A digital correlative accumulation and its application to underwater acoustic telemetry, telecontrol and remote sensing

1984 ◽  
Vol 2 (2) ◽  
pp. 168-176 ◽  
Author(s):  
Xu Tianzeng
Keyword(s):  
Remote Sensing ◽  
Acoustic Telemetry ◽  
Underwater Acoustic

scholarly journals The Effect of Attenuation from Fish Shoals on Long-Range, Wide-Area Acoustic Sensing in the Ocean

2019 ◽  
Vol 11 (21) ◽  
pp. 2464 ◽  
Author(s):  
Daniel Duane ◽  
Byunggu Cho ◽  
Ankita D. Jain ◽  
Olav Rune Godø ◽  
Nicholas C. Makris
Keyword(s):  
Remote Sensing ◽  
Long Range ◽  
Cross Sections ◽  
Electromagnetic Waves ◽  
Low Frequency ◽  
Wide Area ◽  
Line Transect ◽  
Acoustic Sensing ◽  
Underwater Acoustic ◽  
Primary Means

Acoustics is the primary means of long-range and wide-area sensing in the ocean due to the severe attenuation of electromagnetic waves in seawater. While it is known that densely packed fish groups can attenuate acoustic signals during long-range propagation in an ocean waveguide, previous experimental demonstrations have been restricted to single line transect measurements of either transmission or backscatter and have not directly investigated wide-area sensing and communication issues. Here we experimentally show with wide-area sensing over 360° in the horizontal and ranges spanning many tens of kilometers that a single large fish shoal can significantly occlude acoustic sensing over entire sectors spanning more than 30° with corresponding decreases in detection ranges by roughly an order of magnitude. Such blockages can comprise significant impediments to underwater acoustic remote sensing and surveillance of underwater vehicles, marine life and geophysical phenomena as well as underwater communication. This makes it important to understand the relevant mechanisms and accurately predict attenuation from fish in long-range underwater acoustic sensing and communication. To do so, we apply an analytical theory derived from first principles for acoustic propagation and scattering through inhomogeneities in an ocean waveguide to model propagation through fish shoals. In previous experiments, either the attenuation from fish in the shoal or the scattering cross sections of fish in the shoal were measured but not both, making it impossible to directly confirm a theoretical prediction on attenuation through the shoal. Here, both measurements have been made and they experimentally confirm the waveguide theory presented. We find experimentally and theoretically that attenuation can be significant when the sensing frequency is near the resonance frequency of the shoaling fish. Negligible attenuation was observed in previous low-frequency ocean acoustic waveguide remote sensing (OAWRS) experiments because the sensing frequency was sufficiently far from the swimbladder resonance peak of the shoaling fish or the packing densities of the fish shoals were not sufficiently high. We show that common heuristic approaches that employ free space scattering assumptions for attenuation from fish groups can lead to significant errors for applications involving long-range waveguide propagation and scattering.

scholarly journals Laser‐induced underwater acoustic source for remote sensing of sea floor

1994 ◽  
Vol 95 (5) ◽  
pp. 3021-3021 ◽  
Author(s):  
S. V. Egerev ◽  
A. N. Ivakin ◽  
O. B. Ovchinnikov ◽  
A. E. Pashin
Keyword(s):  
Remote Sensing ◽  
Acoustic Source ◽  
Underwater Acoustic ◽  
Sea Floor

The state of the art in underwater acoustic telemetry

2000 ◽  
Vol 25 (1) ◽  
pp. 4-27 ◽  
Author(s):  
D.B. Kilfoyle ◽  
A.B. Baggeroer
Keyword(s):  
Acoustic Telemetry ◽  
State Of The Art ◽  
The State ◽  
Underwater Acoustic

scholarly journals An Underwater Acoustic Telemetry Modem for Eco-Sensing

2006 ◽  
Author(s):  
R.A. Iltis ◽  
R. Kastner ◽  
Hua Lee ◽  
D. Doonan ◽  
Tricia Fu ◽  
...  
Keyword(s):  
Acoustic Telemetry ◽  
Underwater Acoustic

scholarly journals Understanding summertime thermal refuge use by adult Atlantic salmon using remote sensing, river temperature monitoring, and acoustic telemetry

2018 ◽  
Vol 75 (11) ◽  
pp. 1999-2010 ◽  
Author(s):  
Danielle M. Frechette ◽  
Stephen J. Dugdale ◽  
Julian J. Dodson ◽  
Normand E. Bergeron
Keyword(s):  
Remote Sensing ◽  
Atlantic Salmon ◽  
High Temperatures ◽  
Acoustic Telemetry ◽  
Temperature Tolerance ◽  
Temperature Monitoring ◽  
Behavioral Thermoregulation ◽  
Thermal Infrared Remote Sensing ◽  
River Temperature ◽  
Thermal Refuge

Adult Atlantic salmon (Salmo salar) return to natal rivers several months before spawning and during summer can be subjected to temperatures that exceed their upper temperature tolerance limits. Salmon use thermal refuges to minimize exposure to high temperatures, but little information exists regarding behavioral thermoregulation by adult Atlantic salmon. We examined behavioral thermoregulation by Atlantic salmon during summer in-river residence in a Quebec river with a novel combination of thermal infrared remote sensing, river temperature monitoring, and acoustic telemetry. Adults engaged in behavioural thermoregulation at cooler ambient river temperatures (17–19 °C) than previously recorded for this species and maintained body temperature within a narrow range (16–20 °C) via use of cool and warm refuges. Adults used large, stable, stratified pools as refuges, allowing multiple individuals to thermoregulate simultaneously without leaving the pool. Low river discharge and high temperatures can be physical barriers to salmon migration, preventing them from accessing suitable refuges (e.g., pools). Identifying and maintaining connectivity to thermal refuges may be critical for persistence of Atlantic salmon populations as climate changes and rivers warm.

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