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| Preface | |
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| About the Author | |
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| Introduction | |
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| Sound | |
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| Wave motion | |
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| Sound pressure | |
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| Reference intensity | |
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| Source level | |
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| Radiated power | |
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| Limitations to sonar power | |
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| Cavitation | |
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| Interaction | |
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| Changes to arrays | |
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| Projector sensitivity | |
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| Hydrophone sensitivity | |
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| Spectrum level | |
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| Sound in air and in sea water | |
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| Problems | |
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| Arrays | |
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| Need for projector arrays | |
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| Need for hydrophone arrays | |
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| Beam patterns | |
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| Directivity of a dipole | |
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| The general line array | |
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| Line array: beam pattern vs. steer angle | |
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| Broadside array: length and spacing | |
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| Beam pattern for a continuous line | |
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| Shading | |
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| Shaded arrays: transmit source levels | |
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| Directivity index | |
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| DI of a simple dipole | |
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| DI of a line array | |
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| DI of a planar array | |
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| DI of a cylindrical array | |
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| DI formulae based for simple arrays | |
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| Conformal arrays | |
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| Spherical arrays | |
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| Volumetric arrays | |
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| Beamformers | |
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| Domes and arrays | |
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| Problems | |
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| Propagation of Sound in the Sea | |
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| Propagation loss | |
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| Losses | |
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| Spreading losses | |
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| Absorption losses | |
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| Spherical spreading and absorption | |
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| Propagation in the real ocean | |
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| The speed of sound | |
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| Sound speed profiles | |
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| Deep sound channel | |
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| Reliable acoustic path | |
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| Surface duct propagation | |
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| Convergence zone propagation | |
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| Bottom bounce propagation | |
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| Propagation loss models | |
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| Ray theory and the Hodgson model | |
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| Hodgson example | |
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| Performance prediction | |
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| Multipath propagation | |
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| Problems | |
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| Target Strength | |
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| Definition | |
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| Formulae | |
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| Measurement | |
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| Dependence on pulse type and duration | |
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| TS of a sphere | |
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| TS of some simple shapes | |
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| TS of small targets | |
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| Mine target strength | |
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| Torpedo target strength | |
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| Submarine echoes | |
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| Beam aspect target strength | |
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| Bow aspect target strength | |
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| Submarine target strengths | |
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| Towed arrays | |
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| Target strength reduction | |
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| Practical values | |
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| Problems | |
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| Noise in Sonar Systems | |
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| Sources of noise | |
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| Thermal noise | |
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| Noise from the sea | |
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| Noise from a vessel | |
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| The sonar environment | |
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| Self-noise | |
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| Electrical noise | |
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| Machinery noise | |
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| Flow noise | |
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| Propeller noise | |
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| Variation with speed | |
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| Variation with frequency | |
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| Directivity | |
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| Self-noise and radiated noise | |
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| Addition of noise levels | |
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| Receiver noise factor | |
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| Noise factor of a sonar | |
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| Acceptable receiver noise level | |
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| Alternative calculation | |
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| Practical values | |
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| Problems | |
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| Reverberation | |
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| Sources of reverberation | |
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| Scattering and reflection | |
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| Boundary roughness | |
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| Classes of reverberation | |
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| Backscattering strength | |
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| Reverberation target strength | |
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| Volume reverberation | |
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| Boundary reverberation | |
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| Scattering layers | |
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| Volume scattering strength | |
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| Sea surface scattering strength | |
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| Bottom scattering strength | |
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| Variation with frequency | |
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| Reverberation under ice | |
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| Problems | |
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| The Sonar Equations | |
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| What are they? | |
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| What are their uses? | |
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| The basic sonar equation | |
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| The basic passive equation | |
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| The basic active equation | |
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| Detection threshold and detection index | |
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| Receiver operating characteristics | |
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| ROC curves | |
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| Problems | |
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| Passive Sonar | |
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| Radiated noise | |
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| Radiated noise: source level | |
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| Nature of radiated noise | |
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| Practical values | |
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| Broadband and narrowband | |
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| Normalization | |
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| A Note on Swaths | |
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| Passive arrays | |
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| Passive aural | |
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| Passive displays | |
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| Formulae for detection threshold | |
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| Broadband square law detector | |
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| Broadband cross-correlator detector | |
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| Narrowband processor | |
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| Narrowband amplitude detector processor | |
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| Worked examples | |
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| Passive ranging | |
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| Triangulation | |
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| Vertical direct passive ranging | |
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| Horizontal direct passive ranging | |
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| Towed arrays | |
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| Bearing ambiguity | |
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| Self-noise | |
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| Problems | |
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| Active Sonar | |
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| Range, pings and doppler shift | |
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| Pulse types | |
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| CW processing | |
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| FM processing | |
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| Active sonar equations | |
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| Reverberation index | |
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| FM pulses | |
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| CW pulses | |
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| Reverberation rejection by CW pulses | |
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| Reverberation and Target Echoes in the main lobe | |
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| Reverberation and Target Echoes in the sidelobes | |
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| Practical reverberation envelopes | |
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| Full- and half-beam processing | |
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| Beamforming | |
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| FM phase binning process | |
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| CW processing | |
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| Large aperture array | |
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| Detection performance | |
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| Noise and reverberation-limited detection ranges | |
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| Ambiguity diagrams | |
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| Very long pulses | |
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| Operational degradation factor | |
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| Active displays | |
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| Unified detection and classification | |
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| Bandwidth | |
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| Beamwidth | |
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| CADAC | |
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| Levels of CADAC | |
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| CADAC and pulse features | |
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| Statistical analysis | |
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| Amplitude profiles | |
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| Multipath affects classification | |
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| Simple multipath example | |
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| Deep water: source and target in duct | |
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| Deep water: source and target below duct | |
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| Shallow water: source and target mid-water | |
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| Problems | |
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| Echo Sounding and Side Scan Sonars | |
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| Common features | |
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| Echo sounders | |
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| Echo sounder: design example | |
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| Side scan sonar | |
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| Side scan sonar: design example | |
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| Problem | |
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| Mine Hunting Sonars | |
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| Overview | |
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| Two broad classes of mine | |
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| Backgrounds to mine detection | |
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| Range and bearing resolution | |
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| Design of a mine hunting sonar | |
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| The threats | |
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| Design example | |
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| Performance | |
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| Classification | |
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| Mine avoidance | |
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| Mine avoidance sonars | |
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| Problems | |
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| Intercept and Communications Sonars | |
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| Intercept sonars | |
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| Communications sonars | |
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| Function of an intercept sonar | |
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| Intercept sonar equation | |
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| Worked examples | |
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| Reduction in the probability of intercept | |
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| Reduction in the probability of exploitation | |
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| Effectiveness of intercept sonars | |
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| Communications sonars | |
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| Communications sonar equation | |
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| Examples of communications sonars | |
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| Problems | |
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| Active Sonar Design | |
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| Introduction | |
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| Submarine detection | |
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| Hull-mounted surface ship sonar | |
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| Representative hull-mounted design | |
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| Longer ranges | |
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| Towed transmitters and towed array receivers | |
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| Representative design | |
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| Low frequency active: beware! | |
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| Torpedo detection | |
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| Conclusion | |
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| Solutions to Problems | |
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| Index | |