Signal-modelling methods applied to the free-field calibration of hydrophones and projectors in laboratory test tanks

Robinson, Stephen; Hayman, Gary; Harris, P M; Beamiss, G A

doi:10.1088/1361-6501/aac752

Cited by 16 publications

(6 citation statements)

References 32 publications

(55 reference statements)

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“…The tank experiment conducted to demonstrate the feasibility of this approach is described in Sec. 3. In section 4, it is shown, using the experimental data, that the same set of equivalent sources can reproduce the field of a single monopole both in free space and in a tank.…”

Section: Introductionmentioning

confidence: 99%

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On the use of the equivalent source method for free-field calibration of an acoustic radiator in a reverberant tank

Virovlyansky

Deryabin

2019

Journal of Sound and Vibration

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It is shown that the use of the equivalent source method allows one to reconstruct the sound field excited by an acoustic radiator in free space from the measurements of the sound filed excited by this radiator in a tank with reflecting boundaries. The key assumption underlying the proposed approach is that the same set of monopoles with the same strengths can reproduce the field of the radiator both in free space and in the tank. The monopole strengths are reconstructed from the measurements in the tank, and the field in free space is then calculated using the known Green function. The feasibility of the approach is demonstrated in a tank experiment.

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Section: Introductionmentioning

confidence: 99%

“…However, both methods are applicable only at sufficiently high frequencies. There exist more sophisticated methods which can be used at acoustic frequencies below the limits imposed by the echo-free time of the test tank [3,4].…”

Section: Introductionmentioning

confidence: 99%

On the use of the equivalent source method for free-field calibration of an acoustic radiator in a reverberant tank

Virovlyansky

Deryabin

2019

Journal of Sound and Vibration

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“…In order to calculate the unknown model signal parameters in this method, a linear or a non-linear fitting algorithm is required for a simple (without transients) or an extended (with transients) signal model, respectively. For the latter one, a good starting estimate for model parameters such as resonance frequencies and damping factors is needed for successful application [12].…”

Section: Introductionmentioning

confidence: 99%

Application of 2E-2U method for free-field underwater calibrations of hydrophones and projectors in a reverberant laboratory test tank

Çorakçı,

Biber,

Saydam

et al. 2024

Meas. Sci. Technol.

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In this paper, application of a Two-Equations Two-Unknowns (2E-2U) method is described for calibration of hydrophones and projectors below 1 kHz in a laboratory test tank. At low frequencies, amplitude and phase measurements for the calibration of the hydrophones and projectors in the test tank are diffucult to perform since echo-free time of the laboratory test tank is not large enough due to transducer initial transients and tank wall boundary reflections. To overcome these diffuculties, the 2E-2U method is applied to received (windowed) signals obtained during calibration measurements. Thus, the calibration measurements become possible at a frequency down to 250 Hz. These measurements in the test tank are performed for a hydrophone and a developed flextensional projector. First, the receive sensitivities for the hydrophone are calculated and validated by comparisons with pressure calibration in a closed chamber. Good agreements are obtained between two measurement platforms, with a maximum difference of 0.5 dB and uncertainty of 1.3 dB. Then, transmitting voltage response (TVR) of the flextensional projector is calculated and compared with the calibration data obtained from the method defined in the relevant standards. Good agreements are obtained between two TVR data with a maximum difference of 1.1 dB and uncertainty of 1.7 dB.

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“…Blake and Maga [5] were the first to demonstrate through experiments that a nonanechoic water tank satisfies the diffuse-field conditions in the frequency band above the Schroeder cutoff frequency; they also demonstrated that the diffusion field theory commonly used in a reverberation chamber in air is also applicable to a non-anechoic water tank. On the basis of their research work, after decades of development, non-anechoic tanks have been widely used in many fields, including the calibration of underwater transducers, [6][7][8] measurement of the acoustic parameters of underwater acoustic materials, [9,10] and measurement of the sound power radiated from complex structures. [11][12][13][14] The premise of using diffuse-field measurement methods in a non-anechoic water tank is that the modal density in the tank will be sufficiently high that the measurement of the reverberation time will have very good consistency.…”

Section: Introductionmentioning

confidence: 99%

Method for measuring the low-frequency sound power from a complex sound source based on sound-field correction in a non-anechoic tank

Tang

et al. 2023

Chinese Phys. B

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Similar to air reverberation chambers, non-anechoic water tanks are important acoustic measurement devices that can be used to measure the sound power radiated from complex underwater sound sources using diffusion field theory. However, the problem of the poor applicability of low-frequency measurements in these tanks has not yet been solved. Therefore, we propose a low-frequency acoustic measurement method based on sound-field correction (SFC) in an enclosed space that effectively solves the problem of measuring the sound power from complex sound sources below the Schroeder cut-off frequency in a non-anechoic tank. Using normal mode theory, the transfer relationship between the mean-square sound pressure in an underwater enclosed space and the free-field sound power of the sound source is established, and this is regarded as a correction term for the sound field between this enclosed space and the free field. This correction term can be obtained based on previous measurements of a known sound source. This term can then be used to correct the mean-square sound pressure excited by any sound source to be tested in this enclosed space and equivalently obtain its free-field sound power. Experiments were carried out in a non-anechoic water tank (9.0 m × 3.1 m × 1.7 m) to confirm the validity of the SFC method. Through measurements with a spherical sound source (whose free-field radiation characteristics are known), the correction term of the sound field between this water tank and the free field was obtained. On this basis, the sound power radiated from a cylindrical shell model under the action of mechanical excitation was measured. The measurement results were found to have a maximum deviation of 2.9 dB from the free-field results. These results show that the SFC method has good applicability in the frequency band above the first-order resonant frequency in a non-anechoic tank. This greatly expands the potential low-frequency applications of non-anechoic tanks.

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Signal-modelling methods applied to the free-field calibration of hydrophones and projectors in laboratory test tanks

Abstract: PAPER • OPEN ACCESSSignal-modelling methods applied to the free-field calibration of hydrophones and projectors in laboratory test tanks

Cited by 16 publications

References 32 publications

On the use of the equivalent source method for free-field calibration of an acoustic radiator in a reverberant tank

On the use of the equivalent source method for free-field calibration of an acoustic radiator in a reverberant tank

Application of 2E-2U method for free-field underwater calibrations of hydrophones and projectors in a reverberant laboratory test tank

Method for measuring the low-frequency sound power from a complex sound source based on sound-field correction in a non-anechoic tank

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