Measurements and modeling comparisons of underwater communications performance at three shallow-water sites

2003 ◽  
Author(s):  
M. Siderius ◽  
M.B. Porter ◽  
P. Hursky ◽  
V.K. McDonald
Keyword(s):  
Shallow Water ◽  
Underwater Communications

A Parametric Study of Sound Focusing in Shallow Water by Using Acoustic Contrast Control

2014 ◽  
Vol 22 (04) ◽  
pp. 1450012 ◽  
Author(s):  
Yi-Wei Lin ◽  
Gee-Pinn James Too
Keyword(s):  
Shallow Water ◽  
Frequency Control ◽  
Control Process ◽  
Environmental Parameters ◽  
Specific Area ◽  
Underwater Communications ◽  
Control Zone ◽  
Sound Energy ◽  
Shift Keying ◽  
And Control

Acoustic contrast control is a sound focusing technique applied to personal audio system devices to provide the optimal sound contrast for increasing or decreasing the potential sound energy of a specific area. In this study, acoustic contrast control was developed for sound focusing in shallow water. The advantage of this technique is the establishment of two zones: a bright zone around the user and a dark zone for other regions. In the acoustic contrast control process, computational ocean acoustics are used to calculate the Green's function between the source point and the field point. The effects of environmental parameters, which comprised the number of control sources, transmission frequency, control distances between sources and control zone of a geometric location were simulated. The results show that acoustic contrast control is an effective approach for sound focusing in shallow water that can increase the potential sound energy of a specific area. Employing this technique can also enhance underwater communications by using frequency-shift keying modulation for cross-talking applications.

An Arctic-Type Shallow-Water Acoustic Waveguide as an Information Transmission Channel for Underwater Communications

2018 ◽  
Vol 64 (6) ◽  
pp. 692-697 ◽  
Author(s):  
M. V. Volkov ◽  
V. A. Grigor’ev ◽  
I. V. Zhilin ◽  
A. A. Lunkov ◽  
V. G. Petnikov ◽  
...  
Keyword(s):  
Information Transmission ◽  
Shallow Water ◽  
Transmission Channel ◽  
Underwater Communications ◽  
Acoustic Waveguide

Spatial assemblage structure of shallow-water reef fish in Southwest Australia

2020 ◽  
Vol 649 ◽  
pp. 125-140
Author(s):  
DS Goldsworthy ◽  
BJ Saunders ◽  
JRC Parker ◽  
ES Harvey
Keyword(s):  
Shallow Water ◽  
Reef Fish ◽  
Marine Environment ◽  
Fish Assemblages ◽  
Canopy Cover ◽  
Reef Fishes ◽  
Reef Fish Assemblage ◽  
Reef Type ◽  
Present Distribution ◽  
Southwest Australia

Bioregional categorisation of the Australian marine environment is essential to conserve and manage entire ecosystems, including the biota and associated habitats. It is important that these regions are optimally positioned to effectively plan for the protection of distinct assemblages. Recent climatic variation and changes to the marine environment in Southwest Australia (SWA) have resulted in shifts in species ranges and changes to the composition of marine assemblages. The goal of this study was to determine if the current bioregionalisation of SWA accurately represents the present distribution of shallow-water reef fishes across 2000 km of its subtropical and temperate coastline. Data was collected in 2015 using diver-operated underwater stereo-video surveys from 7 regions between Port Gregory (north of Geraldton) to the east of Esperance. This study indicated that (1) the shallow-water reef fish of SWA formed 4 distinct assemblages along the coast: one Midwestern, one Central and 2 Southern Assemblages; (2) differences between these fish assemblages were primarily driven by sea surface temperature, Ecklonia radiata cover, non-E. radiata (canopy) cover, understorey algae cover, reef type and reef height; and (3) each of the 4 assemblages were characterised by a high number of short-range Australian and Western Australian endemic species. The findings from this study suggest that 4, rather than the existing 3 bioregions would more effectively capture the shallow-water reef fish assemblage patterns, with boundaries having shifted southwards likely associated with ocean warming.

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