Determine optimal bandwidth for modulation in underwater communication channel based on PSO

Author(s):  
Hai-Peng Ren ◽  
Yang Zhao ◽  
Jie Li
2018 ◽  
Vol 1 (1) ◽  
Author(s):  
Alexander Andonov ◽  
◽  
◽  

On the basis of the latest developments, an improved model of underwater communication channel is presented. A set of programs to allow calculation of the basic parameters of the channel over a wide range of parameters has been created. Mathematical models for calculating the spreading factor are developed. A process of creating the model is reviewed, so that the resulting model should become easily expandable. Userfriendly information-transfer interface is set between the programs and input and output data files.


2020 ◽  
Vol 7 (1) ◽  
pp. F39-F44
Author(s):  
T. O. Onur

Underwater communication has become a widely studied area in recent years and showed great potential to be an area of research. Acoustic communication is often preferred in underwater communication due to its suitability for an underwater diffusion environment. However, in underwater communication, the physical and chemical properties of the water environment affect sound propagation. Therefore, determining and examining parameters affecting channel performance in underwater communication plays an essential role in inefficient communication. In this study, the effects of salinity, depth, noise, temperature, and frequency parameters for the underwater channel model are examined. By determining the effects of these parameters on spherical and cylindrical propagation, suitable propagation geometry and parameter values for an efficient channel are investigated. In light of the results obtained, in case of studying in a limited area, the path and absorption losses can be reduced by selecting cylindrical propagation as a geometrical propagation model, thereby an efficient channel model can be formed. Keywords: cylindrical propagation, spherical propagation, underwater communication channel, acoustic communication, path loss, absorption loss.


Author(s):  
P. Unru

Гидроакустический канал связи отличается значительной и нестационарной многолучевостью, что делает разработку помехоустойчивой и высокоскоростной гидроакустической системы связи весьма нетривиальной задачей. В работе представлен авторский метод адаптации диаграмм направленности гидроакустических антенных решеток под текущие условия канала. Его новизна – в структуре пилот-сигнала, предназначенного для определения оптимального угла наклона передающей диаграммы направленности, и способе его приема и обработки. Приводятся результаты проведенных автором математического моделирования и экспериментальной оценки эффективности предлагаемого метода.


Author(s):  
D. Van Dyck

An (electron) microscope can be considered as a communication channel that transfers structural information between an object and an observer. In electron microscopy this information is carried by electrons. According to the theory of Shannon the maximal information rate (or capacity) of a communication channel is given by C = B log2 (1 + S/N) bits/sec., where B is the band width, and S and N the average signal power, respectively noise power at the output. We will now apply to study the information transfer in an electron microscope. For simplicity we will assume the object and the image to be onedimensional (the results can straightforwardly be generalized). An imaging device can be characterized by its transfer function, which describes the magnitude with which a spatial frequency g is transferred through the device, n is the noise. Usually, the resolution of the instrument ᑭ is defined from the cut-off 1/ᑭ beyond which no spadal information is transferred.


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