Demonstration at sea of the decomposition-of-the-time-reversal-operator technique

Gaumond, Charles F.; Fromm, David M.; Lingevitch, Joseph F.; Menis, Richard; Edelmann, Geoffrey F.; Calvo, David; Kim, Elisabeth

doi:10.1121/1.2150152

Cited by 21 publications

(10 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Integration of frequency shift into the forward prediction could improve its performance with appreciably enhanced correlation of the predicted reverberation subspace and the real one, as indicated in eq. (14).…”

Section: Simulationsmentioning

confidence: 99%

“…To solve the above problem, an echo-to-reverberation enhancement method based on decomposition of the time reversal operator (DORT) [12][13][14][15][16] with forward and backward reverberation nulling has been proposed [17]. This method can focus sound energy at the target while nulling the energy at the bottom near the target range simultaneously, substantially enhancing the echo-to-reverberation ratio without a probe source and prior knowledge about the relative scattering intensity of target and bottom.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Reverberation nulling and echo enhancement at low frequency using waveguide invariance

2011

View full text Add to dashboard Cite

Based on the fact that the transfer function vector between a source receiver array and the dominant scatterer of boundary reverberation at a range can be obtained from the corresponding reverberations scattered from this range cell, a reverberation nulling concept using time reversal processing has been proposed. However, current reverberation nulling methods have certain limitations when applied into practice, which would null boundary reverberation and target echo simultaneously. As a solution, a passive reverberation nulling and echo enhancement method at low frequency using waveguide invariance is proposed in this paper. In this method, the reverberation subspace for the target range cell is not obtained directly from the return signals scattered by the target range cell but from the return signals scattered by a range cell located before the target using waveguide invariance, so as to suppress the reverberation embodied in the target echo by passive reverberation nulling. Besides, a range-dependent optimal weighting vector rather than conventional projector matrix is deduced to null the reverberation component meanwhile maximizing the target echo, thereby enhancing the echo-to-reverberation ratio furthest. Numerical simulations in typical range-independent shallow water environment demonstrate the efficacy and the improved performance of the proposed method for echo-to-reverberation enhancement.reverberation nulling, echo-to-reverberation enhancement, waveguide invariance, time reversal

show abstract

Section: Simulationsmentioning

confidence: 99%

mentioning

confidence: 99%

Reverberation nulling and echo enhancement at low frequency using waveguide invariance

2011

View full text Add to dashboard Cite

show abstract

“…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: 99%

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

View full text Add to dashboard Cite

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.

show abstract

“…The mainly discussed imaging methods is chronologically listed as the iterative time reversal mirror imaging (ITRMI) [1][2][3][4][5], the decomposition of time reversal operator (DORT) [6][7][8][9][10][11][12][13] and the time reversal-multiple signal classification method (TR-MUSIC) [14][15][16][17][18][19]. The iterative time reversal mirror imaging is a most direct and intuitional method for target location and imaging considering the spatial and temporal focusing characteristics of time reversal mirror.…”

Section: Introductionmentioning

confidence: 99%

Electromagnetic Subsurface Detection Using Subspace Signal Processing and Half-Space Dyadic Green's Function

Liu¹,

Wang²,

Xiao³

2009

PIER

View full text Add to dashboard Cite

Abstract-In this paper, one of the subspace signal processing methods, namely time reversal multiple signal classification (TR-MUSIC), is firstly employed for electromagnetic subsurface detection where the multilayered dyadic Green's function is used. Therewith, one obtains the improved location and superresolution imaging for underground detecting application. The imaging pseudo-spectrum is accordingly defined for both the echo-mode and transmit-mode TR-MUSIC methods, by analyzing the obtained multistatic response matrix. Based on the theoretical formula, we carry out the numerical simulation using the half-space dyadic Green's function in noisy scenario. The results show that the MUSIC imaging algorithm achieves the enhanced resolution and the transmit-mode method gives more robust output when performance comparison of the four methods is made, therefore indicate the TR-MUSIC could be a good candidate for subsurface detection.

show abstract

Demonstration at sea of the decomposition-of-the-time-reversal-operator technique

Cited by 21 publications

References 15 publications

Reverberation nulling and echo enhancement at low frequency using waveguide invariance

Reverberation nulling and echo enhancement at low frequency using waveguide invariance

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

Electromagnetic Subsurface Detection Using Subspace Signal Processing and Half-Space Dyadic Green's Function

Contact Info

Product

Resources

About