Parametric spatial post-filtering utilising high-order circular harmonics with applications to underwater sound-field...

Area of Science:

• Acoustics
• Signal Processing
• Underwater Acoustics

Background:

• Beamforming with circular hydrophone arrays is used for 2D underwater sound-field visualization.
• Traditional beamformers face limitations in spatial selectivity, especially with higher-order harmonic inputs.

Purpose of the Study:

• To propose a parametric spatial post-filtering method for large circular arrays.
• To enhance the spatial selectivity of traditional beamformers.
• To extend the applicability of the cross-pattern coherence (CroPaC) spatial post-filter to higher-order harmonic inputs.

Main Methods:

• Reformulation of the cross-pattern coherence (CroPaC) spatial post-filter.
• Calculation of normalized cross-spectral density between signals from coincident beamformers.
• Application of the post-filter to sharpen beamformers and attenuate noise and interferers.

Main Results:

• The proposed reformulation extends CroPaC's applicability to higher-order circular harmonic inputs.
• Evaluated with simulated data from a 96-channel circular hydrophone array.
• Demonstrated improvement in spatial selectivity for both delay-and-sum and minimum-variance distortionless response beamformers.

Conclusions:

• The proposed spatial post-filter effectively improves the spatial selectivity of beamformers in passive sonar scenarios.
• The method offers enhanced performance for underwater sound-field visualization with large circular arrays.