Scattering of Underwater Acoustic Signals from a Rough, Moving Surface
Author | : Franz B. Tuteur |
Publisher | : |
Total Pages | : 18 |
Release | : 1977 |
Genre | : Doppler effect |
ISBN | : |
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Author | : Franz B. Tuteur |
Publisher | : |
Total Pages | : 18 |
Release | : 1977 |
Genre | : Doppler effect |
ISBN | : |
Author | : Henti Tung |
Publisher | : |
Total Pages | : 211 |
Release | : 1980 |
Genre | : Doppler effect |
ISBN | : |
The scattering of acoustic waves from a randomly varying wind-driven water surface is known to introduce both time and frequency spreading of the received signal. The frequency spreading is thought to be related to surface statistics and water wave motion. Therefore, knowledge of this relation leads to the possibility of predicting surface statistics by analysis of the received acoustic signal. One important feature of the frequency spreading function is that the Doppler sidebands are not equal in magnitude on both sides of the carrier. Unequal sidebands are predicted if the acoustic source and receiver are not located at the same depths below the water surface and if the direction of the surface wave motion is not perpendicular to the vertical plane containing both the source and the receiver. Experimental results from a model tank operated under various wind conditions have verified the existence of unequal Doppler sidebands under these conditions. However, strong asymmetries in sidebands were also observed under conditions under which the previous theory would have predicted no asymmetries at all. For example, strong asymmetries have been observed in the crosswind direction. This research is to explain the asymmetries not predicted in previous theory but discovered under laboratory operations, and to predict other asymmetries not yet found in either the experimental or the theoretical phase.
Author | : |
Publisher | : |
Total Pages | : 254 |
Release | : 1974 |
Genre | : |
ISBN | : |
The general approach to scattering phenomena developed here is now applied specifically to underwater acoustic scattering problems in an isovelocity medium, for the present without absorption and inhomogeneous properties other than the various possible scattering mechanisms themselves. Among the principal new results are (1) the explicit inclusion of doppler, which is shown to produce a nonstationary frequency-modulation of the injected signal; (2) the presence and effects of two orders of inhomogeneities in the second-order media statistics, e.g., poisson, or specular point scatterers (k=1) and continuous scattering elements (k=2); (3) the coherence properties and spectrum of the specular component (k=0); (4) necessary and sufficient conditions for the applicability of the poisson model alone (and of the earlier poisson models cited in the literature); (5) conditions that the medium be a WSSUS medium; (6) for weak scattering interactions, the wave number spectra of surfaces and volumes, including the interaction of surface displacement and motion; (7) various experimental programs for the measurement and underwater remote sensing of the medium; (8) an extensive development of wave surface statistics, particularly point and directional covariances, spectra, and wave number spectra for a variety of sea surface models, including the author's recent model; (9) strong-scattering results; and (10) channel characterizations by means of the local bicovariance and cospreading functions, with specific examples
Author | : Thomas Neighbors |
Publisher | : Elsevier |
Total Pages | : 982 |
Release | : 2017-01-19 |
Genre | : Science |
ISBN | : 0128112476 |
Applied Underwater Acoustics meets the needs of scientists and engineers working in underwater acoustics and graduate students solving problems in, and preparing theses on, topics in underwater acoustics. The book is structured to provide the basis for rapidly assimilating the essential underwater acoustic knowledge base for practical application to daily research and analysis. Each chapter of the book is self-supporting and focuses on a single topic and its relation to underwater acoustics. The chapters start with a brief description of the topic's physical background, necessary definitions, and a short description of the applications, along with a roadmap to the chapter. The subtopics covered within individual subchapters include most frequently used equations that describe the topic. Equations are not derived, rather, assumptions behind equations and limitations on the applications of each equation are emphasized. Figures, tables, and illustrations related to the sub-topic are presented in an easy-to-use manner, and examples on the use of the equations, including appropriate figures and tables are also included. - Provides a complete and up-to-date treatment of all major subjects of underwater acoustics - Presents chapters written by recognized experts in their individual field - Covers the fundamental knowledge scientists and engineers need to solve problems in underwater acoustics - Illuminates, in shorter sub-chapters, the modern applications of underwater acoustics that are described in worked examples - Demands no prior knowledge of underwater acoustics, and the physical principles and mathematics are designed to be readily understood by scientists, engineers, and graduate students of underwater acoustics - Includes a comprehensive list of literature references for each chapter
Author | : Yang Xiao |
Publisher | : CRC Press |
Total Pages | : 352 |
Release | : 2010-05-19 |
Genre | : Computers |
ISBN | : 1420067125 |
A detailed review of underwater channel characteristics, Underwater Acoustic Sensor Networks investigates the fundamental aspects of underwater communication. Prominent researchers from around the world consider contemporary challenges in the development of underwater acoustic sensor networks (UW-ASNs) and introduce a cross-layer approach for effec
Author | : Thomas Rossing |
Publisher | : Springer Science & Business Media |
Total Pages | : 1179 |
Release | : 2007-06-21 |
Genre | : Science |
ISBN | : 0387304460 |
This is an unparalleled modern handbook reflecting the richly interdisciplinary nature of acoustics edited by an acknowledged master in the field. The handbook reviews the most important areas of the subject, with emphasis on current research. The authors of the various chapters are all experts in their fields. Each chapter is richly illustrated with figures and tables. The latest research and applications are incorporated throughout, including computer recognition and synthesis of speech, physiological acoustics, diagnostic imaging and therapeutic applications and acoustical oceanography. An accompanying CD-ROM contains audio and video files.
Author | : F. John Kingsbury |
Publisher | : |
Total Pages | : 371 |
Release | : 1970 |
Genre | : |
ISBN | : |
The results of an experimental investigation into the characteristics of acoustic energy reflected from rough, time-varying surfaces are presented. Theory pertinent to the study of acoustic scattering is also presented to form a predictive base for the experimental work. The experimentally derived amplitude, slope, spectral, and spatial correlation characteristics of the rough surfaces are presented. Measurement results are shown which describe the spatial distribution characteristics of energy scattered from the rough surfaces. Experiments performed to determine the modulation effects imposed on the reflected acoustic energy by the time-varying surfaces are also presented. For all the measurements, the effects on the scattered energy characteristics of shadowing and changes in acoustic frequency, grazing angle, and the direction of acoustic propagation relative to the wave motion are discussed. (Author).