Equally Spaced Spherical Array PDF Download
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Author: Andrew K. Chan
Publisher:
ISBN:
Category : Antenna arrays
Languages : en
Pages : 45
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Book Description
The report presents a new method of analyzing the radiation characteristics of a spherical array. The existing method of finding the characteristics of an array on a curved surface using computers does not provide a means of predicting the sidelobe level and beamwidth of the pattern. In this report, the theory of unequally spaced arrays developed by Ishimaru is applied to this problem and the radiation characteristic is found to behave as sin(u)/u. The elements of the array are arranged as a series of circular arrays of different radii on the spherical surface. The resulting radiation pattern for constant amplitude and element spacing of one wave length is discussed in detail. The validity of the theory is demonstrated by an experimental spherical array which employs half-wavelength dipole elements on an Eccoform sphere. Due to the difficulty of exciting each element of the array a plane wave is used to excite the array. Scattered wave is measured and compared with the theory. (Author).
Author: Andrew K. Chan
Publisher:
ISBN:
Category : Antenna arrays
Languages : en
Pages : 45
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Book Description
The report presents a new method of analyzing the radiation characteristics of a spherical array. The existing method of finding the characteristics of an array on a curved surface using computers does not provide a means of predicting the sidelobe level and beamwidth of the pattern. In this report, the theory of unequally spaced arrays developed by Ishimaru is applied to this problem and the radiation characteristic is found to behave as sin(u)/u. The elements of the array are arranged as a series of circular arrays of different radii on the spherical surface. The resulting radiation pattern for constant amplitude and element spacing of one wave length is discussed in detail. The validity of the theory is demonstrated by an experimental spherical array which employs half-wavelength dipole elements on an Eccoform sphere. Due to the difficulty of exciting each element of the array a plane wave is used to excite the array. Scattered wave is measured and compared with the theory. (Author).
Author: Boaz Rafaely
Publisher: Springer
ISBN: 3319995618
Category : Technology & Engineering
Languages : en
Pages : 193
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Book Description
This book provides a comprehensive introduction to the theory and practice of spherical microphone arrays, and was written for graduate students, researchers and engineers who work with spherical microphone arrays in a wide range of applications. The new edition includes additions and modifications, and references supplementary Matlab code to provide the reader with a straightforward start for own implementations. The book is also accompanied by a Matlab manual, which explains how to implement the examples and simulations presented in the book. The first two chapters provide the reader with the necessary mathematical and physical background, including an introduction to the spherical Fourier transform and the formulation of plane-wave sound fields in the spherical harmonic domain. In turn, the third chapter covers the theory of spatial sampling, employed when selecting the positions of microphones to sample sound pressure functions in space. Subsequent chapters highlight various spherical array configurations, including the popular rigid-sphere-based configuration. Beamforming (spatial filtering) in the spherical harmonics domain, including axis-symmetric beamforming, and the performance measures of directivity index and white noise gain are introduced, and a range of optimal beamformers for spherical arrays, including those that achieve maximum directivity and maximum robustness are developed, along with the Dolph–Chebyshev beamformer. The final chapter discusses more advanced beamformers, such as MVDR (minimum variance distortionless response) and LCMV (linearly constrained minimum variance) types, which are tailored to the measured sound field. Mathworks kindly distributes the Matlab sources for this book on https://www.mathworks.com/matlabcentral/fileexchange/68655-fundamentals-of-spherical-array-processing.
Author: Lawrence J. Ziomek
Publisher: CRC Press
ISBN: 1000617866
Category : Technology & Engineering
Languages : en
Pages : 770
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Book Description
An Introduction to Sonar Systems Engineering Second Edition Important topics that are fundamental to the understanding of modern-day sonar systems engineering are featured. Linear, planar, and volume array theory, including near-field and far-field beam patterns, beam steering, and array focusing, are covered. Real-world arrays such as the twin-line planar array and a linear array of triplets, which are solutions to the port/starboard (left/right) ambiguity problem associated with linear towed arrays, are examined in detail. Detailed explanations of the fundamentals of side-looking (side-scan) and synthetic-aperture sonars are presented. Bistatic scattering with moving platforms is explored with derivations of exact solutions for the time delay, time-compression/time-expansion factor, and Doppler shift at a receiver for both the scattered and direct acoustic paths. Time-domain and frequency-domain descriptions, and the design of CW, LFM, and Doppler-invariant HFM pulses, are explained. Target detection in the presence of reverberation and noise is examined. Time-domain and frequency-domain descriptions of MFSK, MQAM, and OFDM underwater acoustic communication signals are also discussed. Although the book is mathematically rigorous, it is written in a tutorial style. Many useful, practical design and analysis equations for both passive and active sonar systems are derived from first principles. No major steps in the derivation of important results are skipped – all assumptions and approximations are clearly stated. Particular attention is paid to the correct units for functions and parameters. Many figures, tables, examples, and practical homework problems at the end of each chapter are included to aid in the understanding of the material covered. New to the Second Edition Chapter 15 Synthetic-Aperture Sonar Chapter 13, Section 13.3, The Rectangular-Envelope HFM Pulse Chapter 10, Section 10.7, Moving Platforms, was rewritten, which allowed for the elimination of Appendix 10C from the first edition New explanations/discussions were added to Subsections 1.2.1 and 1.3.1 in Chapter 1 Appendix 1A was rewritten and the new Table 1A-1 was added to Chapter 1 A solutions manual is available for adopting professors
Author: Lawrence Ziomek
Publisher: CRC Press
ISBN: 1000108600
Category : Technology & Engineering
Languages : en
Pages : 707
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Book Description
Providing a wealth of information on fundamental topics in the areas of linear air and underwater acoustics, as well as space-time signal processing, this book provides real-world design and analysis equations. As a consequence of the interdisciplinary nature of air and underwater acoustics, the book is divided into two parts: Acoustic Field Theory and Space-Time Signal Processing. It covers the fundamentals of acoustic wave propagation as well as the fundamentals of aperture theory, array theory, and signal processing. Starting with principles and using a consistent, mainly standard notation, this book develops, in detail, basic results that are useful in a variety of air and underwater acoustic applications. Numerous figures, examples, and problems are included.
Author: Harry L. Van Trees
Publisher: John Wiley & Sons
ISBN: 0471463833
Category : Technology & Engineering
Languages : en
Pages : 1472
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Book Description
Well-known authority, Dr. Van Trees updates array signalprocessing for today's technology This is the most up-to-date and thorough treatment of thesubject available Written in the same accessible style as Van Tree's earlierclassics, this completely new work covers all modern applicationsof array signal processing, from biomedicine to wirelesscommunications
Author: Qihu Li
Publisher: Springer Science & Business Media
ISBN: 3642182909
Category : Science
Languages : en
Pages : 658
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Book Description
"Digital Sonar Design in Underwater Acoustics Principles and Applications" provides comprehensive and up-to-date coverage of research on sonar design, including the basic theory and techniques of digital signal processing, basic concept of information theory, ocean acoustics, underwater acoustic signal propagation theory, and underwater signal processing theory. This book discusses the general design procedure and approaches to implementation, the design method, system simulation theory and techniques, sonar tests in the laboratory, lake and sea, and practical validation criteria and methods for digital sonar design. It is intended for researchers in the fields of underwater signal processing and sonar design, and also for navy officers and ocean explorers. Qihu Li is a professor at the Institute of Acoustics, Chinese Academy of Sciences, and an academician of the Chinese Academy of Sciences.
Author: Naval Underwater Systems Center (U.S.)
Publisher:
ISBN:
Category : Submarine warfare
Languages : en
Pages : 958
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Book Description
Author:
Publisher:
ISBN:
Category : Antennas (Electronics)
Languages : en
Pages : 904
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Book Description
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 260
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Book Description
Author: Daniel Malacara
Publisher: John Wiley & Sons
ISBN: 0471484040
Category : Science
Languages : en
Pages : 882
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Book Description
The purpose of this third edition is to bring together in a single book descriptions of all tests carried out in the optical shop that are applicable to optical components and systems. This book is intended for the specialist as well as the non-specialist engaged in optical shop testing. There is currently a great deal of research being done in optical engineering. Making this new edition very timely.
