A Matched Subspace Approach to Depth Discrimination in a Shallow Water Waveguide

Premus, V.; Backman, Daniel

doi:10.1109/acssc.2007.4487430

Cited by 19 publications

(18 citation statements)

References 2 publications

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“…In most shallow water environments that we have analyzed, the continuous noise spectrum, i.e., noise not associated with a narrowband tonal or other discrete spectrum feature, typically tests slightly positive for submergence using the matched subspace discriminator. 16 This is consistent with the phenomenon of path stripping, in which the noise from distant shipping borne by steep propagation paths is more rapidly attenuated relative to that borne by axial propagation paths due to the greater number of bottom interactions encountered by high angle multipath. Path stripping will thus tend to impact the high order subspace more, making noise from distant shipping look more submerged with range.…”

Section: B Measured Depth Discrimination Resultssupporting

confidence: 76%

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Use of mode subspace projections for depth discrimination with a horizontal line array: Theory and experimental results

Premus

Helfrick²

2013

The Journal of the Acoustical Society of America

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A solution to the problem of acoustic source depth discrimination in a downward refracting, shallow-water ocean waveguide is presented for the case of a horizontal line array at endfire. The approach exploits the phenomenon of mode trapping, wherein a shallow acoustic source cannot excite the lowest order waveguide modes due to its evanescent amplitude dependence near the surface. The important implication of this "trapping" behavior is that, given sufficient spatial aperture, it provides a mechanism for differentiating a shallow acoustic noise source from one at depth. The method does not require array cant, or physical vertical aperture of any kind, but instead relies only on the sensitivity of a line array at endfire to differences in horizontal wave number to resolve low and high order mode subspace excitations. The only inputs to the algorithm are an approximate sound speed profile, water depth, and bottom type. The theoretical basis for the test statistic is first reviewed, followed by discussion of key requirements, and illustration of the concept using results from a RAM PE simulation for a downward refracting environment. Finally, the algorithm is experimentally demonstrated using data from a bottom-mounted HLA deployed in the moderately cluttered continental shelf environment of the Florida Straits.

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Section: B Measured Depth Discrimination Resultssupporting

confidence: 76%

“…This approach has already been experimentally demonstrated for the case of a sparse VLA aperture. 16 Here, we extend the development in Ref. 16 to the case of the HLA.…”

Section: The Matched Subspace Discriminatormentioning

confidence: 92%

Use of mode subspace projections for depth discrimination with a horizontal line array: Theory and experimental results

Premus

Helfrick²

2013

The Journal of the Acoustical Society of America

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“…In the first group, Premus et al proposed a matched subspace method to depth discrimination [6,7]. They used the difference in energy projected in the mode subspace between the shallow source and the deep one.…”

Section: Related Workmentioning

confidence: 99%

“…However, SI can be used to discriminate source depth only if those ranges are sufficiently close, since it is influenced by the source-receiver range besides source depth. Considering the ill-posed problem of mode filtering when the water column is not well-sampled by the VLA, Conan et al [9] proposed a robust method for discriminating the source depth supported by previous work introduced in [6,7,8]. When the VLA spans only 50% of the water column, that method outperforms those proposed in [6,7], as is evaluated by the receiver operating characteristic curve.…”

Section: Related Workmentioning

confidence: 99%

“…However, the frequency of the moving source must be known a priori, which is difficult with passive sonar system. Next, unlike the first approach based on depth estimation, the second approach considers depth discrimination as a binary hypothesis test; examples include the matched-subspace method [6,7], the scintillation index (SI) [8], and the trapped energy ratio [9] to improve the robustness of depth discrimination.…”

Section: Introductionmentioning

confidence: 99%

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Depth Discrimination for Low-Frequency Sources Using a Horizontal Line Array of Acoustic Vector Sensors Based on Mode Extraction

Liang

Zhang

et al. 2018

Sensors

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Depth discrimination is a key procedure in acoustic detection or target classification for low-frequency underwater sources. Conventional depth-discrimination methods use a vertical line array, which has disadvantage of poor mobility due to the size of the sensor array. In this paper, we propose a depth-discrimination method for low-frequency sources using a horizontal line array (HLA) of acoustic vector sensors based on mode extraction. First, we establish linear equations related to the modal amplitudes based on modal beamforming in the vector mode space. Second, we solve the linear equations by introducing the total least square algorithm and estimate modal amplitudes. Third, we select the power percentage of the low-order modes as the decision metric and construct testing hypotheses based on the modal amplitude estimation. Compared with a scalar sensor, a vector sensor improves the depth discrimination, because the mode weights are more appropriate for doing so. The presented linear equations and the solution algorithm allow the method to maintain good performance even using a relatively short HLA. The constructed testing hypotheses are highly robust against mismatched environments. Note that the method is not appropriate for the winter typical sound speed waveguide, because the characteristics of the modes differ from those in downward-refracting sound speed waveguide. Robustness analysis and simulation results validate the effectiveness of the proposed method.

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Difference Factor of Vertical Beam Pattern for Shallow-Water Source Depth Discrimination

Zheng

Zhu

2021

Acoust Aust

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A Matched Subspace Approach to Depth Discrimination in a Shallow Water Waveguide

Cited by 19 publications

References 2 publications

Use of mode subspace projections for depth discrimination with a horizontal line array: Theory and experimental results

Use of mode subspace projections for depth discrimination with a horizontal line array: Theory and experimental results

Depth Discrimination for Low-Frequency Sources Using a Horizontal Line Array of Acoustic Vector Sensors Based on Mode Extraction

Difference Factor of Vertical Beam Pattern for Shallow-Water Source Depth Discrimination

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