Estimation of the roll angle in a triplet towed array using oceanic surface-generated ambient noise.

Area of Science:

• Ocean Acoustics
• Array Signal Processing
• Geophysical Measurement

Background:

• Accurate orientation estimation is crucial for towed array hydrophone systems.
• Traditional methods often require detailed environmental information or external sensors.
• Ocean ambient noise, particularly in the 1-10 kHz range, contains valuable directional information.

Purpose of the Study:

• To propose and validate a new method for estimating the roll angle of a triplet towed array.
• To utilize mid-frequency oceanic ambient noise for passive roll-angle determination.
• To assess the method's performance and dependency on environmental conditions.

Main Methods:

• The method employs the ratio of approximated phase parts of the noise-coherence function between triplet hydrophones.
• It leverages mid-frequency (1-10 kHz) oceanic ambient noise, dominated by surface-generated sources.
• The technique does not require explicit oceanic environmental input for uniform or end-fire noise fields.

Main Results:

• The proposed roll-angle estimation method was applied to data collected in the East Sea of Korea.
• Estimated roll angles showed good agreement with roll-sensor data, with a root mean square error of 10°.
• The accuracy of the estimation improved with increasing wind speed, reducing the difference between estimated and measured angles.

Conclusions:

• The developed technique offers a viable passive method for roll-angle estimation in towed arrays.
• Its robustness in certain noise field conditions reduces reliance on external environmental data.
• The method demonstrates practical applicability and potential for enhancing towed array system performance.