Source level measurements of a cavitation noise source in a water tunnel using a time reversal mirror

2004 ◽  
Vol 116 (4) ◽  
pp. 2575-2575
Author(s):  
Christopher Barber ◽  
Gerald C. Lauchle
Keyword(s):  
Time Reversal ◽  
Noise Source ◽  
Water Tunnel ◽  
Cavitation Noise ◽  
Source Level ◽  
Time Reversal Mirror

Water Tunnel Acoustic Measurements Using a Time Reversal Mirror

2001 ◽  
Author(s):  
Christopher Barber ◽  
Gerald C. Lauchle ◽  
Dean E. Capone
Keyword(s):  
Time Reversal ◽  
Measurement Techniques ◽  
Processing System ◽  
Acoustic Energy ◽  
Water Tunnel ◽  
Water Tank ◽  
State University ◽  
Acoustic Measurements ◽  
Time Reversal Mirror ◽  
Data Acquisition And Processing

Abstract Acoustic time reversal is a process in which acoustic energy received at an array is recorded, time-reversed, and then rebroadcast through the same or a collocated array. The result is that the original signal is “retrofocused” in time and space to the original source location without regard to the propagation paths or characteristics of the complex media between source and receiver. The array used for receive and rebroadcast, together with the data acquisition and processing system, is referred to as a time reversal mirror (TRM). Adaptation of time reversal mirrors to the problem of water tunnel acoustic measurements is examined. A concept demonstration test is planned for the Garfield Thomas Water Tunnel (GTWT) at the Pennsylvania State University Applied Research Laboratory, with the objective of demonstrating improved acoustic measurement capabilities compared to other conventional measurement techniques. An outline of the planned test is presented, as well as results from preliminary water tank testing of the arrays and instrumentation to be used in the GTWT experiment. A mathematical description of the time reversal mirror is developed, and preliminary conclusions regarding expected TRM performance in the water tunnel environment and limitations of the proposed measurement scheme are discussed.

scholarly journals M-ary nonlinear sine chirp spread spectrum for underwater acoustic communication based on virtual time-reversal mirror method

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Songzuo Liu ◽  
Habib Hussain Zuberi ◽  
Yi Lou ◽  
Muhmmad Bilal Farooq ◽  
Shahabuddin Shaikh ◽  
...  
Keyword(s):  
Acoustic Communication ◽  
Time Reversal ◽  
Spread Spectrum ◽  
Underwater Acoustic Communication ◽  
Half Cycle ◽  
Spreading Factor ◽  
Underwater Acoustic ◽  
Virtual Time ◽  
Chirp Spread Spectrum ◽  
Time Reversal Mirror

AbstractLinear chirp spread spectrum technique is widely used in underwater acoustic communication because of their resilience to high multipath and Doppler shift. Linear frequency modulated signal requires a high spreading factor to nearly reach orthogonality between two pairs of signals. On the other hand, nonlinear chirp spread spectrum signals can provide orthogonality at a low spreading factor. As a result, it improves spectral efficiency and is more insensitive to Doppler spread than the linear counterpart. To achieve a higher data rate, we propose two variants (half cycle sine and full cycle sine) of the M-ary nonlinear sine chirp spread spectrum technique based on virtual time-reversal mirror (VTRM). The proposed scheme uses different frequency bands to transmit chirp, and VTRM is used to improve the bit error rate due to high multipath. Its superior Doppler sensitivity makes it suitable for underwater acoustic communication. Furthermore, the proposed method uses a simple, low-power bank of matched filters; thus, it reduces the overall system complexity. Simulations are performed in different underwater acoustic channels to verify the robustness of the proposed scheme.

scholarly journals Estimation of the Noise Source Level of a Commercial Ship Using On-Board Pressure Sensors

2021 ◽  
Vol 11 (3) ◽  
pp. 1243
Author(s):  
Hongseok Jeong ◽  
Jeung-Hoon Lee ◽  
Yong-Hyun Kim ◽  
Hanshin Seol
Keyword(s):  
Noise Source ◽  
Pressure Sensors ◽  
Low Frequency ◽  
Frequency Resolution ◽  
Source Strength ◽  
Recording Time ◽  
Source Level ◽  
The One ◽  
Hydrophone Array ◽  
Good Agreement

The dominant underwater noise source of a ship is known to be propeller cavitation. Recently, attempts have been made to quantify the source strength using on-board pressure sensors near the propeller, as this has advantages over conventional noise measurement. In this study, a beamforming method was used to estimate the source strength of a cavitating propeller. The method was validated against a model-scale measurement in a cavitation tunnel, which showed good agreement between the measured and estimated source levels. The method was also applied to a full-scale measurement, in which the source level was measured using an external hydrophone array. The estimated source level using the hull pressure sensors showed good agreement with the measured one above 400 Hz, which shows potential for noise monitoring using on-board sensors. A parametric study was carried out to check the practicality of the method. From the results, it was shown that a sufficient recording time is required to obtain a consistent level at high frequencies. Changing the frequency resolution had little effect on the result, as long as enough data were provided for the one-third octave band conversion. The number of sensors affected the mid- to low-frequency data.

Demonstration of a high-frequency acoustic barrier with a time-reversal mirror

2003 ◽  
Vol 28 (2) ◽  
pp. 246-249 ◽  
Author(s):  
H. Song ◽  
W.A. Kuperman ◽  
W.S. Hodgkiss ◽  
T. Akal ◽  
P. Guerrini
Keyword(s):  
Time Reversal ◽  
High Frequency ◽  
Time Reversal Mirror

Environmentally adaptive reverberation nulling using a time reversal mirror

2004 ◽  
Vol 116 (2) ◽  
pp. 762-768 ◽  
Author(s):  
H. C. Song ◽  
S. Kim ◽  
W. S. Hodgkiss ◽  
W. A. Kuperman
Keyword(s):  
Time Reversal ◽  
Time Reversal Mirror

scholarly journals An Underwater Time Reversal Communication Method Using Symbol-Based Doppler Compensation with a Single Sound Pressure Sensor

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3279
Author(s):  
Anbang Zhao ◽  
Caigao Zeng ◽  
Juan Hui ◽  
Lin Ma ◽  
Xuejie Bi
Keyword(s):  
Time Reversal ◽  
Multipath Propagation ◽  
Single Element ◽  
Communication Performance ◽  
Songhua River ◽  
Communication Method ◽  
Doppler Effects ◽  
Communication Experiment ◽  
Time Reversal Mirror ◽  
Doppler Compensation

Due to the significant multipath and Doppler effects in the underwater acoustic (UWA) channel, the quality of the received signal is degraded, which seriously affects the performance of UWA communication. The paper proposes a time reversal UWA communication method combined with a symbol-based Doppler compensation (SBDC) technique to solve those problems. A single element time reversal mirror (TRM) is used to realize channel equalization and mitigate the inter-symbol interference (ISI) resulting from multipath propagation. The SBDC technique is subsequently used to compensate Doppler effects in the received signal, thereby reducing the bit error rate (BER) and improving the communication performance. In order to verify the performance of the proposed communication method, some simulations with real sounding channels were performed. Moreover, a field UWA communication experiment was conducted in the Songhua River (Harbin, China). The UWA communication experiment achieves nearly error-free performance with a communication rate of 100 bit/s in the bandwidth of 2 kHz. The results of the experiment demonstrate the feasibility and robustness of the proposed UWA communication method.

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