Adaptive acoustic beamforming in a turbulent atmosphere

Area of Science:

• Acoustics
• Signal Processing
• Atmospheric Science

Background:

• Acoustic beamforming is crucial for source localization and bearing determination.
• Atmospheric turbulence, including wind and temperature fluctuations, significantly degrades conventional beamformer performance by altering signal amplitude and phase.
• Existing beamforming techniques often neglect these atmospheric effects in their theoretical and practical designs.

Purpose of the Study:

• To develop a mathematical framework to suppress amplitude and phase fluctuations caused by atmospheric turbulence.
• To enable the application of existing beamforming techniques in turbulent environments without performance degradation.
• To mitigate the impact of atmospheric turbulence on acoustic array performance.

Main Methods:

• A novel mathematical framework was formulated to suppress signal amplitude and phase fluctuations.
• The framework was constrained to a single source and the monochromatic plane wave approximation.
• The proposed approach was applied to an experimental setup involving acoustic arrays.

Main Results:

• The framework successfully suppressed phase and amplitude fluctuations with spatial scales smaller than the acoustic array aperture.
• Larger-scale fluctuations, causing random wavefront tilt, were not fully suppressed.
• Residual wavefront tilt led to errors in line-of-bearing estimates.

Conclusions:

• The developed framework effectively mitigates certain atmospheric turbulence effects on acoustic beamforming.
• Further research is needed to address larger-scale turbulence-induced wavefront distortions for improved bearing accuracy.
• This work provides a foundation for more robust acoustic sensing in challenging atmospheric conditions.