Time‐reversal focusing with less than a full water column source array

1997 ◽  
Vol 102 (5) ◽  
pp. 3171-3171 ◽  
Author(s):  
W. S. Hodgkiss ◽  
W. A. Kuperman ◽  
H. C. Song ◽  
T. Akal ◽  
C. Ferla ◽  
...  
Keyword(s):  
Water Column ◽  
Time Reversal ◽  
Source Array

Spatial resolution of time-reversal processing with a virtual source array

2017 ◽  
Vol 142 (4) ◽  
pp. 2731-2731
Author(s):  
Donghyeon Kim ◽  
Gihoon Byun ◽  
Jea Soo Kim
Keyword(s):  
Spatial Resolution ◽  
Time Reversal ◽  
Virtual Source ◽  
Source Array

Multiple time-reversal focusing with a virtual source array

2018 ◽  
Vol 143 (3) ◽  
pp. 1789-1789
Author(s):  
Gihoon Byun ◽  
H. C. Song ◽  
J. S. Kim
Keyword(s):  
Time Reversal ◽  
Multiple Time ◽  
Virtual Source ◽  
Source Array

scholarly journals Virtual Source Array-Based Multiple Time-Reversal Focusing

2018 ◽  
Vol 8 (1) ◽  
pp. 99 ◽  
Author(s):  
Gihoon Byun ◽  
Heechun Song ◽  
Jeasoo Kim
Keyword(s):  
Time Reversal ◽  
Multiple Time ◽  
Virtual Source ◽  
Source Array

scholarly journals Effects of Water Column Variations on Sound Propagation and Underwater Acoustic Communications

Sensors ◽  
2019 ◽  
Vol 19 (9) ◽  
pp. 2105
Author(s):  
Salman I. Siddiqui ◽  
Hefeng Dong
Keyword(s):  
Water Column ◽  
Impulse Response ◽  
Time Reversal ◽  
Sound Propagation ◽  
Channel Impulse Response ◽  
Underwater Acoustic Communications ◽  
Underwater Sound ◽  
Acoustic Communications ◽  
Underwater Acoustic ◽  
Environmental Variations

Underwater sound propagation is very sensitive to geometric and environmental variations. The geometric variations are the motion of the source and/or receiver, while the environmental variations are due to surface motion and water column variations. In order to reduce the effects of these variations, it is necessary to understand their effects on sound propagation. In this paper, some water column variations are reported, and their effect on the underwater sound propagation is studied. These water column variations were observed during an experiment in the TrondheimFjord on 22 September 2016. Strong amplitude variations were observed in the channel impulse response during the experiment. The Doppler analysis was performed on the channel impulse response, which showed strong Doppler variations. The amplitude and Doppler variations suggested the presence of water column variations. To demonstrate the performance of the communication system, the time reversal combiner was implemented. The system performance was demonstrated by computing the mean squared error between the transmitted signal and the output of the combiner. The performance of the combiner degraded by ~2.5 dB in the presence of water column variations. Due to these variations, the amplitudes of the arrivals changed rapidly, which posed a great challenge for the time reversal combiner. These amplitude variations affected the focusing of the combiner and hence induced intersymbol interference and performance degradation. This work provides an insight into the effects of water column variations on underwater sound propagation and underwater acoustic communications.

ACOUSTIC TIME SERIES VARIABILITY AND TIME REVERSAL MIRROR DEFOCUSING DUE TO CUMULATIVE EFFECTS OF WATER COLUMN VARIABILITY

2001 ◽  
Vol 09 (04) ◽  
pp. 1455-1474 ◽  
Author(s):  
KEVIN D. LePAGE
Keyword(s):  
Time Series ◽  
Water Column ◽  
Time Reversal ◽  
Signal Intensity ◽  
Sound Speed ◽  
Narrow Band ◽  
Cumulative Effects ◽  
Time Reversal Mirror ◽  
Speed Fluctuations ◽  
Focus Intensity

The variability of the arrival structure of narrow band waveforms is derived for adiabatic propagation in a fluctuating ocean channel. Expressions for the expected value of the signal intensity are obtained for sound speed fluctuations characterized in a second moment sense over range, depth and time. Similar expressions are obtained for the focus intensity of a time reversal mirror.

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