An Improved Velocity Estimation Method for Wideband Multi-Highlight Target Echoes in Active Sonar Systems.

Area of Science:

• Acoustics
• Signal Processing
• Marine Technology

Background:

• Active sonar systems face challenges in velocity estimation due to Doppler-scaled reflections from multiple target highlights overlapping in time and frequency.
• Hyperbolic-frequency modulated (HFM) signals are used for moving targets due to Doppler tolerance, but precise velocity estimation remains difficult.

Purpose of the Study:

• To model target echoes considering multi-highlights and constant velocity in active sonar.
• To analyze velocity estimation performance using conventional methods like matched filters and wideband ambiguity functions.
• To propose and evaluate an improved velocity estimation method for HFM signals in sonar systems.

Main Methods:

• Modeling sonar echoes as a superposition of Doppler-scaled reflections from multi-highlights.
• Analyzing velocity estimation performance with matched filters and wideband ambiguity functions.
• Developing an improved method using a sliding window matching algorithm with a designed window that exploits HFM signal Doppler characteristics.

Main Results:

• The study confirms that multi-highlights significantly influence velocity estimation performance in sonar.
• The proposed sliding window method effectively controls noise and interference by focusing on dominant target highlights.
• Simulations and lake experiments demonstrate the superior performance of the improved method compared to conventional matched filters.

Conclusions:

• The multi-highlight nature of target echoes is a critical factor affecting sonar velocity estimation accuracy.
• The developed sliding window matching algorithm offers a more effective approach for precise velocity estimation with HFM signals in challenging sonar environments.
• This improved method enhances the reliability of velocity estimation for moving targets in active sonar applications.