Broadband Ultrasonic Target Strengths of Hollow Ceramic Flotation Spheres

Atkins, P.R.; Francis, David T. I.; Foote, Kenneth G.

doi:10.1109/oceanse.2007.4302487

Cited by 8 publications

(3 citation statements)

References 20 publications

(13 reference statements)

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“…Minimization yielded a shear wave value, C T = 6350 m/s, considerable lower than the nominal, C T = 6512 m/s. The resulting optimal shell thickness value was 1.346 mm, above the given 1.3 mm, although the thickness has been found to be inhomogeneous [36]. Oscillations seen in Fig.…”

Section: Ceramic Air-filled Shellsmentioning

confidence: 88%

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Broadband amplitude and phase sonar calibration using LFM pulses for high-resolution study of hard and soft acoustic targets

Islas-Cital

Atkins

Foo

et al. 2011

OCEANS 2011 IEEE - Spain

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Target phase has been advanced as an additional parameter for sonar target identification. Previous studies aiming to classify fish and other marine organisms by means of the phase angle component in their echoes have reported promising results. Similarly, the use of broadband techniques to simultaneously obtain spectral information and achieve good spatial resolution has been deemed advantageous. Therefore, broadband active sonar that utilizes both amplitude and phase would appear to be a desirable system. Adopting this approach requires suitable calibration methods that account for complex sensitivity over large bandwidths. Current calibration procedures that incorporate pulse compression with linear-frequency modulated (LFM) pulses are available but do not address phase. The present work expands on these methods in order to achieve broadband sonar amplitude and phase calibration, using spectral processing of LFM pulses and standard targets. Target phase is obtained as the difference of phase angles at two frequencies, in order to remove range effects. This paper presents time-domain scattering, together with calibrated target strength (TS) and phase spectra of solid tungsten carbide spheres and air-filled ceramic shells, obtained in a laboratory water tank. Experimental results are compared to theoretical models to validate measurements and identify underlying echo formation mechanisms.

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Section: Ceramic Air-filled Shellsmentioning

confidence: 88%

“…The acoustic properties of thin elastic shells have been evaluated with backscattering measurements in the past [36]. Broadband target strength (TS) measurements obtained with LFM pulses are presented in Fig.…”

Section: Ceramic Air-filled Shellsmentioning

confidence: 99%

Broadband amplitude and phase sonar calibration using LFM pulses for high-resolution study of hard and soft acoustic targets

Islas-Cital

Atkins

Foo

et al. 2011

OCEANS 2011 IEEE - Spain

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show abstract

“…The encouraging evidence from the present study highlights the flexibility of the standard-target method, as adapted to the calibration of phase, with a precision that is primarily constrained by the knowledge of the material parameters of the reference target, sensitivity to mechanical resonances, and signal-to-noise ratio. Other topics of interest would be the use of different reference targets, such as airfilled shells, 49 and the possibility of adapting this phase calibration method to the time domain, especially to systems relying on short broadband pulses. 31,35 …”

Section: Discussionmentioning

confidence: 99%

Phase calibration of sonar systems using standard targets and dual-frequency transmission pulses

Islas-Cital

Atkins

Foo

et al. 2011

The Journal of the Acoustical Society of America

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The phase angle component of the complex frequency response of a sonar system operating near transducer resonance is usually distorted. Interpretation and classification of the received sonar signal benefits from the preservation of waveform fidelity over the full bandwidth. A calibration process that measures the phase response in addition to the amplitude response is thus required. This paper describes an extension to the standard-target calibration method to include phase angle, without affecting the experimental apparatus, by using dual-frequency transmission pulses and frequency-domain data processing. This approach reduces the impact of unknown range and sound speed parameters upon phase calibration accuracy, as target phase is determined from the relationship of the two frequency components instead of relying on a local phase reference. Tungsten carbide spheres of various sizes were used to simultaneously calibrate the amplitude and phase response of an active sonar system in a laboratory tank. Experimental measurements of target phase spectra are in good agreement with values predicted from a theoretical model based upon full-wave analysis, over an operating frequency of 50-125 kHz.

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Robustness of target strength of an immersed, hollow ceramic flotation sphere of constant shell thickness

Francis¹,

Foote²

2007

Oceans 2007

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Broadband Ultrasonic Target Strengths of Hollow Ceramic Flotation Spheres

Cited by 8 publications

References 20 publications

Broadband amplitude and phase sonar calibration using LFM pulses for high-resolution study of hard and soft acoustic targets

Broadband amplitude and phase sonar calibration using LFM pulses for high-resolution study of hard and soft acoustic targets

Phase calibration of sonar systems using standard targets and dual-frequency transmission pulses

Robustness of target strength of an immersed, hollow ceramic flotation sphere of constant shell thickness

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