Covert underwater acoustic communications

Area of Science:

• Underwater Acoustic Communications
• Signal Processing
• Information Security

Background:

• Covert communication systems aim for low probability of detection (LPD) or interception (LPI).
• Underwater acoustic (UWA) channels present unique challenges, including time-varying conditions and frequency selectivity.
• Direct-sequence spread-spectrum (DSSS) is crucial for achieving processing gain in LPD systems.

Purpose of the Study:

• To investigate a covert UWA communication system employing DSSS and a coherent RAKE receiver.
• To design a spreading waveform optimized for UWA channel characteristics and superior LPI.
• To evaluate the proposed techniques using simulated and experimental UWA data.

Main Methods:

• Utilized direct-sequence spread-spectrum (DSSS) technique.
• Employed a coherent RAKE receiver for signal processing.
• Developed and tested novel spreading waveforms tailored for UWA environments.
• Validated methods with simulated data and SPACE'08 in-water experimental data.

Main Results:

• Demonstrated the feasibility of covert UWA communication using DSSS.
• Showcased a spreading waveform design that balances UWA channel adaptation and LPI.
• Achieved successful communication in challenging underwater acoustic conditions.

Conclusions:

• The proposed DSSS-based system offers a viable solution for secure covert communications in UWA environments.
• Waveform design is critical for overcoming UWA channel impairments and ensuring low probability of interception.
• The study provides valuable insights for future secure UWA communication system development.