This section addresses those attributes, which are common to broad classes of sensor system.

For example, the external environment dramatically affects the performance of all sensor systems.

Similarly, the ability to perform critical functions such as detection or tracking, can be related to certain universal sensor characteristics in an unambiguous fashion. Among these common attributes are the characteristics of observable signals, the effects of propagation through the environment, and the functions desired to be performed.

Other than their use as examples, specific sensor technologies are not discussed until Part II. Specifically, this section describes a set of tools that can be used by the analyst to predict and compare the performance of any kinds of sensor systems. Use of these tools permits apples to apples trade studies to be made between sensors with little or no physical similarity.

In addition, it will become apparent that even after a detailed discussion of radar or sonar components, integration, and operation, the student will be unable to predict the performance of any radar or sonar until after he has learned how to obtain and incorporate the results of detection theory, estimation theory, and propagation theory, among others.

This material is presented first in the hopes of instilling a recognition that sensors can be studied as a unified topic.

Covered in this complete sensor system guide:

CHAPTER 1. SIGNATURES, OBSERVABLES, & PROPAGATORS 3

  • Sensors, Transducers, and Detectors 3
  • Observables 4
  • Signatures and Propagators 5
  • References 11
  • Problems 12

CHAPTER 2. PROPAGATION OF ELECTROMAGNETIC RADIATION. I.
– FUNDAMENTAL EFFECTS 13

  • What is Electromagnetic Radiation 13
  • Attenuation of Electromagnetic Radiation in Bulk Materials 20
  • Reflection and Refraction 23
  • Interference 28
  • Huygens’ Principle and Diffraction 30
  • Mie Scattering 35
  • References 37
  • Problems 38

CHAPTER 3. PROPAGATION OF ELECTROMAGNETIC RADIATION. II.
– WEATHER EFFECTS 39

  • Introduction 39
  • Structure of the Atmosphere 45
  • Molecular Absorption 56
  • Aerosol Scattering 67
  • Hydrometeors – Fogs and Clouds 71
  • Hydrometeors – Precipitation 85
  • Statistics of Weather Effects 89
  • References 100
  • Problems 104

CHAPTER 4. PROPAGATION OF ELECTROMAGNETIC RADIATION. III.
– REFRACTIVE EFFECTS 107

  • Horizon Extension 107
  • Ducting and Mirages 114
  • Atmospheric Turbulence 128
  • Ionospheric Effects 148
  • References 154
  • Problems 156

CHAPTER 5. PROPAGATION OF ELECTROMAGNETIC RADIATION IV.
– OTHER ATMOSPHERIC AND UNDERWATER EFFECTS 159

  • Contrast Transmission 159
  • Smoke, Dust, and Battlefield Obscurants 162
  • Pasquill Stability and Atmospheric Diffusion 168
  • Transmission Through Stratified Media 176
  • Multipath 179
  • Terrain Masking 183
  • Underwater Propagation 187
  • References 190
  • Problems 192

CHAPTER 6. PROPAGATION OF ACOUSTIC RADIATION 195

  • What is Acoustic Radiation? 195
  • The Speed of Sound 199
  • Attenuation of Acoustic Radiation 204
  • Reflection and Refraction of Acoustic Radiation 215
  • Seismic Waves 228
  • References 234
  • Problems 236

CHAPTER 7. NUCLEAR RADIATION: ITS ORIGIN AND PROPAGATION 239

  • The Nuclear Radiation Particle Zoo 239
  • Nuclear Particle Reactions 247
  • Nuclear Particle Reaction Rates 255
  • Attenuation of Nuclear Radiation 257
  • Radiation Exposure and Dose 266
  • Radioactive Decay 268
  • References 277
  • Problems 279

CHAPTER 8. RADIOMETRY, PHOTOMETRY, & RADIOMETRIC ANALYSIS 281

  • Radiometry 281
  • Photometry 287
  • Radiometric Analysis – Range Equations 290
  • Blackbody Radiation 293
  • Reflectance 296
  • References 302
  • Problems 303

CHAPTER 9. SENSOR FUNCTIONS 305

  • Uses of Sensor Systems 305
  • Six Primary Sensor Functions 307
  • Incidental Sensor Functions 309
  • Problems 310

CHAPTER 10. SEARCH 311

  • Introduction to Search 311
  • Circle Packing 313
  • Area Search 319
  • Volume Search 327
  • Incorporating Effects of Non–Unity Detection Probability into Search 330
  • References 332
  • Problems 333

CHAPTER 11. DETECTION 335

  • What is Detection? 335
  • Basics of Detection Theory 336
  • Impact of Signal Fluctuations on Detection 345
  • Impact of Pulse Integration on Detection 350
  • Example: Turbulence Effects on Laser Radar Detection 354
  • System Level Concerns Involving Detection 360
  • Clutter and Clutter Rejection 362
  • References 363
  • Problems 364

CHAPTER 12. ESTIMATION 367

  • Characteristics of Measurements 367
  • Sensor Resolution 369
  • Parameter Estimation 376
  • Discrimination 379
  • Pattern Recognition 383
  • References 386
  • Problems 387

CHAPTER 13. MODULATION AND DEMODULATION 389

  • Modulation and Demodulation 389
  • Amplitude Modulation 394
  • Frequency Modulation 398
  • Phase Modulation 402
  • Pulse Modulation 404
  • Pulse Code Modulation 406
  • References 413
  • Problems 414

CHAPTER 14. IMAGING AND IMAGE–BASED PERCEPTION 415

  • Generalized Images 415
  • Resolution versus Coverage 417
  • Image–Based Perception 422
  • Johnson’s Criteria 426
  • Applications of Johnson’s Criteria 429
  • Information–Based Johnson’s Criteria 435
  • Example: Atmospheric Turbulence Effects on Laser Radar Images 440
  • References 446
  • Problems 448

CHAPTER 15. TRACKING 451

  • Tracking Systems 451
  • Tracking Filters 457
  • Fixed–Coefficient Filters 463
  • Kalman Filters 471
  • Comparison of Fixed–Coefficient and Kalman Filters 474
  • Multisensor, Multiplatform Tracking 475
  • Target Motion Analysis 479
  • References 493
  • Problems 494

APPENDIX A. UNITS, PHYSICAL CONSTANTS, AND USEFUL
CONVERSION FACTORS 497

  • Units 497
  • Non–SI Systems of Units 500
  • Natural Units 505
  • Decibels and Logarithmic Units 506
  • Units of Attenuation 510
  • Dimensional Analysis 512
  • Useful Physical Constants 515
  • Selected Conversion Factors 518
  • Useful Mathematical Relations 521
  • References 533

APPENDIX B. FINITE DIFFERENCE AND FINITE ELEMENT TECHNIQUES 535

  • Finite Difference Approximation of Derivatives 535
  • Finite Difference Solution of Differential Equations 537
  • Finite Element Computation of Definite Integrals 539
  • References 540

APPENDIX C. PROBABILITY AND STATISTICS 541

  • Combinatorial Analysis 541
  • Probability 543
  • Random Variables and Functions of Random Variables 546
  • Statistics 554
  • Variance and Covariance of Vector Random Functions 557
  • References 559