Underwater acoustic

The paper proposes an enhanced solution for improving the accuracy of underwater object positioning based on the Ultra-Short Baseline (USBL) sonar principle. In shallow water regions, complex hydrological phenomena affect the quality of underwater acoustic signal transmission and reception, making it essential to enhance the processing of these signal groups.

9p viambani 18-06-2024 2 1   Download

In this paper, we propose a method that uses the non-uniform Fast Fourier Transform (FFT) to compensate for Doppler frequency shifts in orthogonal frequency division multiplexing (OFDM) based underwater acoustic (UWA) communication systems. To estimate the Doppler frequency shift, the paper proposes using a pilot carrier frequency (PCF) that is identified by transmitting with greater power in the frequency domain compared to other subcarriers.

7p vijeff 30-11-2023 3 3   Download

An image transmission underwater communications system has been researched and developed during the past years due to its potential applications in life, military, oil exploitation, and transportation. In this brief report, a study on the effect of the modulation method on the image communication through the underwater acoustic channel was performed.

9p vifriedrich 06-09-2023 6 4   Download

Continued part 1, part 2 of ebook "Computing handbook: Computer science and software engineering" provides readers with contents including: natural language processing; understanding spoken language; neural networks; cognitive modeling; graphical models for probabilistic and causal reasoning; network organization and topologies; routing protocols; access control; data compression; localization in underwater acoustic sensor networks; semantic web; thread management for shared-memory multiprocessors;...

1154p hanlinhchi 29-08-2023 6 4   Download

This article proposes a multi-scale deep learning network to classify different underwater acoustic signal sources. The proposed network is cleverly designed with multiple branches, creating a multi-scale block which allows learning various spatial features of Constant-Q Transform spectrograms.

16p viargus 20-02-2023 3 2   Download

In this paper, we propose a reliable communication solution using space-time diversity technique but using only one transceiver antenna applied to mobile OFDM system in underwater communication environment. In our solution, instead of using multiple receive antennas, the transmitter transmits an OFDM signal N times consecutively.

9p vispyker 14-11-2022 10 4   Download

The simulation results showed that the proposed CAPL-MAC protocol achieved the earlier stated performance rather than by existing protocols such as Competitive Transmission-MAC and Channel Aware Aloha.

26p spiritedaway36 28-11-2021 8 1   Download

Anechoic layer is vital for the underwater acoustic stealth of submarines. This paper develops a simulation-based model for analysis of the acoustic properties of an underwater anechoic layer containing air-filled cavities. First, we present a numerical framework at a relevant scale to implement the acoustical model of an anechoic coating.

7p nguaconbaynhay12 13-06-2021 22 1   Download

This paper presents a simulation-based model for predicting the acoustic properties of underwater anechoic structures with its main layer made of viscoelastic sound absorbing materials including air-filled cavities. Some preliminary numerical results are first compared with the published analytical and experimental data to validate the proposed modeling.

12p cothumenhmong11 05-05-2021 16 1   Download

This paper investigates the impacts of InterChannel Interference (ICI) effects on a shallow underwater acoustic (UWA) orthogonal frequency-division multiplexing (OFDM) communication system. Considering both the turbulence of the water surface and the roughness of the bottom, a stochastic geometry-based channel model utilized for a wideband transmission scenario has been exploited to derive a simulation model. Since the system bandwidth and the subcarrier spacing is very limited in the range of a few kHz, the channel capacity of a UWA system is severely suffered by the ICI effect.

8p nguaconbaynhay11 16-04-2021 17 4   Download

In this paper, we propose a new decoder method at the receiver of system to compensate Doppler frequency shift for OFDM-based underwater acoustic communication systems. At the transmitter, in order to save bandwidth, we do not use additional signal header (preamble) in each OFDM frame as proposed in many conventional approaches.

6p vishizuka2711 07-04-2020 14 3   Download

Submarines are often covered with resonant sound absorbers known as anechoic coatings or tiles in order to avoid detection by sonar. A simulation-based model is developed for predicting the acoustic properties of underwater anechoic structures having matrix viscoelastic materials containing air-filled cavities.

6p viatani2711 14-02-2020 10 1   Download

This dissertation aims at developing accurate and efficient approaches of 8 designing shallow UWA channel simulators based on the measurement data of the real UWA channel in a specific shallow water environment.

128p cotithanh000 07-10-2019 9 2   Download

In this paper, we try to investigate what are differences between OFDMA and SC-FDMA in underwater acoustic (UWA) communication. OFDMA and SC-FDMA are well known by against multi-path interference capability and bandwidth efficiency using so both of them are also used in Downlink and Uplink in LTE.

9p vititan2711 13-08-2019 18 1   Download

To accomplish the sad duty of paying homage to Alain Glavieux, I have referred to his biography as much as my own memories. Two points of this biography struck me, although I had hardly paid attention to them until now. I first noted that Alain Glavieux, born in 1949, is the exact contemporary of information theory, since it was based on the articles of Shannon in 1948 and 1949. I also noted that his first research at the Ecole Nationale Supérieure de Télécommunications de Bretagne (ENST Brittany) related to underwater acoustic communications. ...

0p tiramisu0908 15-10-2012 51 3   Download

Bat and dolphin use sound to survive and have greatly superior capabilities to current technology with regard to resolution, object identification and material characterisation. Some bats can resolve some acoustic pulses thousands of times more efficiently than current technology (Thomas & Moss, 2004 ). Dolphins are capable of discriminating different materials based on acoustic energy, again significantly out-performing current detection systems.

142p qsczaxewd 22-09-2012 45 7   Download

The basic idea behind any sonar system is as follows: an acoustic signal (or ping) is emitted by the sonar into an area to be observed; the sonar then listens for echoes of the ping that have been produced when bouncing back from the objects that might be present in the area. Typically, sonar images are produced by plotting the intensity measured back by the sonar versus time, and since the speed of sound underwater is known (or can be measured), the time axis effectively corresponds to range from the sonar. In this way, just as light illuminates a scene...

252p lulanphuong 23-03-2012 89 15   Download

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Research Article Nonstationary System Analysis Methods for Underwater Acoustic Communications

14p sting05 09-02-2012 43 6   Download

SYSTEM OVERVIEW The Tsunami Warning System (TWS) designed by Envirtech is composed of the following main subsystems: · an Underwater Module (UM) to be installed at the sea bottom in open sea location for the accurate measurement of the tide and the identification of anomalous conditions. · a Surface Buoy (SB) moored close to the UM to receive via acoustic link the measurement of UM to be transferred via satellite link to a Data Centre (DC) for visualization and analysis.

14p khanhpro89 13-04-2011 83 12   Download

Estimating bearings of multiple narrowband signals from measurements collected by an array of sensors has been a very active research problem for the last two decades. Typical applications of this problem are radar, communication, and underwater acoustics. Many algorithms have been proposed to solve the bearing estimation

25p longmontran 18-01-2010 68 6   Download