This textbook on Underwater Acoustics has a structure that is more organic than logical. It thereby unifies diverse areas of research, including topics of signal processing, the sonar equation, sources and receivers, scattering and reverberation, wave propagation, propagation models, and inverse problems. It also provides code fragments written in Python which complement the discussion. This is a book written for both beginners and specialists, as well as for biologists, oceanographers, computer engineers, physicists, and mathematicians, and for civilian and naval personnel who are looking for a introductory overview of the topic.
Author(s): Orlando Camargo RodrÃguez
Publisher: Springer
Year: 2023
Language: English
Pages: 224
City: Cham
Preface
Contents
1 A Bit of History
2 The Ocean
2.1 Introduction
2.2 Typical Scales
2.3 The Deep Ocean
2.4 The Shallow Ocean
3 Signals and Noise
3.1 Introduction
3.2 Noise
3.2.1 White Noise
3.2.2 Correlated Noise
3.3 Signals
3.3.1 The Unit Impulse
3.3.2 The Rectangular Signal
3.3.3 Tones
3.3.4 Frequency Modulation
3.3.5 M-sequences
3.3.6 Wavelets
3.3.7 The Analytic Signal
3.3.8 Signal Filtering
3.3.9 Signal Correlation
3.4 The Impulse Response
3.5 Fourier Synthesis
3.6 The Signal-to-Noise Ratio
3.6.1 Definition
3.6.2 Signal Contamination with Noise
3.6.3 Estimating the SNR
3.7 Detection Theory
3.8 Cepstrum Analysis
4 Waves in Boundless Media
4.1 Introduction
4.2 The Wave Equation
4.3 Analytical Solutions
4.3.1 Plane Waves
4.3.2 Cylindrical Waves
4.3.3 Spherical Waves
4.3.4 Sommerfeld's Identity
4.4 Phase Velocity, Group Velocity
4.5 Attenuation
4.6 The Doppler Effect
5 Waves in Bounded Media
5.1 Introduction
5.2 The Navier–Stokes Equation
5.3 Acoustic Impedance
5.4 Wave Dispersion
5.5 Wave Refraction
5.6 The Speed of Sound
5.7 Wave Reflection
5.8 Beam Displacement
5.9 Final Remarks
6 The SONAR Equation
6.1 Introduction
6.2 The Passive SONAR Equation
6.3 The Active SONAR Equation
6.4 The Signal Excess
6.5 The Source Sound Level
6.6 The Transmission Loss
6.7 The Noise Level
6.8 The Directivity Index
6.9 The Target Strength
6.10 The Reverberation Level
6.11 Examples
7 Arrays, Transducers and Vector Sensors
7.1 Introduction
7.2 Array with Two Transducers
7.3 Array with Several Transducers
7.4 Linear Array
7.5 Disk Array
7.6 Frequency Response
7.7 Vector Sensors
8 Propagation Models
8.1 Introduction
8.2 Ray Tracing
8.2.1 Ray Trajectories
8.2.2 The Hamiltonian
8.2.3 Geodesics
8.2.4 Ray Amplitudes
8.2.5 Ray Interference
8.2.6 Source Directivity
8.3 Normal Modes
8.3.1 The Isovelocity Waveguide
8.3.2 The Pekeris Waveguide
8.3.3 Airy Phase
8.3.4 Adiabatic Propagation
8.3.5 Modes and the Reflection Coefficient
8.3.6 The Waveguide Invariant
8.3.7 Numerical Calculation of Modes
8.3.8 Source Directivity
8.4 The WKBJ Approximation
8.5 Fast-Field Models
8.6 The Parabolic Equation
9 Scattering and Reverberation
9.1 Introduction
9.2 Lambert's Model
9.3 Surface Scattering
9.4 Surface Backscattering
9.5 Bottom Scattering
9.6 Multibeam and Sidescan Sonars
9.7 Boundary Reverberation
9.8 Example
10 Inverse Problems
10.1 Introduction
10.2 Source Localization
10.2.1 Bearing Estimation
10.2.2 Range and Depth Estimation
10.3 Geoacoustics
10.4 Tomography
10.4.1 Matched-Field Tomography
10.4.2 Travel-Time Tomography
Appendix A Sea Surface Roughness
A.1 Introduction
A.2 Spectra of Wind-Driven Sea Surface Waves
A.2.1 Wave Height and Speed
A.2.2 Frequency to Wavenumber Conversion
A.2.3 Angular Spreading
A.3 Swells
Appendix B Solving a System of Linear Equations
Appendix References
