Effects of atmospheric refraction on detecting elevated sources with beamforming algorithms

Area of Science:

• Acoustics
• Signal Processing
• Atmospheric Physics

Background:

• Classical beamforming assumes rectilinear signal propagation, which is inaccurate in atmospheric conditions.
• Atmospheric effects like refraction, turbulence, and scattering degrade acoustic system performance.
• Understanding these effects is crucial for developing robust acoustic detection systems.

Purpose of the Study:

• To investigate the impact of atmospheric refraction on beamforming algorithm performance.
• To evaluate whether incorporating atmospheric effects improves acoustic detection accuracy.
• To assess the limitations of current signal processing algorithms in real-world atmospheric scenarios.

Main Methods:

• Simulated signal propagation from elevated sources to a ground microphone array.
• Tested four standard beamforming algorithms with and without atmospheric refraction model errors.
• Evaluated detection performance using the area under the receiver operating characteristic curve (AUC).

Main Results:

• No significant improvement in detection performance was observed when refraction effects were included in beamforming algorithms.
• Any minor gains from incorporating refraction were overshadowed by turbulence and scattering.
• The inclusion of refraction effects was deemed unnecessary ('over-engineering') for the tested scenario.

Conclusions:

• Atmospheric refraction alone does not significantly enhance beamforming performance in acoustic systems.
• Turbulence and surface scattering are dominant factors limiting detection performance.
• Current signal processing and array design approaches may need re-evaluation for atmospheric acoustic applications.