scholarly journals Symmetry Oriented Covert Acoustic Communication by Mimicking Humpback Whale Song

Symmetry ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 752 ◽  
Author(s):  
Gang Qiao ◽  
Muhammad Bilal ◽  
Songzuo Liu ◽  
Tianlong Ma ◽  
Yunjiang Zhao ◽  
...  
Keyword(s):  
Acoustic Communication ◽  
Matching Pursuit ◽  
Signal To Noise Ratio ◽  
Humpback Whale ◽  
Underwater Acoustic Communication ◽  
Covert Communication ◽  
Underwater Acoustic ◽  
Communication Signal ◽  
Tank Experiment ◽  
Novel Concept

To meet the increasing demand of covert underwater acoustic communication, biologically inspired mimicry communication watermarking the data in symmetrical humpback whale song is presented. Mimicry is an entirely different approach from traditional covert communication where data are transmitted by spreading the waveform at a low signal to noise ratio. In this innovative technique, the carrier signal is imitated symmetrical to the ocean background noise, which can be shipping noise, anthropological noise, or the vocals emitted by sea animals. The eavesdropper can detect the communication signal, but will assume it to be real ocean noise due to its symmetry. It excludes the mimicked signal from recognition, which makes the communication covert. In this research, we watermarked the covert information in humpback whale song using discrete cosine transform in the frequency domain. The mimicked symmetrical signal provided excellent imperceptibility with the real song and an outstanding camouflage effect was calculated. We validated the novel concept by simulation and underwater tank experiment. 10−4 BER was achieved in the underwater tank experiment, which was diminished to zero error by using matching pursuit estimation and virtual time reversal equalization. This novel bionic covert communication technique is feasible for clandestine underwater acoustic communication in the presence of an eavesdropper with better imperceptibility.

scholarly journals Bionic Morse Coding Mimicking Humpback Whale Song for Covert Underwater Communication

2019 ◽  
Vol 10 (1) ◽  
pp. 186 ◽  
Author(s):  
Bilal ◽  
Liu ◽  
Qiao ◽  
Wan ◽  
Tao
Keyword(s):  
Acoustic Communication ◽  
English Language ◽  
Matching Pursuit ◽  
Signal To Noise Ratio ◽  
Humpback Whale ◽  
Humpback Whales ◽  
Underwater Acoustic Communication ◽  
Underwater Acoustic ◽  
Transmission Distance ◽  
Communication Signal

A novel method of bionic Morse coding mimicking humpback whale vocal is presented for covert underwater acoustic communication. The complex humpback whale song is translated as bionic Morse codes based on information entropy. The communication signal is made akin to the natural singing of male humpback whales. The intruder can detect the signal but will not be able to recognize the communication signal due to unified resemblance with the natural sound. This novel technique gives an excellent low probability of recognition characteristics. A flawless stealthy underwater acoustic communication has been established which has negligible chances of deciphered with high imperceptibility. Standard mimicry Morse codes have been developed for the characters of the English language and compared with Morse coding. Covert information of one character per second can be watermarked with perfect stealth and clandestine communication. This novel concept has been verified at transmission distance of five km and less than 10−3 Bit Error Rate (BER) is achieved at Signal to Noise Ratio (SNR) down to negative seven dB. Zero BER is attained by estimating the channel by a matching pursuit algorithm and equalizing the errors by virtual time reversal mirror technique.

scholarly journals Demodulation of Chaos Phase Modulation Spread Spectrum Signals Using Machine Learning Methods and Its Evaluation for Underwater Acoustic Communication

Sensors ◽  
2018 ◽  
Vol 18 (12) ◽  
pp. 4217
Author(s):  
Chao Li ◽  
Franck Marzani ◽  
Fan Yang
Keyword(s):  
Machine Learning ◽  
Acoustic Communication ◽  
Spread Spectrum ◽  
Phase Modulation ◽  
Direct Sequence Spread Spectrum ◽  
Propagation Loss ◽  
Underwater Acoustic Communication ◽  
Processing Unit ◽  
Underwater Acoustic ◽  
Communication Signal

The chaos phase modulation sequences consist of complex sequences with a constant envelope, which has recently been used for direct-sequence spread spectrum underwater acoustic communication. It is considered an ideal spreading code for its benefits in terms of large code resource quantity, nice correlation characteristics and high security. However, demodulating this underwater communication signal is a challenging job due to complex underwater environments. This paper addresses this problem as a target classification task and conceives a machine learning-based demodulation scheme. The proposed solution is implemented and optimized on a multi-core center processing unit (CPU) platform, then evaluated with replay simulation datasets. In the experiments, time variation, multi-path effect, propagation loss and random noise were considered as distortions. According to the results, compared to the reference algorithms, our method has greater reliability with better temporal efficiency performance.

Numerical Simulation and Experimental Research of Hydrophone Flow Noise

2020 ◽  
Author(s):  
Mingyuan Li ◽  
Jianzhang Liu ◽  
Yan Wei ◽  
Fengzhong Qu ◽  
Minhao Zhang ◽  
...  
Keyword(s):  
Flow Field ◽  
Acoustic Communication ◽  
Communication System ◽  
Signal To Noise Ratio ◽  
Low Frequency ◽  
Sound Field ◽  
Underwater Acoustic Communication ◽  
Acoustic Analogy ◽  
Underwater Acoustic ◽  
Flow Noise

Abstract Underwater acoustic communication is an important technology in deep-sea research. In underwater acoustic communication system, when hydrophone as acoustic receiver is exposed to sea environment and moves along with an underwater vehicle, its performance is prone to be affected by various ambient noises, among which its generated flow noise is the major source. This would especially influence the performance and shorten the communication distance of underwater acoustic communication system. In this paper, we try to unveil how the flow field is correlated with the flow noise of hydrophone. The Large Eddy Simulation (LES) method and acoustic analogy were used to simulate the flow field and the sound field around hydrophone, respectively. The flow noise of hydrophone at different moving velocities was obtained. Then experiments in an anechoic tank were carried out to verify the simulation results. The subsequent analysis of the experimental results shows that the flow noise has obvious influence on underwater communication, and as the hydrophone moves faster, its sound pressure level climbs up higher. This study also further verifies the reliability of simulating the flow noise of bare hydrophone by computational fluid dynamics, and provides the theoretical basis for improving the signal-to-noise ratio of low-frequency underwater acoustic communication system.

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