A wavefront adaptive sensing beamformer for ocean acoustic waveguides.

Area of Science:

• Acoustics
• Signal Processing
• Ocean Engineering

Background:

• Conventional beamforming is prevalent in passive sonar but struggles with signal mismatch in complex, multipath environments.
• Existing robust adaptive beamforming methods often reduce adaptivity and fail to suppress interference adequately due to added constraints.
• Uncertainty in signal subspace modeling limits the effectiveness of traditional adaptive beamformers in dynamic underwater settings.

Purpose of the Study:

• To develop a robust adaptive beamformer for passive sonar systems operating in uncertain shallow-water environments.
• To enhance target separation from strong interference by avoiding traditional modeling constraints.
• To improve the performance of passive sonar in complex acoustic conditions.

Main Methods:

• Utilizes blind source separation techniques to adaptively estimate spatial wavefronts of targets and interference.
• Exploits differences in temporal spectra and frequency-selective multipath fading between targets and interference.
• Constructs a signal-free covariance matrix without imposing directional gain constraints, leading to the wavefront adaptive sensing (WAS) beamformer.

Main Results:

• The wavefront adaptive sensing (WAS) beamformer successfully separates targets from strong interference, even when the interference is within the target's conventional beam width.
• Simulation results in realistic shallow-water channels demonstrate superior performance.
• Validation using SWellEx96 S59 data with an injected target confirms the WAS beamformer's effectiveness.

Conclusions:

• The proposed wavefront adaptive sensing (WAS) beamformer offers a significant advancement for passive sonar in challenging shallow-water environments.
• By leveraging blind source separation, WAS overcomes limitations of conventional and existing robust adaptive beamformers.
• This approach provides enhanced target detection and interference suppression capabilities crucial for underwater acoustic applications.