Time reversed reverberation focusing in a waveguide

Lingevitch, Joseph F.; Song, H. C.; Kuperman, W. A.

doi:10.1121/1.1479148

Cited by 55 publications

(22 citation statements)

References 17 publications

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“…Studies on time-reversal in waveguides 10,11 suggested that when the dispersed waves resulting from a transducer being excited by a pulse are time-reversed and re-emitted, wave re-compression occurs at the source location, giving rise to a high amplitude pulse. However, the effect of dispersion on wave re-compression has not been addressed.…”

Section: Introductionmentioning

confidence: 99%

Computerized time-reversal method for structural health monitoring

2003

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In this paper an experimental and theoretical investigation of the applicability of the time-reversal concept to guided waves in plates, where the waves are dispersive and of multi-modes. It is shown that although temporal and spatial focusing can be achieved through time reversal, the dispersive behavior of the flexural waves renders it impossible to exactly reconstruct the waveform of the original excitation. Nevertheless, the temporal and spatial focusing allows the development of a synthetic time-reversal array method for a distributed network of sensors and actuators. This new method, which overcomes the limitation of the conventional phased array method that operates under pulse-echo mode, can considerably enhance the signal strength, thus reducing the number of sensors and actuators required to achieve a given signal-to-noise ratio.

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Section: Introductionmentioning

confidence: 99%

Computerized time-reversal method for structural health monitoring

2003

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“…9,10 This decomposition is also a means to separate the echo of a target from ground reverberation 11 and it was used to achieve reverberation focusing and nulling. 12,13 Recent at sea experiments confirm the efficiency of the DORT method for detection and focusing in a shallow water environment. 14,15 However, the aforementioned studies only considered isotropic scatterers.…”

Section: Introductionmentioning

confidence: 86%

Characterization of an elastic target in a shallow water waveguide by decomposition of the time-reversal operator

Philippe¹,

Prada²,

Rosny³

et al. 2008

The Journal of the Acoustical Society of America

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This paper reports the results of an investigation into extracting of the backscattered frequency signature of a target in a waveguide. Retrieving the target signature is difficult because it is blurred by waveguide reflections and modal interference. It is shown that the decomposition of the time-reversal operator method provides a solution to this problem. Using a modal theory, this paper shows that the first singular value associated with a target is proportional to the backscattering form function. It is linked to the waveguide geometry through a factor that weakly depends on frequency as long as the target is far from the boundaries. Using the same approach, the second singular value is shown to be proportional to the second derivative of the angular form function which is a relevant parameter for target identification. Within this framework the coupling between two targets is considered. Small scale experimental studies are performed in the 3.5 MHz frequency range for 3 mm spheres in a 28 mm deep and 570 mm long waveguide and confirm the theoretical results.

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“…6 The reverberation then can be treated as a single ͑extended͒ source problem in array processing. This suggests that a single snapshot would permit obtaining an estimate of the transfer function vector when a͒ there is a strong reverberation return, i.e., the high reverberation-to-noise and/or reverberation-to-echo case.…”

Section: Reverberation Nulling: Descriptionmentioning

confidence: 99%

“…5 The other approach to enhance active target detection is reverberation nulling recognizing that focusing and nulling are complementary. Lingevitch et al 6 recently have shown in simulation that backscattering from the rough water-bottom interface can serve as a surrogate probe source in time reversal. The concept is based on the fact that a time-gated portion of reverberation provides an estimate of the transfer function vector between a TRM array and the range cell along the bottom.…”

Section: Introductionmentioning

confidence: 99%

Experimental demonstration of adaptive reverberation nulling using time reversal

Song

Hodgkiss

Kuperman

et al. 2005

The Journal of the Acoustical Society of America

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The concept of environmentally adaptive reverberation nulling using a time reversal mirror ͑TRM͒ recently has been described ͓Song et al., J. Acoust. Soc. Am. 116, 762-768 ͑2004͔͒. In this paper, monostatic reverberation nulling is demonstrated experimentally at 850 and 3500 Hz using data from a shallow water experiment conducted off the west coast of Italy in April 2003. The active transmission of a seafloor spatial null from a vertical source array is shown to result in the attenuation by 3 -5 dB of prominent reverberation features with their levels being reduced to that of the more diffuse reverberation background.

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Time reversed reverberation focusing in a waveguide

Cited by 55 publications

References 17 publications

Computerized time-reversal method for structural health monitoring

Computerized time-reversal method for structural health monitoring

Characterization of an elastic target in a shallow water waveguide by decomposition of the time-reversal operator

Experimental demonstration of adaptive reverberation nulling using time reversal

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