Biomimicking Covert Communication by Time-Frequency Shift Modulation for Increasing Mimicking and BER Performances

Area of Science:

• Underwater Acoustic Communications
• Biomimetic Systems
• Signal Processing

Background:

• Underwater acoustic (UWA) communications are crucial for covert operations.
• Achieving simultaneous high bit error rate (BER) and degree of mimic (DoM) in UWA covert communications presents a significant challenge.

Purpose of the Study:

• To propose a novel biomimicking covert communication method to simultaneously improve BER and DoM performances.
• To enhance the effectiveness of underwater covert communications through advanced signal processing techniques.

Main Methods:

• Development of a biomimicking covert communication method based on Time Frequency Shift Keying (TFSK).
• Theoretical derivation of orthogonality requirements for TFSK time- and frequency-shifting units.
• Multiplication of whistle signals with sequences exhibiting high correlation.
• Implementation of two-step DoM assessments for long-term whistle signals.

Main Results:

• The proposed method significantly increases DoM performance by 35%.
• A zero BER was achieved at a Signal to Noise Ratio (SNR) of -6 dB.
• Validation through computer simulations and practical lake and ocean experiments.

Conclusions:

• The novel TFSK-based biomimicking method effectively enhances both DoM and BER in UWA covert communications.
• The findings demonstrate a practical solution for robust and covert underwater communication systems.