Free‐field acoustic calibration of long underwater acoustic arrays in a closed chamber

1991 ◽  
Vol 90 (5) ◽  
pp. 2652-2657 ◽  
Author(s):  
L. D. Luker ◽  
J. F. Zalesak
Keyword(s):  
Free Field ◽  
Closed Chamber ◽  
Underwater Acoustic ◽  
Acoustic Arrays ◽  
Acoustic Calibration

scholarly journals Calibration standards for hydrophones and autonomous underwater noise recorders for frequencies below 1 kHz: current activities of EMPIR “UNAC-LOW” project

ACTA IMEKO ◽  
2018 ◽  
Vol 7 (2) ◽  
pp. 32
Author(s):  
Alper Biber ◽  
Ata Can Korakci ◽  
Alexander Golick ◽  
Stephen Robinson ◽  
Gary Hayman ◽  
...  
Keyword(s):  
Free Field ◽  
Open Water ◽  
The European Union ◽  
Underwater Sound ◽  
Field Methods ◽  
Closed Chamber ◽  
Calibration Standards ◽  
Underwater Acoustic ◽  
Term Operation ◽  
Standing Wave Tube

The project entitled “UNderwater Acoustic Calibration standards for frequencies beLOW 1 kHz” (“UNAC-LOW”), currently active within the European Metrology Programme for Innovation and Research (EMPIR), is presented by describing its objectives and current activities. The project aims at developing the metrological capacity of the European Union (EU) for the calibration of hydrophones and autonomous recording systems for the frequency range between 20 Hz and 1 kHz, for which traceability is presently not fully available. In this way, EU metrological capacities for absolute measurement of underwater sound will be improved, with a direct effect on the implementation of regulation and EU Directives that require underwater acoustic measurements to be traceable. After having completed the initial project tasks regarding the review of existing methods and the design of the experimental setups, comparison measurements between the project partners are currently under way and their results will be validated and presented upon project end after first quarter of 2019. To ensure long-term operation of the calibration capabilities by each partner, a coherent EU metrology strategy for underwater acoustics will be developed as one of the main project outcomes. Current activities include the implementation of the calibration setups developed in earlier stages of the project for both hydrophones and autonomous recorders. The methods that shall be used for hydrophones are the pressure method in a closed chamber and the standing wave tube method. For autonomous recorders, in addition to the above methods, calibrations will be performed using free-field methods in different open-water test sites possessing suitable characteristics for low frequency measurements.

Detection and tracking of land vehicle activity by offshore underwater acoustic arrays

1997 ◽  
Vol 102 (5) ◽  
pp. 3193-3193
Author(s):  
Gerald L. D’Spain ◽  
Lewis P. Berger ◽  
William S. Hodgkiss ◽  
William A. Kuperman ◽  
LeRoy M. Dorman ◽  
...  
Keyword(s):  
Underwater Acoustic ◽  
Land Vehicle ◽  
Detection And Tracking ◽  
Acoustic Arrays ◽  
Vehicle Activity

scholarly journals The Reflection Coefficients Measurement Method for the Underwater Acoustic Materials Based on the Single Vector Hydrophone

2019 ◽  
Vol 37 (5) ◽  
pp. 1036-1043
Author(s):  
Shengguo Shi ◽  
Chao Wang ◽  
Bo Hu
Keyword(s):  
Measurement Method ◽  
Free Field ◽  
Pulse Signal ◽  
Measuring Method ◽  
High Ratio ◽  
Reflection Coefficients ◽  
Inverse Filtering ◽  
Post Processing ◽  
Underwater Acoustic ◽  
Vector Hydrophone

In order to obtain the normal acoustic reflection coefficients of underwater acoustic materials in the free field with the wideband pulse signal, a new measuring method with a single vector hydrophone and the post-processing inverse filtering is put forward. Numerical simulations had been conducted to comparatively analyze the measurement performances of the measuring method. The simulation results show that the present method should be established on the high ratio of signal to the noise and it is not sensitive to the system error. The experiment result shows that the post-processing inverse filtering measuring method is more effective comparing with the method without the post-processing inverse filtering, especially the measurement consequence of the post-processing inverse filtering measurement method tends to the theoretical value when the frequency is higher than 2.5 kHz, because limitation of the transducer.

Method for measuring the characteristics of underwater acoustic arrays in real environments

1994 ◽  
Vol 37 (1) ◽  
pp. 70-75
Author(s):  
S. V. Burenkov ◽  
N. I. Knyazeva ◽  
S. S. Naumov ◽  
E. A. Zenyutich
Keyword(s):  
Underwater Acoustic ◽  
Acoustic Arrays
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