Modal Mapping Experiment and Geoacoustic Inversion Using Sonobuoys

Frisk, George V.; Becker, Kyle M.; Rajan, Subramaniam D.; Sellers, Cynthia J.; Heydt, Keith von der; Smith, Chad M.; Ballard, Megan S.

doi:10.1109/joe.2014.2362838

Cited by 17 publications

(14 citation statements)

References 21 publications

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“…1. An alternative to using a horizontal array is to create a horizontal synthetic aperture using a drifting source/receiver geometry and accurate navigation as in [22]. The pressure field does not have to be measured for a large range, because the continuous spectrum employed here decays at a rate of r −3/2 (see [24]).…”

Section: Proposed Experiments Based On the Inverse Algorithmmentioning

confidence: 99%

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A Direct Method for the Estimation of Sediment Sound Speed With a Horizontal Array in Shallow Water

Lin

Michalopoulou

2016

IEEE J. Oceanic Eng.

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In this paper, a fast approach for estimating sediment sound speed in a shallow-water environment is developed. Under certain assumptions, this algorithm recovers the seabed sound-speed profile using pressure field measurements at low frequencies. The geometry of the problem involves measuring the pressure at horizontally placed hydrophones in the water column. The Deift-Trubowitz integral equation is then solved. This work introduces two methods for this task. The first is a modified Born approximation that builds upon a standard first-order approximation; the second is based on interpolating the integrand. It is shown with synthetic data that these methods work well with successful sound-speed estimation and identification of sharp discontinuities in sound speed. Although the methods are stable and effective with noise-free data, problems arise when noise contaminates the acoustic field. Regularization approaches, reducing the disruptive effect of singular points and smoothing a measured reflection coefficient, are developed to remedy this problem, leading to improved results in noisy environments. In addition to providing soundspeed estimates, the method also computes sediment thickness. This feature is of particular interest, since it makes the method suitable as a preprocessing step providing useful information to other inversion methods. Sensitivity analyses demonstrate that some assumptions required for the approach implementation are not restrictive.Index Terms-Direct methods, geoacoustic inversion, sediment sound speed.

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Section: Proposed Experiments Based On the Inverse Algorithmmentioning

confidence: 99%

“…A different family of methods is local optimization based [17]- [22]. A linearization approach is first implemented to simplify the highly nonlinear model relating geoacoustic parameters to acoustic data, followed by the iterative solution of a quasi-linear system using simple methods such as least squares and regularization.…”

Section: Introductionmentioning

confidence: 99%

A Direct Method for the Estimation of Sediment Sound Speed With a Horizontal Array in Shallow Water

Lin

Michalopoulou

2016

IEEE J. Oceanic Eng.

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“…These signals were acquired by freely drifting buoys. The details of the experiment are explained in [1]. During the narrow band experiment, the ship's tracks and the location of the buoys were in the general area covered by transmissions from Waypoints 3 and 4.…”

Section: Comparison With Other Geo-acoustic Models Determined During mentioning

confidence: 99%

“…In some areas, the 'R' reflector is covered only by the layered unit. A more complete description of the sediment structure is in [1]. The New Jersey shelf area where MOMAXV was conducted has been the site of several other acoustic experiments.…”

Section: Comparison With Other Bottom Modelsmentioning

confidence: 99%

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Estimation of Sediment Properties Using Air Launched Sonobuoys

Rajan¹

2014

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The US Navy has been developing its Multi-Static Active Coherent (MAC) acoustic search system. MAC is an air launched acoustic search system that combines a newly developed coherent source sonobuoy with a field of receiver sonobuoys. With the introduction of the coherent source, operational search data collected during MAC exercises are well suited for post-processing to infer waveguide properties. The long term goal of this research is to investigate the feasibility of estimating sedient acoustic properties using data collected during such exercises. OBJECTIVES Modal dispersion data are used in inversion schemes that estimate sediment properties in range independent and range-dependent environments. The experimental scenario for the use of air launched sonobuoys to extract information about the sediment properties in the area covered by the sonobuoys is to have one of the sonobuoys broadcast a broad band signal with a large set of buoys receive these signals. These receiving sonobuoys will be dispersed over a wide area. In such an experimental set up the data acquired by the sonobuoys is used to estimate the sediment properties in the area covered by the sonobuoys. In March 2011, an experiment termed MOMAXV was conducted off the New Jersey coast. In this experiment broad band signals were broadcast from a ship carrying the source. The ship moved to discrete locations around a small set of free-floating buoys. This mimicked the situation where we have a near stationary sonobuoy with a source transmitting a broadband signals and a network of freely floating sonobuoys acquiring the transmitted signals. The objective of the current work is to analyze the data collected during the experiment and estimate the sediment properties of the region between the ship positions and the location of the sonobuoys. APPROACH A. Experiment details MOMAXV was conducted between March 5 and March 18, 2011 off the coast of New Jersey. The complete details of the experiment are described in Frisk et al [1] which is devoted to analysis of narrow band data collected during the experiment. The experiment also included a broad band Report Documentation Page Form Approved OMB No. 0704-0188 Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number.

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Reconstruction of Dispersion Curves in the Frequency-Wavenumber Domain Using Compressed Sensing on a Random Array

Drémeau

Courtois

Bonnel

2017

IEEE J. Oceanic Eng.

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International audienceIn underwater acoustics, shallow-water environments act as modal dispersive waveguides when considering low-frequency sources, and propagation can be described by modal theory. In this context, propagated signals are composed of few modal components, each of them propagating according to its own wavenumber. Frequency-wavenumber (f−k) representations are classical methods allowing modal separation. However, they require large horizontal line sensor arrays aligned with the source. In this paper, to reduce the number of sensors, a sparse model is proposed and combined with prior knowledge on the wavenumber physics. The method resorts to a state-of-the-art Bayesian algorithm exploiting a Bernoulli–Gaussian model. The latter, well suited to the sparse representations, makes possible a natural integration of prior information through a wise choice of the Bernoulli parameters. The performance of the method is quantified on simulated data and finally assessed through a successful application on real data

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Modal Mapping Experiment and Geoacoustic Inversion Using Sonobuoys

Cited by 17 publications

References 21 publications

A Direct Method for the Estimation of Sediment Sound Speed With a Horizontal Array in Shallow Water

A Direct Method for the Estimation of Sediment Sound Speed With a Horizontal Array in Shallow Water

Estimation of Sediment Properties Using Air Launched Sonobuoys

Reconstruction of Dispersion Curves in the Frequency-Wavenumber Domain Using Compressed Sensing on a Random Array

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