Performance bounds for passive sensor arrays operating in a turbulent medium: plane-wave analysis.

Area of Science:

• Acoustics
• Wave Propagation
• Statistical Signal Processing

Background:

• Passive acoustic arrays are crucial for source localization.
• Turbulent media introduce significant challenges to wave propagation.
• Understanding performance bounds is essential for array design and application.

Purpose of the Study:

• Investigate performance bounds of passive acoustic arrays in turbulent media.
• Analyze Cramer-Rao lower bounds for angle-of-arrival estimation.
• Examine the impact of propagation distance, turbulence, and signal-to-noise ratio on estimation accuracy.

Main Methods:

• Utilized a von Kármán spectrum to model turbulence.
• Considered a single, monochromatic, plane-wave source at near-normal incidence.
• Calculated Cramer-Rao lower bounds in both two and three dimensions.

Main Results:

• Cramer-Rao lower bounds for angles of arrival increase with index-of-refraction variance and normalized propagation distance.
• Signal-to-noise ratio is the limiting factor for small turbulence and propagation distances.
• In 2D, angle-of-arrival estimates can decouple from other parameters with optimal array geometry.
• In 3D, azimuth and elevation estimates decouple from other parameters but remain coupled to each other.

Conclusions:

• Turbulence and propagation distance significantly degrade angle estimation accuracy in passive acoustic arrays.
• Signal-to-noise ratio is critical for accurate localization in less turbulent environments.
• Array geometry plays a vital role in optimizing parameter estimation in turbulent media.