An Improved Time Delay Measurement Method for the Long-Distance Underwater Environment.

Area of Science:

• Oceanography
• Signal Processing
• Acoustics

Background:

• Accurate time delay measurements are crucial for underwater navigation and communication.
• Long-distance underwater signal propagation presents challenges due to signal degradation and channel variability.
• Existing methods struggle to achieve high accuracy in these conditions, especially with low signal-to-noise ratios (SNR).

Purpose of the Study:

• To develop an improved, high-accuracy time delay measurement method for long-distance underwater channel propagation.
• To enhance the robustness of time delay estimation in challenging underwater acoustic environments.
• To contribute to advancements in underwater navigation and communication systems.

Main Methods:

• Signal acquisition using encoded signals at the receiver.
• Bandpass filtering to improve signal-to-noise ratio (SNR).
• An optimal time window selection strategy for cross-correlation in dynamic underwater channels.
• Novel cross-correlation calculation regulations.

Main Results:

• The proposed method demonstrated high accuracy in time delay measurements, with errors around 10⁻³ seconds.
• Effectiveness was verified through comparison with other algorithms under low SNR conditions using Bellhop simulation data.
• Successful validation through underwater experiments over various distances.

Conclusions:

• The developed method provides a significant improvement in time delay measurement accuracy for long-distance underwater propagation.
• The technique is effective even in low SNR environments, addressing a key challenge in underwater acoustics.
• This advancement supports the development of more reliable underwater navigation and communication systems.