Experimental studies of pulsed signal propagation from the shelf to deep sea

Bezotvetnykh, V. V.; Буренин, А. В.; Morgunov, Yu. N.; Polovinka, Yu. A.

doi:10.1134/s1063771009030130

Cited by 24 publications

(4 citation statements)

References 2 publications

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“…The parameters of designed models are presented in Table 2, where T guard is the time guard interval and f b is the data transmission rate. The time guard interval between OFDM symbols was chosen based on previously conducted experiments at the distances more than 100 km aimed at the estimation of the channel impulse response and data transmission at 400 Hz frequency in current aquatic area, and it is equal to 200 ms [15,16].…”

Section: Numerical Experiments With Fm-ofdm-qpsk In Multipath Channelsmentioning

confidence: 99%

Experimental Estimation of the Constant Envelope FM-OFDM Method Usage in Underwater Acoustic Communication Systems

et al. 2018

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Nowadays, more and more complex methods of signal modulating and processing are actively used for organizing underwater acoustic communication with and between submerged mobile vehicles due to harsh underwater conditions. In this research, the method that is based on multi-frequency signals forming (OFDM) with the constant envelope is applied to the problem. It is based on multi-frequency FM-OFDM signals forming with Quadrature Phase Shift Keying (QPSK) modulated subcarriers and FM spectrum spreading coefficients of 1, 2, 4, and 10. The proposed solution was modeled in a software simulator, which implements a noisy underwater acoustic multipath channel, changing the bit error rate (BER) from 0.15 to 10 −3 . In addition, it was tested during the full-scale data transmission experiments at 25 km distance using a low frequency (400 Hz) underwater acoustic apparatus under conditions of strong impulse noises and quasi-non-stationary channel. The results of in-situ experiments were similar to the ones that were obtained during the simulation.

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Section: Numerical Experiments With Fm-ofdm-qpsk In Multipath Channelsmentioning

confidence: 99%

Experimental Estimation of the Constant Envelope FM-OFDM Method Usage in Underwater Acoustic Communication Systems

et al. 2018

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“…The ocean bottom is assumed to be flat and placed at the depth h = 3 km. We consider only the deep-water propagation, albeit the source in the aforementioned experiments [27,28] was mounted into the bottom in the coastal zone near the Gamov peninsula. The shallow-water part of the waveguide was relatively short, less than 30 km, and didn't have significant bottom features which could remarkably alter ray stability.…”

Section: Model Ofmentioning

confidence: 99%

“…It is recognized that shearless tori can possess extraordinary persistence to chaos [46,[54][55][56][57], therefore, a weakly-divergent beam can survive in the presence of a sound-speed perturbation. Hence, formation of a weaklydivergent beam can be considered as a possible mechanism responsible for unusual stability of near-axial rays, observed in experiments [27,28].…”

Section: Then Introducing New Variablesmentioning

confidence: 99%

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Wave chaos in a randomly inhomogeneous waveguide: Spectral analysis of the finite-range evolution operator

et al. 2013

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The proplem of sound propagation in an oceanic waveguide is considered. Scattering on random inhomogeneity of the waveguide leads to wave chaos. Chaos reveals itself in spectral properties of the finite-range evolution operator (FREO). FREO describes transformation of a wavefield in course of propagation along a finite segment of a waveguide. We study transition to chaos by tracking variations in spectral statistics with increasing length of the segment. Analysis of the FREO is accompanied with ray calculations using the one-step Poincaré map which is the classical counterpart of the FREO. Underwater sound channel in the Sea of Japan is taken for an example. Several methods of spectral analysis are utilized. In particular, we approximate level spacing statistics by means of the Berry-Robnik and Brody distributions, explore the spectrum using the procedure elaborated by A. Relano with coworkers (Relano et al, Phys. Rev. Lett., 2002; Relano, Phys. Rev. Lett., 2008), and analyze modal expansions of the eigenfunctions. We show that the analysis of FREO eigenfunctions is more informative than the analysis of eigenvalue statistics. It is found that near-axial sound propagation in the Sea of Japan preserves stability even over distances of hundreds kilometers. This phenomenon is associated with the presence of a shearless torus in the classical phase space. Increasing of acoustic wavelength degrades scattering, resulting in recovery of localization near periodic orbits of the one-step Poincaré map. Relying upon the formal analogy between wave and quantum chaos, we suggest that the concept of FREO, supported by classical calculations via the one-step Poincaré map, can be efficiently applied for studying chaos-induced decoherence in quantum systems.

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