Low-Cost Acoustic Cameras for Underwater Wideband Passive Imaging

Trucco, A.; Martelli, Samuele; Crocco, Marco

doi:10.1109/joe.2014.2377454

Cited by 11 publications

(8 citation statements)

References 25 publications

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“…They include irregular, nonuniform array designs that remove the periodic pattern in array structure and hence in the output of the beamformer for both transmit and receive linear or planar arrays [22,[36][37][38][39][40][41][42]. Another approach for suppressing grating lobes uses nonsinusoidal transmit signals that also remove the periodic pattern in the beamformer output [43].…”

Section: Introductionmentioning

confidence: 99%

“…Grating lobe suppression can also be accomplished via adaptive beamforming that applies a weighting factor either to the echoes received on each sensor element [44,45] or to the transmit aperture [46,47]. Previous work in optimizing array design or performance in ocean acoustic remote sensing applications are based on numerical simulation for a given signal with deterministic frequency or bandwidth [36][37][38][39][40][41][42].…”

Section: Introductionmentioning

confidence: 99%

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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%

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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“…As acoustic waves can penetrate an opaque medium and be able to image the interior of structures, acoustic imaging is one of the best approaches to obtain the interior characteristics of objects. It is used as an important detection tool for medical diagnosis, [1][2][3][4] nondestructive testing, [5][6][7][8][9] sonar, [10][11][12][13][14] and so on. Conventional acoustic imaging is characterized by two features.…”

Section: Introductionmentioning

confidence: 99%

Frequency Representation: Visualization and Clustering of Acoustic Data Using Self-Organizing Maps

Guo

Sun

et al. 2017

Ultrason Imaging

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Extraction and display of frequency information in three-dimensional (3D) acoustic data are important steps to analyze object characteristics, because the characteristics, such as profiles, sizes, surface structures, and material properties, may show frequency dependence. In this study, frequency representation (FR) based on phase information in multispectral acoustic imaging (MSAI) is proposed to overcome the limit of intensity or amplitude information in image display. Experiments are performed on 3D acoustic data collected from a rigid surface engraved with five different letters. The results show that the proposed FR technique can not only identify the depth of the five letters by the colors representing frequency characteristics but also demonstrate the 3D image of the five letters, providing more detailed characteristics that are unavailable by conventional acoustic imaging.

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“…They include irregular, nonuniform array designs that remove the periodic pattern in array structure and hence in the output of the beamformer for both transmit and receive linear or planar arrays [71,[168][169][170][171][172][173][174]. Another approach for suppressing grating lobes uses nonsinusoidal transmit signals that also remove the periodic pattern in the beamformer output [175].…”

Section: Discussionmentioning

confidence: 99%

“…Previous work in optimizing array design or performance in ocean acoustic remote sensing applications are based on numerical simulation for a given signal with deterministic frequency or bandwidth [168][169][170][171][172][173][174].…”

Section: Discussionmentioning

confidence: 99%

Continental-shelf scale Passive Ocean Acoustic Waveguide Remote Sensing of marine mammals and other submerged objects including detection, localization, and classification

Wang¹

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In this thesis, we develop the basics of the Passive Ocean Acoustic Waveguide Remote Sensing (POAWRS) technique for the instantaneous continental-shelf scale detection, localization and species classification of marine mammal vocalizations. POAWRS uses a large-aperture, densely sampled coherent hydrophone array system with orders of magnitude higher array gain to enhance signal-to-noise ratios (SNR) by coherent beamforming, enabling detection of underwater acoustic signals either two orders of magnitude more distant in range or lower in SNR than a single hy-

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Low-Cost Acoustic Cameras for Underwater Wideband Passive Imaging

Cited by 11 publications

References 25 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

Frequency Representation: Visualization and Clustering of Acoustic Data Using Self-Organizing Maps

Continental-shelf scale Passive Ocean Acoustic Waveguide Remote Sensing of marine mammals and other submerged objects including detection, localization, and classification

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