Principles of underwater sound

408 Pages·1975·27.239 MB·English

by  Robert J Urick, Urick

cond
Edition
Robert Urick
J.
. .
PRINCIPLES OF
UNDERWATER SOUND
Second Edition
BY ROBERT URICK
J.
Formerly, U.S. Naval SurfaceWeapons Center,
SilverSpring, Md.
Thefirst edition ofthisvolume, published as
Principlesof UnderwaterSoundforEngineers,
has becomethe "standard" reference on
underwateracoustics. This Second Edition
offers a completetreatmentof nearly all
aspectsof underwatersound, based on the
"sonarequations." It describesthe various
causes, effects, and phenomena of underwater
sound givesquantitative information asthe
. . .
basisfor practical sonar problem solving . .
and offers manyvaluable referencesto the
unclassified literature. The book stresses
practical principles and their application-
bridging thegap betweentheory and current
hardware.
ThisSecond Edition includes substantial
changeswhich bring the booktotally upto
date. It covers newfindings and techniques in
the active, developing field of underwater
acoustics, and presents new material on such
subjects as
. .
• nonlinear (parametric) sonars
• synthetic aperture arrays
• techniquesfor reducing target strength and
flow noise
• theeffecton detectabilityofsignal
fluctuations and multipletargets
Newgraphic material has been added to
enhancetheusefulnessofthebookineveryday
work. This new material includes ... a
nomogram forthedesign of parametric arrays
graphical aidsfordesigning steered arrays
. . .
and curvesforpredictingtheoccurrence and
the rangeofconvergencezones and other
. . .
work-saving devices. Another newfeatureof
this edition isthe usethroughoutofthe new
American acoustical standard ofone
micropascal (1 ,uPa).Asan added convenience,
metric unitsfor manyotherquantities are
included along with their English equivalents.
The book's unified presentation focuses on
the "sonarequations," which are derived in
an earlychapterand are subsequently
employed astopics offollowing chapters. In
thefinal chapter, the usesofthe equationsare
illustrated in a numberof applications.
(continuedon backflap)
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principles
of
underwater
sound

principles
of
underwater
sound
First edition published in 1967 under the title
"Principles of Underwater Sound for Engineers"
Robert J. Urick
Formerly SeniorResearch Physicist
U.S. NavalSurface Weapons CenterHeadquarters
White Oak, Silver Spring, Maryland
McGraw-Hill Book Company
New York St. Louis San Francisco Aukland Dusseldorf
Johannesburg Kuala Lumpur London Mexico Montreal
NewDelhi Panama Paris Sao Paulo Singapore
Sydney Tokyo Toronto
Library of Congress Cataloging in Publication Data
Urick, Robert J
Principles of underwater sound.
Published in 1967 under title: Principles of
underwater sound for engineers.
Includes bibliographies and index.
1. Underwater acoustics. I. Title.
QC242.2.U74 1975 534'.23 75-17514
ISBN 0-07-066086-7
©
Copyright 1975, 1967 by McGraw-Hill, Inc. All rights re-
served. Printed in the United States of America. No part
of this publication may be reproduced, stored in a retrieval
system, or transmitted, in any form or by any means, elec-
tronic, mechanical, photocopying, recording, or otherwise, with-
out the priorwritten permission of the publisher.
KPKP
567890 78432109
The editors for this book were Jeremy Robinson
and Margaret Lamb, the designer was NaomiAuerbach,
and the production supervisor was Teresa F. Leaden.
It wasset in Lino 21 by Bi-Comp, Inc.
Printedand bound by The Kingsport Press.
Preface to the Revised Edition ix
Preface to First Edition xi
Abbreviations Used in the Book xiii
ONE The Nature of Sonar 1
1.1 Historical Survey 2
1.2 Postwar Developments 6
1.3 Nonmilitary Uses of UnderwaterSound 7
1.4 Military Uses of Underwater Sound 7
1.5 Some Basic Concepts 12
1.6 The New Reference Unit and the Decibel 13
References 15
TWO
The Sonar Equations 16
2.1 Basic Considerations 17
2.2 TheActive and Passive Equations 18
2.3 Names for Various Combinations ofParameters 21
2.4 Echo, Noise, and Reverberation Level as Functions ofRange 22
2.5 Transient Form of the SonarEquations 24
2.6 Statement of the Equations 27
2.7 Limitations ofthe SonarEquations 28
References 28
THREE Properties of Transducer Arrays: Directivity Index 29
. .
3.1 Array Gain 30
3.2 Receiving Directivity Index 37
3.3 Limitations of Directivity Index 39
3.4 Transducer Responses 39
3.5 Calibration Methods 40
3.6 Reciprocity Calibration 46
3.7 Calibration of Large Arrays 49
3.8 Beam Patterns 49
3.9 The Product Theorem and the Mills Cross 57
3.10 Shading and Superdirectivity 57
3.11 Adaptive Beam Forming 59
3.12 Multiplicative Arrays 60
References 63
Generation of Underwater Sound: Projector Source
Level 66
4.1 Relation between Source Level and Radiated Acoustic Power 67
4.2 Limitations on Sonar Power 70
4.3 Nonlinear Effects in Sonar 75
4.4 Explosions as Sources of Underwater Sound 79
References 90
Propagation of Sound in the Sea: Transmission Loss, I 93
5.1 Introduction 93
5.2 Spreading Laws 94
5.3 Absorption ofSound in the Sea 96
5.4 Velocity of Sound in the Sea 104
5.5 Velocity Structure of the Sea 109
5.6 Propagation Theory and Ray Tracing 114
5.7 The Sea Surface 121
5.8 The Sea Bottom 126
References 132
Propagation of Sound in the Sea: Transmission Loss, 11 136
6.1 The Mixed-Layer Sound Channel 136
6.2 The Deep Sound Channel 146
6.3 Caustics and Convergence Zones 151
6.4 Internal Sound Channels 154
6.5 Arctic Propagation 156
6.6 The Shallow-Water Channel 159
6.7 Fluctuation of Transmitted Sound 169
6.8 Deep-Sea Paths and Losses: A Summary J74
References 177
The Noise Background of the Sea: Ambient-ISoise Level 181
7.1 Sources ofAmbient Noise in Deep Water 182
7.2 Deep-Water Spectra 183
7.3 Shallow-Water Ambient Noise 189
7.4 Variability of Ambient Noise 192
7.5 Intermittent Sources of AmbientNoise 193
7.6 Effect of Depth 197
7.7 Amplitude Distribution 199
7.8 Noise in Ice-covered Waters 200