Forward scattering detection of a submerged object by a vertical hydrophone array.

Area of Science:

• Underwater acoustics
• Signal processing
• Oceanography

Background:

• Acoustic field aberrations from submerged objects are often masked by strong direct blast signals.
• Detecting these weak signals is crucial for underwater object identification and monitoring.

Purpose of the Study:

• To develop and validate a method for detecting acoustic field aberrations caused by forward scattering from submerged objects.
• To enhance the visibility of weak scattering signals above background noise and direct blast interference.

Main Methods:

• A lake experiment utilizing a 10 kHz pulse and a vertical hydrophone array spanning the water column.
• Application of time-delay beamforming to the hydrophone array data.
• Principal component analysis (PCA) applied to the stable portion of the beam output to isolate signal components.

Main Results:

• The study successfully detected acoustic field aberration, with variations up to 3 dB around the direct blast.
• PCA analysis, specifically the second principal component, effectively reduced the invariant direct blast component.
• Forward scattering aberration signals were amplified by up to 10 dB above the background acoustic field.

Conclusions:

• Time-delay beamforming combined with PCA is an effective technique for detecting weak acoustic aberrations from submerged objects.
• This method significantly enhances the signal-to-noise ratio, improving the detection of forward-scattered acoustic fields.
• The findings have implications for underwater surveillance, acoustic imaging, and marine environment monitoring.