Resolution of matched field processing for a single hydrophone in a rigid waveguide

Area of Science:

• Underwater acoustics
• Signal processing
• Geophysical exploration

Background:

• Accurate localization of underwater acoustic sources is crucial for various applications, including navigation, resource exploration, and environmental monitoring.
• Matched field processing (MFP) is a widely used technique for source localization, but its resolution is often limited by environmental factors and data availability.
• Understanding the factors affecting MFP resolution, such as waveguide properties and signal characteristics, is essential for improving localization accuracy.

Purpose of the Study:

• To investigate the resolution of matched field processing for range and depth localization of broadband underwater acoustic sources.
• To derive analytical approximations for the main-lobe widths of the ambiguity surface in an ideal rigid shallow-water waveguide.
• To analyze the impact of different measurement types (coherent pressure vs. pressure magnitude-squared) on localization resolution.

Main Methods:

• Utilized the normal-mode expansion for the acoustic pressure field in a shallow-water waveguide.
• Derived approximate expressions for ambiguity surface main-lobe widths as a function of the number of modes and frequency band.
• Conducted numerical simulations to corroborate analytical findings and explore realistic Pekeris waveguide environments.

Main Results:

• Provided analytical approximations for the main-lobe widths of the ambiguity surface, offering insights into the resolution limits of MFP.
• Demonstrated that resolution is dependent on the number of acoustic modes and the frequency band of the source signal.
• Showcased numerical simulations of MFP ambiguity surfaces in realistic shallow-water environments, validating the analytical approach.

Conclusions:

• The derived analytical expressions offer valuable predictions for MFP resolution in shallow-water waveguides.
• The study highlights the importance of signal characteristics and waveguide properties in determining localization accuracy.
• The ambiguity analysis provides a framework for understanding MFP performance in both ideal and realistic underwater environments, including Pekeris waveguides.