Digital Sonar Design in Underwater Acoustics: Principles and Applications

cover......Page 1
Front matter......Page 2
Title Page
......Page 4
Copyright Page 
......Page 5
Preface......Page 7
Table of Contents
......Page 9
Abbreviations
......Page 18
1.1 Evolution of Digital Sonar Systems......Page 23
1.2 Main Features of Digital Sonar......Page 27
1.3 Today and Tomorrow of Digital Sonar......Page 32
References......Page 37
2.1 Digital Conversion of Analogue Signal: Quantization andSampling......Page 40
2.1.1 Signal Sampling......Page 42
2.1.2 Signal Quantization......Page 47
2.1.3 Signal Companding......Page 49
2.1.4 I - LI Modulation......Page 51
2.2.1 Linear Digital Filtering......Page 53
2.2.2 Transfer Function of a Linear System......Page 55
2.2.3 Classification of Digital Filters......Page 57
2.2.4 Cascade of Digital Filters......Page 60
2.2.5 Examples of Digital Filters......Page 61
2.3.1 Fourier Transform of Signal......Page 62
2.3.3 Discrete Fourier Transform......Page 64
2.3.4 Digital Feature of Signal Represented by Discrete Samples......Page 66
2.3.5 Algorithm of Fast Fourier Transform......Page 68
2.3.6 Calculation of DFT for Real Value DataReduction factor4.08.021.364.0113.8204.8In......Page 71
2.4.1 Local Average Filtering......Page 72
2.4.2 Median Value Filtering......Page 75
2.4.3 Threshold Filtering and Truncate Filtering......Page 77
2.5.1 Definition of Digital Images......Page 79
2.5.2 2D Fourier Transform......Page 80
2.5.3 2D Cosine Discrere Transforms......Page 81
2.5.4 Typical Image Processing Techniques......Page 83
2.5.5 Time/Bearing Display in Digital Sonar......Page 86
2.6.1 Fractal Transform......Page 88
2.6.2 Wavelet Transform......Page 93
References......Page 98
3.1 Some Basic Results from Probability Theory and MathematicalStatistics......Page 101
3.1.1 Basic Definition of Probability......Page 102
3.1.2 Conditional Probability......Page 105
3.1.3 Random Variable and Distribution Function......Page 106
3.1.4 Digital Characteristics of Random Variables......Page 109
3.1.5 Large Number Law and Central Limit Theorem......Page 112
3.1.6 Random Process (Stochastic Process)......Page 114
3.2 Introduction to the Basic Concepts of Information Theory......Page 116
3.2.1 Information and Entropy......Page 117
3.2.2 The Coding Theorem of a Discrete Information Source......Page 123
3.3.1 Basic Concepts of Statistical Hypothesis Tests......Page 126
3.3.2 Optimum Detection Criterion......Page 128
3.3.3 N-P Test......Page 129
3.3.4 Multiple Observations......Page 133
3.3.5 Wald Sequential Test......Page 135
3.4.1 Basic Relation of Input / Output of a Linear System forStationary Random Signal......Page 136
3.4.2 Wiener Filtering......Page 139
3.4.3 Matched Filter......Page 142
3.4.4 Adaptive Filtering......Page 146
3.5 Kalman Filtering for Non-stationary Digital Signal......Page 152
3.5.1 Kalman Filtering of a One-Dimensional Observation Model......Page 153
3.5.2 Kalman Filtering o/Multiple Channels......Page 156
3.6.1 Test of Station arin ess and Ergodicness of a Random Signal......Page 158
3.6.2 Basic Requirements for a Statistic......Page 159
3.6.3 Some Estimates Used Frequently in Sonar Design......Page 160
3.6.4 Cramer-Rao Low Bound......Page 162
3.6.5 Example (Mean Value Estimate)......Page 164
3.6.6 Model-Free Estimates......Page 165
References......Page 167
4.1 Determination of Sonar System Specifications......Page 170
4.1.1 Category of Sonar......Page 171
4.1.2 Relationship between Tactical and Technical Specifications......Page 173
4.1.3.1 Sound Pressure and Sound Power......Page 178
4.1.3.2 Source Level and Spectrum Level......Page 179
4.1.4 Basic Concepts of Sonar Specifications......Page 185
4.1.3.3 Detection Index......Page 182
4.1.3.4 Accuracy of Parameter Estimation: Origin Moment and Center moment......Page 183
4.1.3.6 Reliability Concept......Page 184
4.2.1 Parameters of the Sonar Equation......Page 187
4.2.2 Active Sonar Equation......Page 188
4.2.3 Passive Sonar Qquation......Page 190
4.2.4 Calculation of the Sonar Ranging Distance......Page 191
4.3.1 Main Source of Ambient Noise in the Ocean......Page 194
4.3.2 Frequency spectrum of ambient noise......Page 195
4.3.3 Minimum Ambient Noise......Page 196
4.3.4 Homogeneous and Isotropic Noise Fields......Page 197
4.3.5 Cylindrical and Spherical Model of Ambient Noise......Page 200
4.3.6 Vertical Directivity of Ambient Noise......Page 201
4.4.1 Sources of Radiated Noise......Page 202
4.4.2 Radiated Noise from Submarines......Page 204
4.4.3 Radiated Noise of Surface Ships......Page 206
4.4.5 Self-noise of Vessels......Page 207
4.4.5.1 Platform Noise Received by Hull-mounted SonarThe......Page 208
4.4.5.2 Platform Noise Received by a Towed Array or Towed Body......Page 209
4.4.6 Auto-correlation Function of Target Noise......Page 210
4.5.2 Short Distance Reverberation Theory......Page 212
4.5.3.2 Boundary Reverberation Level......Page 214
4.5.4 Relationship between Reverberation Strength and ImpulseDuration......Page 216
4.5.5 Statistical Characteristics of Reverberations......Page 217
4.6.1 Sound Wave and Vibration......Page 221
4.6.2 Velocity of Sound in the Sea: Sound Speed Profile......Page 222
4.6.3 Wave and Ray Theories of Underwater Sound Fields......Page 226
4.6.4 Transmission Loss......Page 231
4.6.5 Sound Absorption in Sea Water......Page 232
4.6.6 Upper Boundary of Acoustic Channel: the Sea Surface andIts Acoustic Characteristics......Page 233
4.6.8 Use of Propagation Characteristics in Sonar Design......Page 235
4.6.9 Average Structure of a Sound Field in Shallow Water......Page 238
4.6.10 Use of Transmission Loss in Sonar Ranging DistancePrediction......Page 240
4.7.1 Directivity Function (Beam Pattern)......Page 245
4.7.2 Conventional Beamforming......Page 249
4.7.3 Equal-Spaced Line Array......Page 251
4.7.4 Uniformly Distributed Discrete Circle Array......Page 257
4.7.5 Circle Array Ba.lJling and Arc Array......Page 261
4.7.6 Product Theorem of Directivity Function of a Line Array......Page 263
4.7.7 Weighting of an Array......Page 266
4.7.8 General Expression of Directivity Function......Page 272
4.7.9 Continuous Distributed Array......Page 277
4.8 Calculation of Sonar System Gain......Page 278
4.8.1 Spatial Gain of Sonar System......Page 279
4.8.2 Calculation of Time Processing Gain of Passive Sonar......Page 280
4.8.3 Calculation of Time Processing Gain of Active Sonar......Page 286
4.9.1 Relationship between Sonar System Gain and Input signalto-noise Ratio......Page 289
4.9.2 Gain Loss at the Interface of a Hydrophone and an A / DConverter......Page 290
4.9.3 Interface Loss Due to Time Integration......Page 291
4.10 Explosive Source of Underwater Sound......Page 292
4.10.1 Main Characteristics of Explosive Sources of UnderwaterSound......Page 293
4.10.2 Measurement of Transmission Loss by Using ExplosiveSource......Page 296
References......Page 297
5.1 System Architecture of Digital Sonar......Page 304
5.1.1 Parallel Operation and Sequential Operation......Page 305
5.1.2 Differences in Beamforming in Time Domain and FrequencyDomain......Page 306
5.1.4 Real Time Data Display of the Sonar System......Page 310
5.2 Parameter Selection of Programmable Digital Sonar......Page 311
5.3 Pre-processing and FIR filtering......Page 317
5.3.1 Anti-aliazing Filtering......Page 318
5.3.2 A / D Conversion......Page 319
5.3.3 AGC and A / D Converter......Page 320
5.3.4 FIRfiltering......Page 322
5.4.1 Digital Beamforming Using SRAM......Page 326
5.4.2 Optimum Spatial Filter......Page 330
5.5 Target Characteristic Analysis: LOFAR, DEMON andAdaptive Line Enhancer......Page 336
5.5.1.1 Detection of Single Frequency Signal in Noise Background......Page 337
5.5.1.2 General Concept of LOFAR and DEMON......Page 338
5.5.1.3 Examples of LOFAR and DEMON Analysis......Page 340
5.5.2 Adaptive Line Enhancing......Page 343
5.5.3 Combined Architecture of ANC and ALE......Page 347
5.6.1 Square Detection and Absolute Value Detection......Page 351
5.6.2 A Method of Stationarity for Non-stationary Data......Page 353
5.6.3 Basic Technique of Wild Value Filtering......Page 355
5.6.4 Wild Value Filtering/or Two-Dimensional Time/ Bearing Data......Page 358
5.7 Display and Control: High Resolution Gray Scale Displayand Background Equalization......Page 359
5.7.1 Main Function of the Display / Control System......Page 360
5.7.2 Applications of Human / Machine Interface Theory......Page 361
5.7.3 Use of Color in Sonar Display......Page 362
5.7.4 Gray Scale Conversion......Page 363
5.7.5 Background Equalization......Page 366
5.8 Reliability Design of Digital Sonar......Page 368
5.8.2 Brief Introduction to Reliability Engineering......Page 369
5.8.3 Hardware Reliability......Page 370
5.8.5 Technical Means of Hardware Reliability Design......Page 377
5.8.6 Failure Self Test......Page 379
5.9.1 Basic Concept of Data Fusion......Page 380
5.9.2 Optimum Linear Data Fusion......Page 382
5.9.4 Joint Detection and Estimation Problems......Page 388
References......Page 393
6.1 Precise Bearing for Target......Page 398
6.1.1 Concept of the Bearing Accuracy of Sonar......Page 399
6.1.2 Optimum Precise Bearing of Line Array and Circle Array......Page 402
6.1.3 Implementation of Precise Bearing......Page 405
6.1.4 Example of Realization of Precise Bearing Function inDigital Sonar......Page 410
6.1.5 Method/or Improving Bearing Accuracy......Page 414
6.2.1 Tracking Algorithm of Passive Sonar......Page 417
6.2.1.1 Fully Automatic Tracking......Page 418
6.2.1.2 Semi-automatic Tracking......Page 420
6.2.2 Multi-target Resolution......Page 423
6.2.3 Results of System Simulation......Page 424
6.2.4 Method for Increasing the Resolution Ability of MultipleTargets......Page 428
6.3 Moving Target Analysis: Pre-set Tracking......Page 432
6.3.1 Concept of TMA......Page 433
6.3.2 Pre-setting Tracking......Page 434
6.3.3 TMA Research......Page 437
6.4 Fast Moving Target Tracking: Torpedo Alarming......Page 439
6.4.1 Possibility of Torpedo Alarming......Page 440
6.4.2 Double Check Decision Strategy in Torpedo Alarming......Page 441
6.4.3 Target Traces Extraction Technique......Page 443
6.4.4 Example of System Simulation......Page 445
6.5.1 Principle of Three-Point Ranging......Page 446
6.5.2 Four-Point Passive Ranging......Page 449
6.5.3 Analysis of Passive Ranging Accuracy......Page 450
6.5.4 Realization of Passive Ranging......Page 454
6.6 Target Classification and Recognition......Page 455
6.6.1 Basic Requirement of Target Noise Classification......Page 456
6.6.2 Concept of Artificial Neural Network......Page 457
6.6.3 Simplified Expert System......Page 459
6.6.4 An Example of an Expert System Based on NearestNeighborhood Criteria......Page 460
6.7 Active Sonar Signal Capture and Analysis......Page 465
6.7.1 Theoretical Basis of Active Sonar Signal Capture......Page 466
6.7.2 A Combined TIme/Frequency Domain Signal Capture Technique......Page 467
6.7.3 Signal Feature Extraction of Active Sonar Signal......Page 472
6.8 Underwater Acoustic Communication and AdaptiveEqualization of Underwater Acoustic Channel......Page 474
6.8.1 Introduction of Underwater Acoustic Communication......Page 475
6.8.2 Coding and Decoding......Page 477
6.8.3 Frequency Spread Technique......Page 480
6.8.4 Equalization of Underwater Acoustic Channel......Page 482
6.9 Introduction of Multistatic Sonar......Page 485
6.9.1 General Description of Multistatic Sonar Problem......Page 486
6.9.2 Basic Formula for Calculating Detection Range in MultistaticSonar......Page 487
6.9.3 Realization of Bistatic Sonar Function by Using MonostaticSonar......Page 489
References......Page 490
7.1 General Concept of System Simulation......Page 498
7.1.1 Brief Introduction of System Simulation Technique......Page 499
7.1.2 Development of Modern System Simulation Technique......Page 500
7.2.1 Method/or Generating a Random Number......Page 501
7.2.2 Basic Time Series in Digital System Simulation......Page 504
7.3.1 Simulation of the Sonar Environment Field......Page 512
Signal Simulation......Page 513
Multiple Independent Noise Simulation......Page 514
Simulation of Reverberation......Page 515
Digital Filtering......Page 516
Beamforming......Page 517
Iterative Algorithm of Adaptive Noise Canceling (ANC)......Page 520
7.3.3 Simulation of Post Processing......Page 521
7.4 Design of Sonar Signal Simulator......Page 522
7.4.1 General Concept of Sonar Simulator......Page 523
7.4.2 Design Principle of General Purpose Sonar Simulator......Page 524
7.4.3 Algorithm for Generating Infinite Non-cyclic Random Number......Page 526
7.4.4 Generating of Array Signals......Page 528
7.4.5 An Application Example of Sonar Simulator Design......Page 531
References......Page 533
8.1 Concept of Model-Based Sonar......Page 535
8.1.1 Basic Concept of Model-Based Sonar......Page 536
8.1.2 Robust Signal Processing......Page 538
8.1.3 Signal Processing System of Model-Based Sonar......Page 539
8.1.4 Matched Field Filtering......Page 540
8.2 Linear Towed Array Sonar......Page 541
8.2.1 Brief History of Linear Towed Array Sonar......Page 542
8.2.2 General Concept of Towed Array Sonar......Page 543
8.2.3 Status of a Tow Cable under the Sea......Page 545
8.2.4 Shape Distortion ofTowedArray and Its Effect on Beamforming......Page 548
8.2.5.1 Bearing Ambiguity Problem......Page 551
8.2.5.2 Flow Noise of Towed Array......Page 553
8.2.5.3 Relationship between Cable Length, Vessel Speed and Cable Depth......Page 554
8.2.5.5 Tow Ship Noise Canceling......Page 557
8.2.6 Examples of Towed Array Sonar......Page 560
8.3.1 General Concept of Flank Array Sonar......Page 561
8.3.2 Adaptive Canceling of Self Noise......Page 562
8.3.3 Vibration Isolation of Hydrophone and Acoustic DampingMaterials......Page 566
8.3.4 Beamforming of Multiple Elements with Different SNR......Page 567
8.3.5 System Configuration of Flank Array Sonar......Page 568
8.3.6 Example of Typical Flank Array Sonar......Page 569
8.4 Fixed Array Sonar......Page 570
8.4.2 Outline of Shore-Based Sonar Station......Page 571
8.4.3.1 Underwater Wired Signal Transmission......Page 573
8.4.3.2 Reliability of Underwater Equipment......Page 576
8.5 Synthetic Aperture SonarSAS......Page 577
8.5.1 Brief History of SASRadar......Page 578
8.5.2 Basic Principle of SAS......Page 579
8.5.2.1 Resolution Ability of Along-Track and Cross-Track......Page 581
8.5.2.2 Resolution Invariant Principle of SAS......Page 582
8.5.2.3 Minimum Separable Range on Sea Bottom......Page 583
8.5.3 Calculation of Directivity Function of Passive SAS......Page 584
8.5.4 Basic Algorithm of Active SAS......Page 586
8.5.5 An Experimental SAS Prototype......Page 587
8.6.1 Basic Concept of NCW......Page 591
8.6.2 Theory of Complexity System......Page 593
Untitled......Page 594
T-AGOS Surveillance Vessell1......Page 595
Transmission Format ofInformation......Page 596
Underwater Monitoring Network......Page 597
8.7.1 Basic Design Principle of DDS......Page 598
Operating Frequency......Page 599
Beamwidth of Receiver......Page 600
References......Page 601
9 Software and Hardware Support and PerformanceEvaluation in Digital Sonar Design......Page 610
9.1.1 Several Frequently Used Commands in Signal Processing......Page 611
9.1.2 Examples......Page 612
Tool Boxes......Page 614
Self-Defined Function......Page 615
Make a Good Program Flow Chart......Page 616
Decompose a Complicated Problem to Several Relative Simple Problems......Page 617
Testing of Compiled Program......Page 618
9.3.1 Concept of the General Purpose DSP Chip......Page 619
9.3.2 Main Specifications of DSP Chips......Page 620
9.3.4 System Integration......Page 621
9.4.1 Evaluation Procedure of Digital Sonar......Page 622
9.4.2 Step by Step Testing in a Laboratory of a Digital Sonar System......Page 624
Pre-processing......Page 625
Signal Processing Module......Page 627
9.4.3 Wet End Testing of the Sonar System in a Laboratory......Page 628
9.5 Tactical and Technical Performance Evaluation of DigitalSonar: Comparison of Results of Laboratory Testing, LakeTesting and Experiment at Sea......Page 629
9.5.1 From Sonar Design to Experiments at Sea......Page 630
9.5.2 Measurement of Source Level and Sound Pressure Index......Page 631
9.5.3 Measurement of Target Strength and Underwater SignalChannel......Page 635
9.5.4 Calibration of Sonar Specification in Terms of the Result ofExperiments at Sea......Page 638
Chebychev Inequality......Page 641
Proposition of Small Probability Event......Page 642
9.5.6 Central Moment and Original Moment......Page 644
9.5.7 Sea State Description and Some Results of Sonar RangingPrediction......Page 647
References......Page 649
Index......Page 652