Bioinspired Covert Sonar Signal Waveform Design Using Phase Coding of Sperm Whale Clicks for Underwater Sensor Platforms

Low probability of intercept (LPI) and low probability of detection (LPD) strategies face challenges in enhancing the effective detection range while maintaining covertness. In order to address this issue, a bioinspired covert strategy has been proposed and investigated. This approach leverages the original or modified sounds of marine mammals as sonar signals to deceive enemy recognition systems. Based on this strategy, the sperm whale (physeter macrocephalus)—a widely distributed marine species—was chosen as the biomimetic subject due to its distinctive clicks. However, individual sperm whale click signals exhibit limitations in detection performance and covertness. In order to address these limitations, a bioinspired covert sonar (BCS) signal waveform design approach using phase coding of sperm whale clicks was developed. The proposed method enables simple construction through minor signal modifications while mimicking the pseudo-periodic modulation patterns of natural click trains. This study also analyzes critical parameters influencing signal detection performance. Simulation and experimental results demonstrate the superiority of the proposed method in terms of detection effectiveness and covertness.