically changes the response and enables responses 10 times greater than otherwise expected, as well as increased operating bandwidth. We show the performance of several different cantilever sensors and the effect of different viscous fluids on their acoustic response. Theoretical modeling results show excellent agreement with our measured data.

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ARAP - Deep Ocean Vector Sensor Research Array

Cited by 14 publications

References 3 publications

Angular Resolution Enhancement Provided by Nonuniformly-Spaced Linear Hydrophone Arrays in Ocean Acoustic Waveguide Remote Sensing

Angular Resolution Enhancement Provided by Nonuniformly-Spaced Linear Hydrophone Arrays in Ocean Acoustic Waveguide Remote Sensing

Low-frequency beamforming for a miniaturized aperture three-by-three uniform rectangular array of acoustic vector sensors

Miniaturization of acoustic vector sensors enabled by viscous fluids: Towards fiber laser hair sensors

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