Multistatic detection and tracking using linear maximal sequences

Area of Science:

• Acoustic signal processing
• Underwater target detection

Background:

• Detecting and tracking near-surface targets in shallow water presents challenges due to multipaths, clutter, and reverberation.
• Traditional methods for interference rejection may not be sufficient in complex acoustic environments.

Purpose of the Study:

• To evaluate the potential of linear maximal sequence (m-sequence) transmissions for near-surface target detection and tracking.
• To demonstrate the effectiveness of novel processing techniques in improving signal-to-interference ratio for acoustic tracking.

Main Methods:

• A simulation was conducted in 4m deep water using a low-power, omnidirectional source and four omnidirectional hydrophones.
• Linear maximal sequence (m-sequence) transmissions were employed for signal generation.
• Channel digit response processing and block zeroing were utilized to reject direct arrivals, multipaths, clutter, and reverberation.

Main Results:

• The simulation demonstrated successful rejection of direct arrivals, multipaths, clutter, and reverberation.
• An improved signal-to-interference ratio was achieved through the applied processing techniques.
• A simple probability-based algorithm successfully tracked a simulated -15 dB target at distances up to 250 meters.

Conclusions:

• Linear maximal sequence (m-sequence) transmissions show significant potential for detecting and tracking near-surface underwater targets.
• The combination of channel digit response processing and block zeroing offers a robust method for interference mitigation in shallow water acoustics.
• The developed approach enables effective target tracking even in challenging acoustic environments with limited signal strength.