|
Applied Underwater Acoustics |
2 |
|
|
Applied Underwater Acoustics |
4 |
|
|
Copyright |
5 |
|
|
Dedication |
6 |
|
|
Contents |
8 |
|
|
List of Contributors |
14 |
|
|
Preface |
16 |
|
|
1 - General Characteristics of the Underwater Environment |
18 |
|
|
1.1 INTRODUCTION |
18 |
|
|
1.2 A BRIEF EXPOSITION OF THE HISTORY OF UNDERWATER ACOUSTICS |
22 |
|
|
1.2.1 UNDERWATER ACOUSTICS BEFORE 1912 |
23 |
|
|
1.2.2 THE YEARS 1912 THROUGH 1918 |
25 |
|
|
1.2.3 THE YEARS 1919 THROUGH 1939 |
27 |
|
|
1.2.4 THE YEARS 1940 THROUGH 1946 |
29 |
|
|
1.2.5 THE YEARS AFTER 1946 |
29 |
|
|
1.3 INTERNATIONAL STANDARD UNITS |
32 |
|
|
1.4 THE DECIBEL SCALES |
33 |
|
|
1.5 FEATURES OF OCEANOGRAPHY |
35 |
|
|
1.5.1 SOUND SPEED PROFILES |
35 |
|
|
1.5.2 THERMOCLINES |
39 |
|
|
1.5.3 ARCTIC REGIONS |
41 |
|
|
1.5.4 DEEP ISOTHERMAL LAYERS |
46 |
|
|
1.5.5 EXPRESSIONS FOR THE SPEED OF SOUND |
50 |
|
|
1.5.6 SURFACE WAVES |
53 |
|
|
1.5.7 INTERNAL WAVES |
60 |
|
|
1.5.8 BUBBLES FROM WAVE BREAKING |
63 |
|
|
1.5.9 OCEAN ACIDIFICATION |
74 |
|
|
1.5.10 DEEP-OCEAN HYDROTHERMAL FLOWS |
77 |
|
|
1.5.11 EDDIES, FRONTS, AND LARGE-SCALE TURBULENCE |
80 |
|
|
1.5.12 DIURNAL AND SEASONAL CHANGES |
82 |
|
|
1.6 SONAR EQUATIONS |
83 |
|
|
1.6.1 DEFINITIONS OF THE SONAR EQUATION TERMS |
84 |
|
|
1.6.2 SONAR EQUATIONS |
88 |
|
|
1.7 ABBREVIATIONS |
92 |
|
|
Acknowledgment |
93 |
|
|
REFERENCES |
93 |
|
|
2 - Sound Propagation |
102 |
|
|
2.1 THE CONCEPT OF WAVES |
102 |
|
|
2.1.1 THE WAVE EQUATION FOR AN INVISCID FLUID |
103 |
|
|
2.1.2 THE HELMHOLTZ EQUATION |
106 |
|
|
2.1.3 HARMONIC WAVES |
108 |
|
|
2.1.4 PLANE WAVES |
110 |
|
|
2.1.5 CYLINDRICAL WAVES |
115 |
|
|
2.1.6 SPHERICAL WAVES |
119 |
|
|
2.1.7 PLANE WAVE DECOMPOSITION OF A SPHERICAL WAVE |
122 |
|
|
2.2 SOUND PROPAGATION IN A VISCOUS FLUID |
124 |
|
|
2.2.1 DISPERSION FORMULAS |
125 |
|
|
2.2.2 KRAMERS–KRONIG DISPERSION RELATIONS |
127 |
|
|
2.2.3 CAUSALITY AND STOKES' EQUATION |
129 |
|
|
2.2.4 PULSE PROPAGATION IN A VISCOUS FLUID |
130 |
|
|
2.3 SOUND WAVES AND SHEAR WAVES IN MARINE SEDIMENTS |
134 |
|
|
2.3.1 THE BIOT THEORY |
135 |
|
|
2.3.2 THE GRAIN-SHEARING THEORY |
137 |
|
|
2.4 SOURCE OR RECEIVER IN MOTION |
145 |
|
|
2.4.1 DOPPLER FREQUENCY SHIFTS (SOURCE STATIONARY, OBSERVER IN MOTION) |
146 |
|
|
2.4.2 DOPPLER FREQUENCY SHIFTS (OBSERVER STATIONARY, SOURCE IN MOTION) |
148 |
|
|
2.4.3 ACOUSTIC FIELD FROM A MOVING SOURCE |
149 |
|
|
2.5 SOUND REFLECTION AND TRANSMISSION AT A FLUID–FLUID BOUNDARY |
153 |
|
|
2.5.1 STRUCTURE OF THE SOLUTION |
154 |
|
|
2.5.2 THE STATIONARY PHASE APPROXIMATION |
158 |
|
|
2.5.3 PLANE-WAVE REFLECTION |
159 |
|
|
2.5.4 WESTON'S EFFECTIVE DEPTH |
163 |
|
|
2.5.5 PLANE-WAVE REFRACTION |
164 |
|
|
2.5.6 THE LATERAL WAVE |
167 |
|
|
2.6 THE “IDEAL” WAVEGUIDE |
173 |
|
|
2.6.1 PLANE WAVES AND NORMAL MODES |
173 |
|
|
2.6.2 THE ACOUSTIC FIELD IN THE IDEAL WAVEGUIDE |
176 |
|
|
2.6.3 INTERMODAL INTERFERENCE |
178 |
|
|
2.7 THE PEKERIS CHANNEL |
179 |
|
|
2.7.1 THE INTEGRAL-TRANSFORM SOLUTION FOR THE FIELD |
180 |
|
|
2.7.2 THE NORMAL MODE SOLUTION |
182 |
|
|
2.7.3 THE CHARACTERISTIC EQUATION |
184 |
|
|
2.8 THREE-DIMENSIONAL PROPAGATION |
187 |
|
|
2.8.1 HORIZONTAL REFRACTION |
188 |
|
|
2.8.2 THE “IDEAL” WEDGE |
189 |
|
|
2.8.3 THE SHADOW EDGE |
192 |
|
|
2.8.4 INTRAMODAL INTERFERENCE |
195 |
|
|
2.8.5 THE PENETRABLE WEDGE |
196 |
|
|
Acknowledgment |
197 |
|
|
REFERENCES |
197 |
|
|
3 - Sound Propagation Modeling |
202 |
|
|
3.1 RAY MODELS |
205 |
|
|
3.1.1 A PARTICULAR TYPE OF ANALYTIC 2-D RAY TRACING |
206 |
|
|
3.1.1.1 Kinematic Ray Tracing |
207 |
|
|
3.1.1.2 Dynamic Ray Tracing |
207 |
|
|
3.1.1.3 Caustics |
209 |
|
|
3.1.1.4 Coherent Computation of Propagation Loss and Propagation Time Series |
209 |
|
|
3.1.2 EXAMPLE |
211 |
|
|
3.2 WAVE NUMBER INTEGRATION OR SPECTRAL METHODS |
213 |
|
|
3.2.1 SOLUTION OF THE DEPTH-DEPENDENT ODE SYSTEMS |
215 |
|
|
3.2.1.1 Recursive Computation of Reflection-Coefficient Matrices for the Solid Bottom |
216 |
|
|
3.2.1.2 Propagator Matrices for the Fluid Region |
219 |
|
|
3.2.1.3 Alternative Treatment of the Fluid Region |
220 |
|
|
3.2.1.4 Final Remarks |
221 |
|
|
3.2.2 ADAPTIVE INTEGRATION |
222 |
|
|
3.2.3 EXAMPLE |
223 |
|
|
3.3 NORMAL MODE PROPAGATION MODELS |
225 |
|
|
3.3.1 MODAL WAVE NUMBERS |
226 |
|
|
3.3.2 MODE FUNCTIONS |
227 |
|
|
3.3.3 EXCITATION COEFFICIENTS |
229 |
|
|
3.3.4 RANGE-DEPENDENT MEDIA |
230 |
|
|
3.3.4.1 Equations Relating the Modal Expansion Coefficients |
231 |
|
|
3.3.4.2 Solution in Terms of Reflection-Coefficient Matrices |
233 |
|
|
3.3.4.3 Final Remarks |
234 |
|
|
3.3.5 EXAMPLES |
235 |
|
|
3.3.5.1 Range-Invariant Media |
235 |
|
|
3.3.5.2 Range-Dependent Media |
239 |
|
|
3.4 PARABOLIC EQUATION METHODS |
242 |
|
|
3.4.1 INTERFACE CONDITIONS AT THE VERTICAL RANGE-SEGMENT INTERFACES |
244 |
|
|
3.4.2 NUMERICAL SOLUTION METHODS |
245 |
|
|
3.4.2.1 Start Solution |
245 |
|
|
3.4.2.2 Rational-Function Approximations for the Relevant Operators |
247 |
|
|
3.4.2.3 Depth Discretization and Range Integration |
249 |
|
|
3.4.3 EXTENDED AND ALTERNATIVE PE APPROACHES |
250 |
|
|
3.4.3.1 Extension to Media That Vary Regionwise Smoothly With Range and Depth |
250 |
|
|
3.4.3.2 Coordinate Transformation Techniques |
251 |
|
|
3.4.3.3 Two-Way PE Approaches |
252 |
|
|
3.4.3.4 Extension to Fluid-Solid Media |
252 |
|
|
3.4.4 EXAMPLES |
253 |
|
|
3.5 FINITE-DIFFERENCE AND FINITE-ELEMENT METHODS |
256 |
|
|
3.5.1 ONE-DIMENSIONAL FEM AND FDM FOR PARABOLIC AND NORMAL-MODE EQUATIONS |
257 |
|
|
3.5.1.1 Application to Normal Modes |
258 |
|
|
3.5.2 TWO-DIMENSIONAL FEM AND FDM FOR THE HELMHOLTZ EQUATION |
259 |
|
|
3.5.2.1 FEM Discretization |
260 |
|
|
3.5.2.2 FDM Discretization |
261 |
|
|
3.5.2.3 Methods to Solve the Linear Equation System and Possibilities to Reduce Its Size |
262 |
|
|
3.5.3 TIME-DOMAIN MODELING |
263 |
|
|
3.5.3.1 FEM Discretization |
263 |
|
|
3.5.3.2 FDM Discretization |
263 |
|
|
3.5.3.3 Numerical Dispersion, Time Integration, and Stability |
264 |
|
|
3.5.3.4 Including Absorption |
265 |
|
|
3.5.3.5 Some Recent Developments |
265 |
|
|
3.5.4 EXAMPLES |
266 |
|
|
3.6 3-D SOUND PROPAGATION MODELS |
268 |
|
|
3.6.1 MODELING HORIZONTAL REFRACTION BY A SLOPING BOTTOM OR CHANGING SOUND-SPEED PROFILE |
270 |
|
|
3.6.1.1 Fourier Transformation With Respect to the y-Coordinate |
271 |
|
|
3.6.1.2 Equations Relating the Modal Expansion Coefficients |
272 |
|
|
3.6.1.3 Solution in Terms of Reflection-Coefficient Matrices |
273 |
|
|
3.6.1.4 Final Remarks |
273 |
|
|
3.6.2 MODELING DIFFRACTION AROUND A CYLINDRICALLY SYMMETRIC ANOMALY |
274 |
|
|
3.6.2.1 Fourier Series With Respect to the ? Coordinate |
274 |
|
|
3.6.2.2 Equations Relating the Modal Expansion Coefficients |
276 |
|
|
3.6.2.3 Solution in Terms of Reflection-Coefficient Matrices |
277 |
|
|
3.6.2.4 Final Remarks |
278 |
|
|
3.6.3 EXAMPLES |
278 |
|
|
LIST OF ABBREVIATIONS AND SYMBOLS |
280 |
|
|
Acknowledgments |
281 |
|
|
REFERENCES |
281 |
|
|
4 - Absorption of Sound in Seawater |
290 |
|
|
4.1 PHYSICS AND PHENOMENA |
290 |
|
|
4.2 EXPERIMENTAL DATA |
292 |
|
|
4.2.1 ABSORPTION PRESSURE DEPENDENCE |
295 |
|
|
4.2.2 ABSORPTION TEMPERATURE DEPENDENCE |
297 |
|
|
4.2.3 PH DEPENDENCE OF ABSORPTION |
299 |
|
|
4.2.4 SALINITY DEPENDENCE |
299 |
|
|
4.3 SOUND ABSORPTION MECHANISMS |
300 |
|
|
4.3.1 SOUND ABSORPTION IN FRESHWATER |
300 |
|
|
4.3.2 MOLECULAR CHEMICAL RELAXATION PROCESSES |
301 |
|
|
4.3.2.1 Temperature Dependence |
303 |
|
|
4.3.2.2 Pressure Effects |
305 |
|
|
4.4 FORMULAS AND EXPRESSIONS |
305 |
|
|
4.4.1 FRANCOIS AND GARRISON EQUATION FOR SOUND ABSORPTION IN SEAWATER |
305 |
|
|
4.4.1.1 Boric Acid Coefficients |
306 |
|
|
4.4.1.2 Magnesium Sulfate Coefficients |
307 |
|
|
4.4.1.3 Pure Water Contribution |
307 |
|
|
4.4.2 AINSLIE AND MCCOLM SIMPLIFIED EQUATION FOR SOUND ABSORPTION IN SEAWATER |
307 |
|
|
4.5 SYMBOLS AND ABBREVIATIONS |
308 |
|
|
REFERENCES |
309 |
|
|
5 - Scattering of Sound |
314 |
|
|
5.1 PHYSICS AND PHENOMENA |
314 |
|
|
5.2 SCATTERING FROM POINT-LIKE OBJECTS |
320 |
|
|
5.2.1 SINGLE OBJECTS |
320 |
|
|
5.2.1.1 Rigid and Elastic Spheres |
320 |
|
|
5.2.1.2 Gas Bubbles |
322 |
|
|
5.2.1.3 Single Fish |
324 |
|
|
5.2.1.4 Canonically Shaped Objects |
325 |
|
|
5.2.1.5 Submarines |
327 |
|
|
5.2.2 MULTIPLE OBJECTS |
330 |
|
|
5.2.2.1 Fish Schools |
331 |
|
|
5.2.2.2 Bubble Clouds |
331 |
|
|
5.2.2.3 Deep Scattering Layer |
334 |
|
|
5.2.2.4 Suspended Sediments |
335 |
|
|
5.3 SCATTERING FROM EXTENDED, NEARLY PLANE, ROUGH SURFACES |
335 |
|
|
5.3.1 BRAGG SCATTERING |
337 |
|
|
5.3.2 REFLECTION FROM FACETS |
337 |
|
|
5.3.3 LAMBERT'S LAW |
338 |
|
|
5.3.4 SCATTERING FROM THE SEA SURFACE |
339 |
|
|
5.3.5 SCATTERING FROM THE SEABED |
343 |
|
|
5.4 THEORETICAL BASIS FOR SCATTERING CALCULATIONS |
349 |
|
|
5.4.1 THE PERTURBATION APPROXIMATION |
349 |
|
|
5.4.2 THE HELMHOLTZ–KIRCHHOFF METHOD |
352 |
|
|
5.4.3 SCATTERING FROM SURFACES WITH TWO SCALES OF ROUGHNESS |
354 |
|
|
5.5 SCATTERING FROM CURVED, ROUGH SURFACES |
357 |
|
|
5.6 REVERBERATION |
363 |
|
|
5.7 SYMBOLS AND ABBREVIATIONS |
370 |
|
|
REFERENCES |
375 |
|
|
6 - Ambient Noise |
380 |
|
|
6.1 PHYSICS AND PHENOMENA |
380 |
|
|
6.2 SOURCES OF AMBIENT NOISE |
381 |
|
|
6.2.1 TIDES AND HYDROSTATIC EFFECTS OF WAVES |
381 |
|
|
6.2.2 SEISMIC ACTIVITIES |
383 |
|
|
6.2.3 TURBULENCE |
384 |
|
|
6.2.4 SURFACE PHENOMENA |
384 |
|
|
6.2.4.1 Breaking Waves |
385 |
|
|
6.2.4.2 Nonlinear Wave–Wave Interaction |
386 |
|
|
6.2.4.3 Bubbles |
387 |
|
|
6.2.5 PRECIPITATION |
389 |
|
|
6.2.6 BIOLOGICAL ACTIVITY |
391 |
|
|
6.2.7 ICE NOISE |
392 |
|
|
6.2.8 SHIPPING |
392 |
|
|
6.2.9 OTHER MAN-MADE (ANTHROPOGENIC) SOURCES |
396 |
|
|
6.2.10 SEDIMENT FLOW–GENERATED NOISE |
397 |
|
|
6.2.11 THERMAL NOISE |
397 |
|
|
6.3 SPECTRA OF AMBIENT NOISE |
398 |
|
|
6.3.1 DEEP-WATER SPECTRA |
399 |
|
|
6.3.2 SHALLOW-WATER SPECTRA |
400 |
|
|
6.4 DIRECTIVITY OF AMBIENT NOISE |
401 |
|
|
6.4.1 NOISE PROPAGATION |
401 |
|
|
6.5 COHERENCE OF AMBIENT NOISE |
405 |
|
|
6.6 SELF-NOISE |
407 |
|
|
6.7 AMPLITUDE DISTRIBUTIONS FOR UNDERWATER NOISE |
409 |
|
|
6.8 SYMBOLS AND ABBREVIATIONS |
414 |
|
|
REFERENCES |
416 |
|
|
7 - Shallow-Water Acoustics |
420 |
|
|
7.1 WHAT IS SHALLOW-WATER ACOUSTICS? |
420 |
|
|
7.1.1 MILITARY APPLICATIONS |
421 |
|
|
7.1.2 DUAL-USE APPLICATIONS |
422 |
|
|
7.1.3 OCEAN SCIENCES APPLICATIONS |
422 |
|
|
7.1.4 COMMERCIAL APPLICATIONS |
423 |
|
|
7.2 PHYSICS AND PHENOMENA |
423 |
|
|
7.2.1 SOURCE LEVEL TERM |
423 |
|
|
7.2.1.1 Example: Integrating Pseudorandom Noise Sequences and Frequency Modulation Sweeps for Signal Gain |
426 |
|
|
7.2.2 ARRAY GAIN TERM |
428 |
|
|
7.2.2.1 Examples: Mode Filtration Techniques in Shallow Water |
430 |
|
|
7.2.2.1.1 Time Resolution of Modes |
430 |
|
|
7.2.2.1.2 Amplitude-Shaded Vertical Array Mode Resolution |
430 |
|
|
7.2.2.1.3 Vertical Array Steering |
432 |
|
|
7.2.2.1.4 Horizontal Array Steering |
432 |
|
|
7.2.2.1.5 Focused Array Mode Filtration |
433 |
|
|
7.2.3 TRANSMISSION LOSS TERM |
433 |
|
|
7.2.3.1 Simple Geometric Spreading Intensity Arguments |
433 |
|
|
7.2.3.2 Popular Propagation Theories and Their Application(s) to Shallow Water |
434 |
|
|
7.2.3.2.1 Ray Theory |
434 |
|
|
7.2.3.2.2 Normal Modes and Shallow Water |
441 |
|
|
7.2.3.2.3 Vertical Modes and Horizontal Rays |
448 |
|
|
7.2.3.2.3.1 Example: Ducting Between Nonlinear Internal Waves |
449 |
|
|
7.2.3.2.4 Parabolic Equation |
451 |
|
|
7.2.3.2.5 Wave Number Integration |
453 |
|
|
7.2.4 AMBIENT NOISE TERM |
454 |
|
|
7.2.5 REVERBERATION TERM |
459 |
|
|
7.2.5.1 The Bottom Boundary Layer |
462 |
|
|
7.2.5.2 Water Column Reverberation |
463 |
|
|
7.2.5.3 Sea Surface Scattering and Reverberation |
463 |
|
|
7.2.5.4 The Sea Surface Plus Bubble Scattering and Reverberation |
463 |
|
|
7.3 SOME ADDITIONAL TOPICS OF INTEREST IN SHALLOW-WATER ACOUSTICS |
465 |
|
|
7.3.1 ONE- AND TWO-LAYER WATER COLUMN SOUND SPEED PROFILES IN SHALLOW-WATER ACOUSTICS |
465 |
|
|
7.3.2 THE OPTIMUM FREQUENCY |
466 |
|
|
7.3.3 ARRIVAL STRUCTURES IN SHALLOW-WATER AND RAY/MODE RESOLUTION |
467 |
|
|
7.3.4 WAVEGUIDE INVARIANT |
468 |
|
|
7.3.5 INTENSITY FLUCTUATION STATISTICS |
469 |
|
|
7.4 SOME NEWER TOPICS |
472 |
|
|
7.4.1 THE SHELF BREAK, SLOPE, AND CANYON REGIONS AND THE TRANSITION TO DEEP WATER |
472 |
|
|
7.4.2 ARCTIC SHALLOW-WATER ACOUSTICS |
473 |
|
|
7.4.3 CLIMATE CHANGE AND SHALLOW-WATER ACOUSTICS |
474 |
|
|
LIST OF ACRONYMS |
475 |
|
|
LIST OF SYMBOLS IN EQUATIONS |
476 |
|
|
REFERENCES |
477 |
|
|
APPENDIX 7.A1 |
480 |
|
|
8 - The Seafloor |
486 |
|
|
8.1 BACKGROUND AND HISTORY |
487 |
|
|
8.2 THE ORIGIN AND NATURE OF SEAFLOOR SEDIMENTS |
488 |
|
|
8.3 ACOUSTICS OF SEDIMENTS |
488 |
|
|
8.3.1 FLUID MODEL |
489 |
|
|
8.3.2 ELASTIC MODEL |
491 |
|
|
8.3.3 POROELASTIC MODEL |
494 |
|
|
8.4 MODEL FOR SOUND SCATTERING BY THE SEAFLOOR |
499 |
|
|
8.4.1 MODEL PARAMETERS |
500 |
|
|
8.4.2 SCATTERING BY SEAFLOOR ROUGHNESS |
501 |
|
|
8.4.3 SCATTERING BY SEAFLOOR HETEROGENEITY |
503 |
|
|
8.4.4 SCATTERING MODEL EXAMPLES |
505 |
|
|
8.5 SEDIMENT PHYSICAL PROPERTIES |
511 |
|
|
8.5.1 GRAIN SIZE DISTRIBUTION |
512 |
|
|
8.5.2 SEDIMENT BULK DENSITY AND POROSITY |
516 |
|
|
8.5.3 PORE FLUID AND PORE SPACE PROPERTIES |
518 |
|
|
8.5.4 PERMEABILITY |
519 |
|
|
8.5.5 GRAIN PROPERTIES |
520 |
|
|
8.5.6 SEDIMENT TYPE |
520 |
|
|
8.5.7 SUMMARY OF SEDIMENT PROPERTIES |
524 |
|
|
8.6 SEDIMENT GEOACOUSTIC PROPERTIES |
524 |
|
|
8.6.1 SOUND SPEED AND ATTENUATION |
526 |
|
|
8.6.2 SHEAR WAVE MEASUREMENTS |
529 |
|
|
8.6.3 INDEX OF IMPEDANCE |
532 |
|
|
8.7 SEAFLOOR ROUGHNESS |
534 |
|
|
8.7.1 MEASUREMENT OF SEAFLOOR ROUGHNESS |
535 |
|
|
8.7.2 STATISTICAL CHARACTERIZATION OF SEAFLOOR ROUGHNESS |
537 |
|
|
8.7.3 PREDICTION OF SEAFLOOR ROUGHNESS FROM SEDIMENT PHYSICAL PROPERTIES |
537 |
|
|
8.8 SEAFLOOR HETEROGENEITY |
539 |
|
|
8.8.1 MEASUREMENTS OF SEDIMENT VOLUME HETEROGENEITY |
540 |
|
|
8.8.2 GAS IN SEDIMENTS |
541 |
|
|
8.9 SEAFLOOR IDENTIFICATION AND CHARACTERIZATION BY USE OF SONAR |
543 |
|
|
8.9.1 FEATURE CLUSTERING |
546 |
|
|
8.9.2 IMAGE SEGMENTATION |
548 |
|
|
8.9.3 REFLECTION |
548 |
|
|
8.9.4 SCATTERING STRENGTH |
549 |
|
|
8.9.5 MODEL FITTING TO ECHO TIME SERIES |
554 |
|
|
LIST OF SYMBOLS |
557 |
|
|
REFERENCES |
560 |
|
|
9 - Inverse Methods in Underwater Acoustics |
570 |
|
|
9.1 INTRODUCTION |
570 |
|
|
9.2 SOME BASIC MATHEMATICAL RELATIONSHIPS |
572 |
|
|
9.3 SOURCE LOCALIZATION BY MATCHED FIELD PROCESSING |
573 |
|
|
9.4 GEOACOUSTIC INVERSION |
576 |
|
|
9.4.1 GEOACOUSTIC MODELS |
576 |
|
|
9.4.2 LINEAR INVERSIONS FOR GEOACOUSTIC PROFILES |
578 |
|
|
9.4.3 GEOACOUSTIC INVERSION BY BAYESIAN INFERENCE |
580 |
|
|
9.4.4 BAYESIAN MATCHED FIELD INVERSION |
584 |
|
|
9.4.4.1 Bayesian Matched Field Inversion by Optimization |
584 |
|
|
9.4.4.2 Bayesian Matched Field Inversion by Integration of the a Posteriori Probability Density |
589 |
|
|
9.5 OCEAN ACOUSTIC TOMOGRAPHY |
593 |
|
|
9.5.1 INVERSION OF TRAVEL TIMES |
594 |
|
|
9.5.2 ACOUSTIC THERMOMETRY |
595 |
|
|
9.5.3 ACOUSTIC TOMOGRAPHY IN SHALLOW WATER |
597 |
|
|
REFERENCES |
598 |
|
|
10 - Sonar Systems |
604 |
|
|
10.1 SONAR SYSTEM APPLICATIONS |
605 |
|
|
10.2 SONAR SYSTEM TYPES |
608 |
|
|
10.2.1 TRANSDUCER MATERIALS |
608 |
|
|
10.2.2 PROJECTORS AND HYDROPHONES |
613 |
|
|
10.2.3 PARAMETERS OF PIEZOCERAMICS |
618 |
|
|
10.2.4 TRANSDUCER GEOMETRIES |
623 |
|
|
10.2.4.1 Plates |
624 |
|
|
10.2.4.2 Cylindrical Elements |
624 |
|
|
10.2.4.3 Spherical Elements |
628 |
|
|
10.2.4.4 Tonpilz Transducers |
630 |
|
|
10.2.4.5 Flextensional Transducers |
633 |
|
|
10.2.4.6 Flexural Transducers |
635 |
|
|
10.2.5 ACOUSTIC FIELD QUALITIES OF TRANSDUCERS |
638 |
|
|
10.2.5.1 Single-Element Transducers |
639 |
|
|
10.2.5.1.1 The Pole Concept |
639 |
|
|
10.2.5.1.2 Piston Sources |
643 |
|
|
10.2.5.1.3 Hydrophones |
654 |
|
|
10.2.5.2 Arrays |
661 |
|
|
10.2.5.2.1 Array Types |
662 |
|
|
10.2.5.2.2 Array Qualities |
669 |
|
|
10.2.5.2.3 Towed Arrays |
677 |
|
|
10.3 SINGLE-BEAM ECHO SOUNDERS |
681 |
|
|
10.4 MULTIBEAM ECHO SOUNDERS |
689 |
|
|
10.4.1 MULTIBEAM ECHO SOUNDER STRUCTURE |
696 |
|
|
10.4.1.1 Projector Unit |
697 |
|
|
10.4.1.2 Receiver Unit |
698 |
|
|
10.4.1.3 Sonar Processor Unit |
699 |
|
|
10.4.1.4 Auxiliary Equipment |
701 |
|
|
10.4.2 MULTIBEAM ECHO SOUNDER APPLICATIONS |
702 |
|
|
10.4.2.1 Bathymetry |
702 |
|
|
10.4.2.2 Snippets |
705 |
|
|
10.4.2.3 Side-Scan Data |
705 |
|
|
10.4.3 MULTIBEAM ECHO SOUNDER PERFORMANCE LIMITATIONS |
705 |
|
|
10.5 SIDE-SCAN SONAR |
706 |
|
|
10.5.1 SINGLE-ROW SSS |
706 |
|
|
10.5.2 MULTIROW SSS |
712 |
|
|
10.6 SYNTHETIC APERTURE SONAR |
713 |
|
|
10.7 OTHER SONAR TYPES |
718 |
|
|
10.8 TRANSDUCER CALIBRATION |
723 |
|
|
10.8.1 DEFINITIONS |
723 |
|
|
10.8.2 RECIPROCITY CALIBRATIONS |
725 |
|
|
10.8.3 OTHER CALIBRATION METHODS |
729 |
|
|
10.9 SONAR SYSTEM EXAMPLE CALCULATIONS |
734 |
|
|
10.10 SONAR DESIGN CALCULATIONS |
740 |
|
|
10.10.1 TONPILZ TRANSDUCER AND HYDROPHONE CALCULATIONS |
741 |
|
|
10.10.2 EQUIVALENT CIRCUITS |
745 |
|
|
10.10.3 FINITE-ELEMENT TECHNIQUES |
749 |
|
|
10.11 SYMBOLS AND ABBREVIATIONS |
753 |
|
|
REFERENCES |
755 |
|
|
11 - Signal Processing |
760 |
|
|
11.1 BACKGROUND AND DEFINITIONS |
760 |
|
|
11.1.1 SIGNALS AND NOISE IN UNDERWATER ACOUSTICS |
760 |
|
|
11.1.2 WHAT IS “SIGNAL PROCESSING” AND WHY DO WE DO IT? |
761 |
|
|
11.1.3 STRUCTURE OF THIS CHAPTER |
763 |
|
|
11.1.4 OTHER RESOURCES |
763 |
|
|
11.1.5 MATHEMATICAL NOTATION |
764 |
|
|
11.1.6 LIST OF SYMBOLS AND NOTATION |
764 |
|
|
11.1.7 LIST OF ABBREVIATIONS |
765 |
|
|
11.2 CHARACTERIZING THE SIGNAL AND NOISE |
766 |
|
|
11.2.1 SAMPLING AND QUANTIZING ANALOG SIGNALS |
766 |
|
|
11.2.2 TIME AND FREQUENCY CHARACTERIZATION |
767 |
|
|
11.2.2.1 Signal Consistency: Deterministic and Random Signals |
768 |
|
|
11.2.2.2 Temporal Characterization |
768 |
|
|
11.2.2.3 Spectral Content: The Fourier Transform and Spectral Density |
769 |
|
|
11.2.3 DISCRETE FOURIER TRANSFORM |
772 |
|
|
11.2.4 RANDOM PROCESSES: SPECTRA AND CORRELATION FUNCTIONS |
773 |
|
|
11.2.5 CROSS-SPECTRA AND COHERENCE |
775 |
|
|
11.2.6 CEPSTRUM |
775 |
|
|
11.3 FILTERING |
776 |
|
|
11.3.1 FILTER TYPES |
776 |
|
|
11.3.2 PERFORMANCE METRICS, DESIGN, AND IMPLEMENTATION |
777 |
|
|
11.3.2.1 Filtering Performance Metrics |
777 |
|
|
11.3.2.2 Digital Filter Design and Implementation |
777 |
|
|
11.3.3 BAND-PASS SIGNALS: DIGITAL DOWN-CONVERSION |
781 |
|
|
11.3.4 WINDOWING FOR SIDE-LOBE SUPPRESSION |
781 |
|
|
11.3.5 DATA-DEPENDENT OR ADAPTIVE FILTERING |
784 |
|
|
11.4 DETECTION |
784 |
|
|
11.4.1 PERFORMANCE METRICS, DESIGN, IMPLEMENTATION, AND ANALYSIS PROCEDURE |
786 |
|
|
11.4.1.1 Detection Performance Metrics |
786 |
|
|
11.4.1.2 Required SNR and Detection Threshold |
787 |
|
|
11.4.1.3 Detector Design and Implementation |
788 |
|
|
11.4.1.4 Analysis of Detection Performance |
790 |
|
|
11.4.2 STRUCTURED DESIGN APPROACHES |
791 |
|
|
11.4.3 DETECTING SIGNALS OF KNOWN FORM: CORRELATION PROCESSING |
794 |
|
|
11.4.3.1 Example: Doppler Filter Bank |
794 |
|
|
11.4.3.2 Pulse Compression, Matched Filtering, and the Ambiguity Function |
796 |
|
|
11.4.3.3 Example: LFM Pulse Compression |
797 |
|
|
11.4.3.4 Other Applications in Underwater Acoustics |
798 |
|
|
11.4.4 DETECTING RANDOM OR UNKNOWN SIGNALS: ENERGY DETECTOR |
798 |
|
|
11.4.5 DETECTING UNKNOWN SIGNAL ONSET: PAGE'S TEST |
799 |
|
|
11.4.6 NORMALIZING FOR CONSTANT FALSE ALARM RATE |
801 |
|
|
11.5 ESTIMATION |
803 |
|
|
11.5.1 PERFORMANCE METRICS, DESIGN, IMPLEMENTATION, AND ANALYSIS PROCEDURE |
804 |
|
|
11.5.1.1 Estimation Performance Metrics |
804 |
|
|
11.5.1.2 Estimator Design and Implementation Process |
805 |
|
|
11.5.1.3 Estimator Analysis Procedure and the Cramer-Rao Lower Bound |
805 |
|
|
11.5.2 STRUCTURED DESIGN APPROACHES |
806 |
|
|
11.5.2.1 Maximum Likelihood Estimation |
806 |
|
|
11.5.2.2 Method of Moments Estimation |
808 |
|
|
11.5.2.3 Other Approaches |
809 |
|
|
11.5.3 SPECTROGRAM, PERIODOGRAM, AND POWER SPECTRAL DENSITY ESTIMATION |
809 |
|
|
11.5.3.1 Periodogram for Spectral Density Estimation |
811 |
|
|
11.5.3.2 Zero-Padding the DFT |
814 |
|
|
11.5.4 TIME-DELAY ESTIMATION |
815 |
|
|
11.5.5 BEAMFORMING AND ANGLE OF ARRIVAL ESTIMATION |
818 |
|
|
REFERENCES |
821 |
|
|
12 - Bio- and Fishery Acoustics |
826 |
|
|
12.1 INTRODUCTION |
826 |
|
|
12.2 MARINE LIFE: FROM WHALES TO PLANKTON |
827 |
|
|
12.3 ACOUSTIC SCATTERING BY MARINE LIFE |
828 |
|
|
12.3.1 ZOOPLANKTON SCATTERING |
830 |
|
|
12.3.2 SWIM BLADDER SCATTERING |
832 |
|
|
12.3.3 FISH BODY SCATTERING |
834 |
|
|
12.3.4 LARGE-BODY SCATTERING |
835 |
|
|
12.3.5 MANY-BODY SCATTERING |
838 |
|
|
12.4 ACTIVE IMAGING SYSTEMS |
841 |
|
|
12.4.1 SINGLE-BEAM ECHO SOUNDERS |
841 |
|
|
12.4.2 SIDE-SCAN SONARS |
845 |
|
|
12.4.3 MULTIBEAM ECHO SOUNDERS |
846 |
|
|
12.4.4 COMBINING SENSORS |
849 |
|
|
12.5 MARINE LIFE AND SOUND |
852 |
|
|
12.5.1 GENERAL POINTS |
852 |
|
|
12.5.2 MARINE MAMMALS |
853 |
|
|
12.5.3 FISH, TURTLES, AND INVERTEBRATES |
855 |
|
|
12.6 PASSIVE ACOUSTIC MONITORING |
857 |
|
|
12.7 SELECTED PRACTICAL APPLICATIONS |
860 |
|
|
12.7.1 ACTIVE ACOUSTICS: FISH SURVEY |
860 |
|
|
12.7.2 PASSIVE ACOUSTICS: AMBIENT NOISE MONITORING |
861 |
|
|
12.7.3 ACOUSTIC TELEMETRY: FISH BEHAVIOR |
863 |
|
|
12.8 CONCLUSIONS: FUTURE DEVELOPMENTS |
864 |
|
|
REFERENCES |
866 |
|
|
13 - Finite-Amplitude Waves |
874 |
|
|
13.1 PHYSICS AND NONLINEAR PHENOMENA |
875 |
|
|
13.1.1 HARMONIC DISTORTION |
875 |
|
|
13.1.2 FOCUSED SOUND FIELDS |
878 |
|
|
13.1.3 CAVITATION |
880 |
|
|
13.1.4 ACOUSTIC RADIATION PRESSURE AND ACOUSTIC STREAMING |
882 |
|
|
13.2 NONLINEAR UNDERWATER ACOUSTICS |
883 |
|
|
13.2.1 PARAMETRIC ACOUSTIC TRANSMITTING ARRAYS |
884 |
|
|
13.2.2 PARAMETRIC ACOUSTIC RECEIVING ARRAYS |
889 |
|
|
13.2.3 APPLICATIONS OF THE PARAMETRIC ACOUSTIC ARRAY |
890 |
|
|
13.3 UNDERWATER EXPLOSIONS |
895 |
|
|
13.3.1 THE SHOCK WAVE |
895 |
|
|
13.3.2 THE GAS BUBBLE |
897 |
|
|
13.3.3 OTHER SOURCES OF HIGH-INTENSITY SOUND |
898 |
|
|
13.4 LIST OF SYMBOLS AND ABBREVIATIONS |
901 |
|
|
REFERENCES |
903 |
|
|
14 - Underwater Acoustic Measurements and Their Applications |
906 |
|
|
14.1 INTRODUCTION |
906 |
|
|
14.2 ACOUSTICS AND MARINE RENEWABLE ENERGY DEVELOPMENTS |
907 |
|
|
14.2.1 NOISE DURING THE CONSTRUCTION PHASE |
908 |
|
|
14.2.2 NOISE DURING OPERATION |
910 |
|
|
14.3 UNDERWATER ACOUSTICS IN NUCLEAR-TEST-BAN TREATY MONITORING |
911 |
|
|
14.3.1 THE HYDROACOUSTIC NETWORK OF THE CTBTO |
913 |
|
|
14.3.2 INSTALLATION AND PERFORMANCE OF THE NEWEST IMS HYDROACOUSTIC STATION: HA03, ROBINSON CRUSOE ISLAND, JUAN FERNÁNDEZ ARCHIPEL ... |
914 |
|
|
14.4 CHARACTERIZATION OF NOISE FROM SHIPS |
916 |
|
|
14.4.1 GENERAL CHARACTERIZATION OF NOISE PRODUCED BY SHIPS |
916 |
|
|
14.4.2 NOISE GENERATED BY A PROPULSION SYSTEM |
918 |
|
|
14.4.3 NOISE GENERATED BY A PROPELLER |
919 |
|
|
14.4.4 IDENTIFICATION OF ACOUSTIC WAVES EMITTED BY A MOVING SHIP |
919 |
|
|
14.4.5 SUMMARY |
920 |
|
|
14.5 UNDERWATER SOUNDSCAPES |
921 |
|
|
14.6 UNDERWATER ACOUSTIC COMMUNICATIONS |
925 |
|
|
14.7 UNDERWATER ARCHAEOLOGY |
930 |
|
|
14.7.1 THE WORKING CYCLE OF FIELD MARINE ARCHAEOLOGISTS |
930 |
|
|
14.7.1.1 Large Area Search |
931 |
|
|
14.7.1.2 Local Surveying and Mapping |
932 |
|
|
14.7.1.3 Evolving Trends: A Technological Future for the Exploration of Deep Water Archaeological Sites |
933 |
|
|
14.8 APPLICATIONS OF UNDERWATER ACOUSTICS IN POLAR ENVIRONMENTS |
934 |
|
|
14.8.1 INTRODUCTION |
934 |
|
|
14.8.2 ARCTIC |
935 |
|
|
14.8.3 ANTARCTIC |
938 |
|
|
14.9 TANK EXPERIMENTS |
940 |
|
|
14.9.1 INTRODUCTION |
940 |
|
|
14.9.2 DESCRIPTION OF DIFFERENT CATEGORIES OF TANKS USED FOR UNDERWATER APPLICATIONS |
941 |
|
|
14.9.3 CONCLUSION |
944 |
|
|
14.10 ACOUSTIC POSITIONING AT SEA |
944 |
|
|
14.10.1 LBL POSITIONING DEVELOPMENT |
945 |
|
|
14.10.2 ULTRASHORT BASELINE (USBL) POSITIONING |
946 |
|
|
14.10.3 EFFECTS OF NOISE |
947 |
|
|
14.10.4 IMPROVED CODING |
947 |
|
|
14.10.5 COORDINATION WITH INERTIAL SENSORS |
947 |
|
|
14.11 OCEAN OBSERVING SYSTEMS AND OCEAN OBSERVATORIES, OCEANOGRAPHERS, AND ACOUSTICIANS—A PERSONAL PERSPECTIVE |
948 |
|
|
14.11.1 INTRODUCTION |
948 |
|
|
14.11.2 OCEANOGRAPHERS |
949 |
|
|
14.11.3 ACOUSTICIANS |
950 |
|
|
14.11.4 FUTURE DIRECTIONS |
950 |
|
|
14.12 APPLICATIONS OF UNDERWATER ACOUSTICS TO MILITARY PURPOSES |
951 |
|
|
14.12.1 PASSIVE SONAR |
952 |
|
|
14.12.2 ACTIVE SONAR |
955 |
|
|
REFERENCES |
957 |
|
|
Index |
966 |
|
|
A |
966 |
|
|
B |
967 |
|
|
C |
968 |
|
|
D |
968 |
|
|
E |
969 |
|
|
F |
969 |
|
|
G |
970 |
|
|
H |
970 |
|
|
I |
970 |
|
|
J |
971 |
|
|
K |
971 |
|
|
L |
971 |
|
|
M |
971 |
|
|
N |
972 |
|
|
O |
972 |
|
|
P |
973 |
|
|
Q |
974 |
|
|
R |
974 |
|
|
S |
974 |
|
|
T |
979 |
|
|
U |
980 |
|
|
V |
981 |
|
|
W |
981 |
|
|
Y |
981 |
|
|
Z |
981 |
|