The theoretical responses of vertical and horizontal line arrays to wind‐induced noise in shallow water

Due to the dispersion of normal modes in shallow water, there exist regular striations on the interference spectrogram in space-frequency domain. Based on the range-frequency domain striations, waveguide invariant can be estimated with the prior knowledge of source range. Utilizing striations along the array, Rouseff and Zurk [J. Acoust. Soc. Amer. 130 (2011) EL76–EL81] proposed the striation-based beamforming (SBF), which shows a theoretical possibility to estimate waveguide invariant that is independent of source range. To make this beamforming technique more practical, its application requirements and performance limitation should be defined. These two issues are researched with the phase and amplitude relationships deduced by the frequency-shift compensation theory. It shows the source whose spectrum varies slowly and received signals that contain the complete information of transmission time are keys for applying SBF to real work. The azimuth limitation can lead to the degradation of array gain and distortion of interference structure. Matching parameters of waveguide invariant and source range, respectively, two modified striation-based beamformers are developed to eliminate the azimuth limitation. Simulation and experimental results are presented.

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Moving Source Depth Estimation Using a Horizontal Line Array in Shallow Water Waveguides

10.20944/preprints201804.0148.v1 ◽

2018 ◽

Author(s):

Liang Guolong ◽

Zhang Yifeng ◽

Zou Nan ◽

Wang Jinjin

Keyword(s):

Shallow Water ◽

Estimation Method ◽

Depth Estimation ◽

Propagation Model ◽

Small Range ◽

Horizontal Line ◽

Source Depth ◽

Moving Source ◽

Line Array ◽

Wavenumber Spectrum

In this study, a matched-mode autoregressive source depth estimation method (MMAR) based on autoregressive (AR) wavenumber estimation is proposed for a moving source in shallow water waveguides. The signal original frequency and the environmental parameters, namely, the sound speed profile and bottom properties are known as a prior knowledge. The mode wavenumbers are estimated by the AR modal wavenumber spectrum. On the basis of the mode wavenumber estimation, the mode amplitudes can be estimated by the wavenumber spectrum that is obtained by generalized Hankel transform. The source depth estimation is determined by the peak of source depth function wherein the data mode best matches the replica mode that is calculated using a propagation model. Compared with other methods of moving source depth estimation, the proposed method exhibits a better performance in source depth estimation under low signal-to-noise ratio or the small range span. The selection of horizontal line array depth is illustrated by simulation and normal mode theory in details.

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Matched‐field processing of multi‐tone acoustic signals in shallow water with a horizontal line array

The Journal of the Acoustical Society of America ◽

10.1121/1.418632 ◽

1997 ◽

Vol 101 (5) ◽

pp. 3048-3048

Author(s):

Phil Schey ◽

Newell O. Booth ◽

Gary Dorrance ◽

Al Aburto ◽

William S. Hodgkiss

Keyword(s):

Shallow Water ◽

Acoustic Signals ◽

Horizontal Line ◽

Matched Field Processing ◽

Line Array

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Match-Mode Autoregressive Method for Moving Source Depth Estimation in Shallow Water Waveguides

Mathematical Problems in Engineering ◽

10.1155/2018/7824671 ◽

2018 ◽

Vol 2018 ◽

pp. 1-15 ◽

Cited By ~ 1

Author(s):

Liang Guo-Long ◽

Zhang Yi-Feng ◽

Zou Nan ◽

Wang Jin-Jin

Keyword(s):

Shallow Water ◽

Depth Estimation ◽

Propagation Model ◽

Estimation Methods ◽

Small Range ◽

Horizontal Line ◽

Source Depth ◽

Moving Source ◽

Line Array ◽

Wavenumber Spectrum

Source depth estimation is always a problem in underwater acoustic area, because depth estimation is a nonlinear problem. Traditional depth estimation methods use a vertical line array, which has disadvantage of poor mobility due to the size of sensor array. In order to estimate source depth with a horizontal line array, we propose a matched-mode depth estimation method based on autoregressive (AR) wavenumber estimation for a moving source in shallow water waveguides. First, we estimate the mode wavenumbers using the improved AR modal wavenumber spectrum. Second, according to the mode wavenumber estimation, we estimate the mode amplitudes by the wavenumber spectrum, which is obtained by generalized Hankel transform. Finally, we estimate source depth estimation by the peak of source depth function wherein the data mode best matches the replica mode that is calculated using a propagation model. Compared with synthetic aperture beamforming, the proposed method exhibits a better performance in source depth estimation under low signal-to-noise ratio or the small range span. The robustness of the proposed method is illustrated by simulating the performance in mismatched environment.

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