Imaging of passive targets in shallow-water using an ambient noise acoustic imaging system.

Olivieri, Marc P.; Glegg, Stewart; Coulson, Robert

doi:10.1121/1.415462

Cited by 4 publications

(3 citation statements)

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“…An ambient noise imaging (ANI) camera called ADONIS was built at the Scripps Institute of Oceanography and tested successfully near San Diego in 1995 [3], [4]. The results obtained from field deployments of ADONIS formed images of static underwater objects at range of about 40 m, thus demonstrating that ANI was indeed feasible.…”

Section: Introductionmentioning

confidence: 99%

Ambient Noise Imaging through joint source localization

Kuselan

Pallayil

2011

Oceans'11 MTS/Ieee Kona

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Abstract-Underwater Ambient Noise Imaging (ANI) systems rely on the acoustic illumination produced by natural noise sources to image an object of interest. Snapping shrimp are a dominant natural source of illumination in tropical waters and their snaps occur randomly. Hence incoherent energy detection methods, which require no knowledge of the source locations, are usually employed to form images of the objects. This approach, although simple, only produces images when the anisotropy in ambient noise is conducive. Even in anisotropic noise, some sources 'illuminate' the target while others obscure it. In this paper we describe a different approach. We use a snap detection algorithm to estimate the locations of the noise sources on the sea-bottom and then use the sound from these sources to passively range and form images of the objects. By using only the noise from sources that provide us good illumination and rejecting undesirable sources, we improve the image quality. The feasibility of this approach has been experimentally demonstrated with the data collected during a recent deployment of ROMANIS, an ANI camera developed in Singapore.

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Section: Introductionmentioning

confidence: 99%

Ambient Noise Imaging through joint source localization

Kuselan

Pallayil

2011

Oceans'11 MTS/Ieee Kona

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“…A typical plot is shown in figure 4. In this plot the light green sensors are good sensors, red ones are nonworking, blue ones are out of sync and the dark green sensors are marked faulty manually 3 . The power spectrum corresponding to the signal received by the good sensors were computed and it was found to follow the shape as shown in figure 5.…”

Section: ) Data From First Deploymentmentioning

confidence: 99%

“…The subject of underwater ambient noise imaging has been studied by several researchers [1][2][3][4]. To date there are three systems known to us that have been built for ambient noise imaging applications, namely the Acoustic Daylight Ocean Noise Imaging (ADONIS) system built by Scripps Institute of Oceanography (SIO) California [5], an ambient noise imaging array built by DSTO Australia [6] and ROMANIS built at ARL [7].…”

Section: Introductionmentioning

confidence: 99%

Ambient Noise Imaging-first deployments of ROMANIS and preliminary data analysis

Venugopalan

Tan

Potter

et al. 2003

Oceans 2003. Celebrating the Past ... Teaming Toward the Future (IEEE Cat. No.03CH37492)

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-The Acoustic Research Laboratory (ARL) at the Tropical Marine Science Institute under the National University of Singapore has developed a second generation Ambient Noise Imaging (ANI) system: the Remotely Operated Mobile Ambient Noise Imaging System (ROMANIS). ROMANIS has been primarily developed to study the potential of ANI applications where snapping shrimp are the major natural insonifiers of the environment, as in warm shallow waters like those surrounding Singapore. ROMANIS is a fully digital broadband data acquisition and recording system with over 500 sensors that fully populate a circular aperture of 1.4m. The first at sea deployment was conducted during February 2003 to check the functionality of the system in a real seawater environment (that differs considerably in terms of electronic and acoustic noise from previous tests in tank) and to study the high frequency ambient noise characteristics at the deployment location. It was also required to validate the beamforming algorithms developed for imaging. A GUI-based application helps the user to control the acquisition process and acquire the data synchronously. Approximately 750 Mbytes of data was recorded. A custom software package has been developed which enables reading, processing and the displaying of images from the recorded data. In this paper we present the deployment details and preliminary analysis of the data. The analysis confirms that the energy distribution from snapping shrimp clicks follow a lognormal distribution as previously reported. The validity of the beamforming software has been verified with a 40 kHz pinging source placed some 50 m away from ROMANIS and forming an image of it from the data recorded. A second deployment of the system has been made during MayJune 2003 with targets placed at ranges exceeding any attempted to date and to produce their acoustic images. The data from these recordings are under analysis and some part of it is presented in this paper.

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Development of a Second-Generation Underwater Acoustic Ambient Noise Imaging Camera

Pallayil

Kuselan

Raichur

et al. 2016

IEEE J. Oceanic Eng.

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A nominally circular 2-D broadband acoustic array of 1.3-m diameter, comprising 508 sensors and associated electronics, was designed, built, and tested for ambient noise imaging (ANI) potential in Singapore waters. The system, named Remotely Operated Mobile Ambient Noise Imaging System (ROMANIS), operates over 25-85 kHz, streaming real-time data at 1.6 Gb/s over a fiber optic link. By using sensors that are much larger than halfwavelength at the highest frequency of interest, so with some directionality, good beamforming performance is obtained with a small number of sensors compared to a conventional half-wavelength-spaced array. A data acquisition system consisting of eight single-board computers enables synchronous data collection from all 508 sensors. A dry-coupled neoprene cover is used to encapsulate the ceramic elements as an alternative to potting or oil filling, for easier maintenance. Beamforming is performed in real-time using parallel computing on a graphics processing unit (GPU). Experiments conducted in Singapore waters yielded images of underwater objects at much larger ranges and with better resolution than any previous ANI system. Although ROMANIS was designed for ANI, the array may be valuable in many other applications requiring a broadband underwater acoustic receiving array.Index Terms-Ambient noise imaging (ANI), broadband array design, underwater acoustics, data acquisition.

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Imaging of passive targets in shallow-water using an ambient noise acoustic imaging system.

Cited by 4 publications

References 0 publications

Ambient Noise Imaging through joint source localization

Ambient Noise Imaging through joint source localization

Ambient Noise Imaging-first deployments of ROMANIS and preliminary data analysis

Development of a Second-Generation Underwater Acoustic Ambient Noise Imaging Camera

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