In underwater acoustic communication (UAC) systems, the channel characteristics are mainly affected by spatiotemporal changes, which are specifically manifested by two factors: the effects of refraction and scattering caused by seawater layered media on the sound field and the random fluctuations from the sea floor and surface. Due to the time-varying and space-varying characteristics of a channel, the communication signals have significant variations in time and space. Furthermore, the signal shows frequency-selective fading in the frequency domain and signal waveform distortion in the time domain, which seriously affect the performance of a UAC system. Techniques such as error correction coding or space diversity are usually adopted by UAC systems to neutralize or eliminate the effects of deep fading and signal distortion, which results in a significant waste of limited communication resources. From the perspective of the sound field, this study used experimental data to analyze the spatiotemporal fluctuation characteristics of the signal and noise fields and then summarized the temporal and spatial variation rules. The influence of the system then guided the parameter configuration and network protocol optimization of the underwater acoustic communication system by reasonably selecting the communication signal parameters, such as frequency, bandwidth, equipment deployment depth, and horizontal distance.
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http://dx.doi.org/10.3390/s22155795 | DOI Listing |
PeerJ
January 2025
Institute of Science and Environment, University of Saint Joseph, Macao, Macao S.A.R., China.
While soundscapes shape the structure and function of auditory systems over evolutionary timescales, there is limited information regarding the adaptation of wild fish populations to their natural acoustic environments. This is particularly relevant for freshwater ecosystems, which are extremely diverse and face escalating pressures from human activities and associated noise pollution. The Siamese fighting fish is one of the most important cultured species in the global ornamental fish market and is increasingly recognized as a model organism for genetics and behavioural studies.
View Article and Find Full Text PDFJ Acoust Soc Am
January 2025
Key Laboratory of Underwater Acoustic Communication and Marine Information Technology of the Ministry of Education, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361005, China.
Odontocetes are capable of dynamically changing their echolocation clicks to efficiently detect targets, and learning their clicking strategy can facilitate the design of man-made detecting signals. In this study, we developed deep convolutional generative adversarial networks guided by an acoustic feature vector (AF-DCGANs) to synthesize narrowband clicks of the finless porpoise (Neophocaena phocaenoides sunameri) and broadband clicks of the bottlenose dolphins (Tursiops truncatus). The average short-time objective intelligibility (STOI), spectral correlation coefficient (Spe-CORR), waveform correlation coefficient (Wave-CORR), and dynamic time warping distance (DTW-Distance) of the synthetic clicks were 0.
View Article and Find Full Text PDFJ Acoust Soc Am
January 2025
Department of Physics, Naval Postgraduate School, 833 Dyer Road, Monterey, California 93943-5216, USA.
The shear wave speed is often small compared to the compressional wave speed in the top part of the seabed, where acoustic normal modes penetrate. In sediments with weak but finite shear rigidity, the strongest conversion from compressional to shear waves occurs at interfaces within the sediment. Shear wave generation at such interfaces and interference within sediment layers lead to first-order perturbations in the normal mode phase speed and contributions to sound attenuation, which vary rapidly with frequency.
View Article and Find Full Text PDFJ Acoust Soc Am
January 2025
College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, 310027, China.
High-efficiency electromagnetic transducers are crucial for enabling the self-sustained operation of underwater electromagnetic sound sources under power-constrained conditions as noted by Hao, Xie, and Ma [Proceedings of the 2019 Western China Acoustics Academic Conference, Guangzhou, China (November 5-9, 2019)]. This paper proposes a permanent magnet drive technology to enhance the electromechanical conversion efficiency of can-type electromagnetic transducers under low-power driving conditions. The can-type transducers consist of coils, an armature, and a cylindrical magnetic core with a central pillar, similar to the pot core proposed by Cui, Xu, Xu, and Shui [Electr.
View Article and Find Full Text PDFJ Acoust Soc Am
January 2025
National Key Laboratory of Underwater Acoustic Technology, Harbin Engineering University, Harbin 150001, China.
The flextensional transducer (FT) is a typical low-frequency transmitting transducer that is capable of high-power operation due to its capacity for displacement amplification. This article uses the structural configuration of the class IV FT as the basis for designing a ring transducer, which is a circular structure comprising a multitude of class IV flextensional structures as well as circular acoustic radiation structures. The flextensional structure drives the circular acoustic radiation structure, which in turn generates sound waves at low frequencies.
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