Sonar and Underwater Acoustics brings together all the concepts necessary for designers and users of sonar systems. Unlike other books on this subject, which are often too specialized, this book is accessible to a wider audience. The first part focuses on the acoustic environment, antenna structures, and electric acoustic interface. The latter provides knowledge required to design, as well as the development and implementation of chain processes for an active sonar from the conditioning input to output processing. The reader will find a comprehensive range of all problems encountered in underwater acoustics for a sonar application, from physical phenomena governing the environment and the corresponding constraints, through to the technical definition of transducers and antennas, and the types of signal processing involved. In one section, measures in underwater acoustics are also proposed.

Table of Contents:
Preface ix PART 1. THE MARINE ENVIRONMENT 1 Part 1. Introduction 3 Chapter 1. Problematics 5 1.1. History 5 1.2. Underwater acoustics 7 1.3. Applications 9 1.4. Comparison with radar 10 1.5. Submarine detection and warfare 11 1.6. Submarine detection 11 1.7. Submarine detection: a veritable challenge 12 1.8. Overcoming the effects of the ocean 13 1.9. Sonar and information processing 16 Chapter 2. Sound Propagation in the Marine Environment 19 2.1. General points 19 2.2. Characteristics of the marine environment 19 2.3. Models used 22 2.4. Propagation phenomena 28 2.5. Application examples 33 Chapter 3. Noises and Reverberation 41 3.1. Classification of ambient noises 41 3.2. Analysis of noise sources 45 3.3. Wenz’ model of sea noise 51 3.4. Directivity of sea noise 52 3.5. Reverberation 55 Chapter 4. Radiated and Inherent Noises 65 4.1. Radiated noise 65 Chapter 5. Transmission of the Acoustic Signal: Sonar Equations 79 5.1. Introduction 79 5.2. Detection contrast and detection index 80 5.3. Transmission equation 81 5.4. Equation of passive sonar 88 5.5. Equation of active sonar 89 PART 2. ACOUSTIC-ELECTRIC INTERFACE ANTENNA STRUCTURES 93 Part 2. Introduction 95 Chapter 6. Electric-acoustic and Acoustic-electric Transformations 97 6.1. Transducers and hydrophones 97 Chapter 7. Performance and Structures of Acoustic Antennas 113 7.1. Antennas and radiation 113 7.2. Structures of sources and antennas 189 Chapter 8. Electronic Transducer-hydrophone Adaptation 211 8.1. Hydrophones 211 8.2. Transducers 243 Chapter 9. Electro-mechano-acoustic Analogies 269 9.1. Methods of studying transducers and hydrophones 269 9.2. Mechanic-electric equivalence 270 9.3. Electric-acoustic equivalence 275 9.4. Finite element method (FEM) 320 PART 3. PROCESSING CHAIN OF ACTIVE SONAR 323 Part 3. Introduction 325 Chapter 10. Selection Criteria in Active Processing 327 10.1. Selection criteria related to propagation 327 10.2. Selection criteria relative to noise 331 10.3. Selection criteria related to reverberation 332 10.4. Selection criteria related to emission power 333 10.5. Selection criteria related to the antenna 335 10.6. Selection criteria for the operating frequency 336 10.7. Selection criteria related to operational considerations 337 10.8. Selection criteria related to the nature of targets 337 Chapter 11. Processing Chain in Active Sonar 341 11.1. General points 341 11.2. Emission 341 11.3. Reception 345 Chapter 12. Basic Theoretical Notions in Active Processing 459 12.1. The Doppler effect 459 12.2. The Doppler effect in active sonar conditions 464 12.3. Treatment of the signal 485 12.4. Choice of an emission signal under active sonar conditions 503 Chapter 13. Measurement in Underwater Acoustics 525 13.1. Introduction 525 13.2. Wave train method 531 13.3. Precautions before measuring 539 13.4. Acoustic measurements and calibrations of transducers 542 13.5. Notion of uncertainty estimation and of maximum tolerated difference 551 13.6. Other types of measurements in underwater acoustics 553 APPENDICES 555 Appendix 1. Logarithmic Scales 557 Appendix 2. Equation of Sound in Fluids 563 Appendix 3. Piezoelectricity Fundamentals 571 Appendix 4. Vector Analysis ?Ï?nFundamentals 579 Appendix 5. Reciprocity Theorem 593 Appendix 6. Concrete Example of Uncertainty Estimation Based on the Reciprocity Calibration Method 601 Bibliography 619 Index 623