Broadband source localization using horizontal-beam acoustic intensity striations.

Area of Science:

• Underwater acoustics
• Oceanography
• Signal processing

Background:

• Ship noise localization is crucial for maritime surveillance and environmental monitoring.
• Horizontal Line Array (HLA) beamforming offers potential for acoustic source localization.
• Understanding sound propagation in shallow waters, influenced by bathymetry, is complex.

Purpose of the Study:

• To apply waveguide invariant theory to HLA beamformer output for localizing moving broadband noise sources.
• To estimate the waveguide invariant parameter 'beta' and source range/speed ratio using acoustic intensity striation patterns.
• To validate the localization technique using data from multiple receivers and HLA beam-time records.

Main Methods:

• Utilized waveguide invariant theory applied to Horizontal Line Array (HLA) beamformer output.
• Employed Hough transforms to analyze acoustic intensity striation patterns and estimate 'beta' and range/speed ratio.
• Collected simultaneous acoustic data from an HLA and three hydrophones during the RAGS03 experiment.

Main Results:

• Successfully demonstrated source localization capability for moving broadband noise sources (50-150 Hz).
• Validated the estimation of the waveguide invariant parameter 'beta' using acoustic data.
• Observed influence of range-dependent bathymetry on acoustic intensity striation patterns.

Conclusions:

• The combined approach of waveguide invariant theory and Hough transforms is feasible for locating broadband noise sources in shallow waters.
• The method provides reliable estimation of the waveguide invariant parameter 'beta'.
• Cross-validation with multiple data sources confirms the robustness of the localization technique.