Experimental Testing of the Blind Ocean Acoustic Tomography Concept

Jesus, S. M.; Soares, C.; Onofre, J.; Coelho, Emanuel; Picco, Paola

doi:10.1007/978-94-010-0626-2_54

Cited by 4 publications

(2 citation statements)

References 7 publications

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“…A first attempt using a simple periodogram based spectral estimator for frequency selection was shown in Ref. 31 and a similar estimator coupled with an amplitude estimator for frequency selection and weighting in Ref. 23.…”

Section: Inversion Results With a Coherence-based Frequency Selectionmentioning

confidence: 99%

An experimental demonstration of blind ocean acoustic tomography

Jesus

Soares

Coelho

et al. 2006

The Journal of the Acoustical Society of America

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Despite the advantages clearly demonstrated by ocean acoustic tomography ͑OAT͒ when compared to other ocean monitoring techniques, it suffers from several technical-related drawbacks. One is the requirement for rather expensive equipment to be maintained and operated at several locations in order to obtain sufficient source-receiver propagation paths to cover a given ocean volume. This paper presents the preliminary feasibility tests of a concept that uses ships of opportunity as sound sources for OAT. The approach adopted in this paper views the tomographic problem as a global inversion that includes determining both the emitted signal and the environmental parameters, which is a similar problem to that seen in blind channel identification and was therefore termed blind ocean acoustic tomography ͑BOAT͒. BOAT was tested on a data set acquired in October 2000 in a shallow-water area off the west coast of Portugal, including both active and passive ͑ship noise͒ data. Successful results show that BOAT is able to estimate detailed water column temperature profiles coherent with independent measurements in intervals where the uncontrolled source signal ͑ship noise͒ presents a sufficient bandwidth and signal-to-noise ratio, which clearly define the limitations of the presented method.

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Section: Inversion Results With a Coherence-based Frequency Selectionmentioning

confidence: 99%

An experimental demonstration of blind ocean acoustic tomography

Jesus

Soares

Coelho

et al. 2006

The Journal of the Acoustical Society of America

View full text Add to dashboard Cite

show abstract

“…Battle et al (2003) used a towed array and the noise radiated by the towing ship's propeller to estimate the geo-acoustic properties of the bottom in a variable-range environment. Jesus et al (2002) and Mecklenbrauker & Gershman (2001) used a vertical linear array and a distant ship as a source to perform matched-field processing, with the known position of the ship assumed to be constant during the recording phase and matched-field processing adapted to the most powerful frequencies of radiated noise. Heaney (2004) andKuperman (1999) used towed arrays or a single hydrophone to record the transmitted field when the ship performed a transect centred on the array.…”

Section: Passive Acoustic Tomography: Review and New Conceptsmentioning

confidence: 99%

Passive acoustic tomography: new concepts and applications using marine mammals: a review

et al. 2007

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This paper presents the new concept of passive acoustic tomography which allows ocean data collection with a passive acoustic remote sensing process. The originality lies in using acoustic sources of opportunity such as surface noise, radiated ship noise and marine mammal calls. Such use of passive tomography is a promising way to reduce acoustic emissions in oceans. A review is first presented, including the description of new concepts of covert active, assisted passive and autonomous tomography, followed by applications on real world data. Under the assumptions of multipath propagation and measurements performed by a sparse network of hydrophones, a time–frequency processor is proposed to simultaneously estimate the source location and the impulse response of the propagation channel for marine mammal calls used as opportunistic sources (multipath structure, time delay and attenuation are estimated). Promising results are obtained on real data coming from the Laurentian channel where wideband beluga calls (1 to 3 kHz) are measured by a sparse network of 6 bottom hydrophones.

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Shallow water tomography in a highly variable scenario

Soares

Jesus

Coelho

2006

Acoustic Sensing Techniques for the Shallow Water Environment

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In October 2000, SiPLAB and the Instituto Hidrografico (IH -PN) conducted the IN-TIFANTE'00 sea trial in a shallow area off the Peninsula of Troia, approximately 50 kḿ south from Lisbon, in Portugal. The experiment itself and results obtained in most of the data set have been reported at various occasions in the last two years. This paper focuses on the data acquired during Event 2, where the acoustic propagation path was approximately range independent and the source ship was held on station at a constant range of 5.8 km from the vertical line array. Although these conditions were, in general, relatively benign for matched-field tomography, retrieval of water column and bottom parameters over a 14-hour-long recording revealed to be extremely difficult. This paper analysis in detail the characteristics of this data set and determines the causes for the observed inversion difficulties. Is is shown that the causes for the poor performance of the conventional methods are mainly the tide induced spatially correlated noise and the relative source-receiver motion during time averaging. An eigenvalue-based criterion is proposed for detecting optimal averaging time. It is shown that this data selection procedure together with hydrophone normalization and an appropriate objective function provide a better model fit and consistent inversion results and thus a better understanding of the environmental variability.

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Experimental Testing of the Blind Ocean Acoustic Tomography Concept

Cited by 4 publications

References 7 publications

An experimental demonstration of blind ocean acoustic tomography

An experimental demonstration of blind ocean acoustic tomography

Passive acoustic tomography: new concepts and applications using marine mammals: a review

Shallow water tomography in a highly variable scenario

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