Geoacoustic Inversion Using Backpropagation

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Ocean acoustic sound speed profile (SSP) estimation requires the inversion of acoustic fields using limited observations. Compressive sensing (CS) asserts that certain underdetermined problems can be solved in high resolution, provided their solutions are sparse. Here, CS is used to estimate SSPs in a range-independent shallow ocean by inverting a non-linear acoustic propagation model. It is shown that SSPs can be estimated using CS to resolve fine-scale structure.

Section: Simulation and Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Compressive acoustic sound speed profile estimation

Bianco

Gerstoft

2016

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“…These range-independent parameters were based on previous SW06 inversion results. [32][33][34][35] The source is a 100-900 Hz LFM pulse with 1 s pulse width and PRI. Colored noise was generated using the measured power spectrum of SW06 noise data (see Fig.…”

Section: Simulationsmentioning

confidence: 99%

“…[32][33][34][35] The bottom is characterized with a clay-rich sediment layer of lower velocities that is estimated to be around 1630 m/s 6 20 m/s. The R reflector was noted at 22 m 6 3 m based on vertical incidence chirp data.…”

Section: Experimental Data Analysismentioning

confidence: 99%

Broadband synthetic aperture geoacoustic inversion

Tan

Gerstoft²,

Yardim³

et al. 2013

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A typical geoacoustic inversion procedure involves powerful source transmissions received on a large-aperture receiver array. A more practical approach is to use a single moving source and/or receiver in a low signal to noise ratio (SNR) setting. This paper uses single-receiver, broadband, frequency coherent matched-field inversion and exploits coherently repeated transmissions to improve estimation of the geoacoustic parameters. The long observation time creates a synthetic aperture due to relative source-receiver motion. This approach is illustrated by studying the transmission of multiple linear frequency modulated (LFM) pulses which results in a multi-tonal comb spectrum that is Doppler sensitive. To correlate well with the measured field across a receiver trajectory and to incorporate transmission from a source trajectory, waveguide Doppler and normal mode theory is applied. The method is demonstrated with low SNR, 100-900 Hz LFM pulse data from the Shallow Water 2006 experiment.

“…Voltz and Lu (1994) also established a back-propagation method using ray theory in the time domain. A more detailed overview of back-propagation techniques can be found in Meyer et al (2006), and applications for geoacoustic inversion can be found in Dizaji et al (2002) and Park et al (2010).…”

Section: Introductionmentioning

confidence: 99%

Low-frequency broadband sound source localization using an adaptive normal mode back-propagation approach in a shallow-water ocean

Lin

Newhall

Lynch

2012

A variety of localization methods with normal mode theory have been established for localizing low frequency (below a few hundred Hz), broadband signals in a shallow water environment. Gauss-Markov inverse theory is employed in this paper to derive an adaptive normal mode backpropagation approach. Joining with the maximum a posteriori mode filter, this approach is capable of separating signals from noisy data so that the back-propagation will not have significant influence from the noise. Numerical simulations are presented to demonstrate the robustness and accuracy of the approach, along with comparisons to other methods. Applications to real data collected at the edge of the continental shelf off New Jersey, USA are presented, and the effects of water column fluctuations caused by nonlinear internal waves and shelfbreak front variability are discussed.