Sea Clutter: Scattering, the K Distribution And Radar Performance

✍ Scribed by Keith D. Ward, Robert J. A. Tough, Simon Watts

• Publisher: Institution for Engineering and Technology
• Year: 2006
• Tongue: English
• Leaves: 474
• Series: IET Radar, Sonar, Navigation and Avionics
• Category: Library

✦ Synopsis

Sea Clutter: Scattering, the K-Distribution and Radar Performance gives an authoritative account of our current understanding of radar sea clutter. The authors pay particular attention to the compound K distribution model, which they have developed over the past 20 years. Evidence supporting this model, including a detailed review of the calculation of EM scattering by the sea surface, its statistical formulation, and practical application to the specification, design and evaluation of radar systems are all discussed. The calculation of the performance of practical radar systems is presented in sufficient detail for the reader to be able to tackle related problems with confidence.

This book should be invaluable to specialist radar engineers and academic researchers, and of considerable interest to the wider applied physics and mathematics communities.

Also available:

Target Detection by Marine Radar - ISBN 9780863413599 Low-angle Radar Land Clutter - ISBN 9780852962305

The Institution of Engineering and Technology is one of the world's leading professional societies for the engineering and technology community. The IET publishes more than 100 new titles every year; a rich mix of books, journals and magazines with a back catalogue of more than 350 books in 18 different subject areas including:

-Power & Energy -Renewable Energy -Radar, Sonar & Navigation -Electromagnetics -Electrical Measurement -History of Technology -Technology Management

✦ Table of Contents

Contents......Page 8
1.2 Maritime radar......Page 22
1.3 The modelling of radar returns from the sea......Page 26
1.4 Outline of the book......Page 28
2.1 Overview......Page 34
2.2 The sea surface......Page 36
2.3 Sea clutter reflectivity......Page 38
2.4 Amplitude statistics......Page 40
2.4.1 The compound nature of sea clutter amplitude statistics......Page 43
2.5 Frequency agility and sea clutter......Page 44
2.6 Observations of amplitude distributions......Page 45
2.7 Polarisation characteristics......Page 48
2.8 Clutter spikes and modulations......Page 50
2.9 Coherent properties of radar sea clutter......Page 53
2.10 Spatial characteristics......Page 57
2.10.1 Range ACF......Page 58
2.10.2 Power spectrum analysis of range-time intensity plots......Page 61
3.1 Introduction......Page 66
3.2 The sea surface......Page 68
3.3 EM scattering from the sea at high grazing angles......Page 75
3.4 Imaging ocean currents at high grazing angles......Page 81
3.5 The composite model for scattering at medium grazing angles......Page 91
3.6 Scattering at low grazing angles: beyond the composite model......Page 96
3.7 Scattering from breaking waves......Page 109
3.8 Average backscatter from the ocean at low gazing angles......Page 113
3.9 Imaging ocean currents at low grazing angles......Page 116
4.1 Introduction......Page 122
4.2 Gaussian clutter models......Page 123
4.3 Non-Gaussian clutter......Page 127
4.3.1 Compound models of non-Gaussian clutter......Page 129
4.3.2 The gamma distribution of local power and the K distribution......Page 130
4.3.3 A coherent signal in K-distributed clutter......Page 133
4.3.4 K-distributed clutter with added thermal noise......Page 134
4.3.6 Applications to interferometric and polarimetric processing......Page 135
4.4.1 The Class A and breaking area models......Page 136
4.4.2 Clutter spike models and K phenomenology......Page 141
4.4.3 An analysis of spiky clutter data......Page 144
4.5 The lognormal,Weibull and other non-Gaussian distributions......Page 148
4.6 Coherent clutter modelling......Page 150
4.6.1 The Doppler signatures of different scattering events......Page 151
4.6.2 Some typical experimental results......Page 152
4.6.3 Models of Doppler spectra......Page 155
5.1 Introduction......Page 166
5.2 Generating un-correlated random numbers with a prescribed......Page 167
5.3 Generating correlated Gaussian random processes......Page 168
5.4 Fourier synthesis of random processes......Page 172
5.5 Approximate methods for the generation of correlated gamma distributed random numbers......Page 173
5.6 The correlation properties of non-Gaussian processes generated by MNLT......Page 175
5.7 Correlated exponential andWeibull processes......Page 177
5.8 The generation of correlated gamma processes by MNLT......Page 180
6.1 Introduction......Page 188
6.2 Statistical models for probabilities of detection and false alarm......Page 189
6.3 Likelihood ratios and optimal detection......Page 190
6.4 Some simple performance calculations......Page 192
6.5 The generalised likelihood ratio method......Page 196
6.6.1 A likelihood ratio based approach......Page 198
6.6.2 Generalised likelihood ratio based approach......Page 199
6.7.1 Generalised likelihood ratio based approach......Page 203
6.7.2 Peak within interval detection......Page 207
6.8 Applications to coherent detection......Page 208
6.9.1 Maximum likelihood estimators for gamma and Weibull parameters......Page 211
6.9.2 Tractable, but sub-optimal, estimators for K and Weibull parameters......Page 212
6.10.1 Modified generalised likelihood ratio based detection......Page 214
6.10.2 Modified peak within interval detection......Page 215
6.11 Concluding remarks......Page 216
7.2 The analysis of correlated Gaussian data......Page 218
7.2.2 Xa processing and the whitening filter......Page 219
7.2.3 Xo processing......Page 222
7.3 The Wishart distribution......Page 223
7.3.1 The real Wishart distribution......Page 224
7.3.2 The complex Wishart distribution......Page 225
7.4 Polarimetric and interferometric processing......Page 227
7.4.1 X processing of interferometric and polarimetric data......Page 229
7.4.2 Phase increment processing of interferometric data......Page 231
7.4.3 Coherent summation and discrimination enchantment......Page 233
7.5 Feature detection by matched filtering......Page 235
7.6 False alarm rates for matched filter processing......Page 238
7.6.1 A simple model for the global maximum single point statistics......Page 239
7.6.2 The global maximum of a 1D Gaussian process and the matched filter false alarm curve for a time series......Page 241
7.6.3 Extension to 2D matched filters......Page 244
7.7 A compound model for correlated signals......Page 245
8.1 Introduction......Page 250
8.2 Radar equation and geometry......Page 251
8.3 Normalised sea clutter RCS models......Page 254
8.4 Sea clutter fluctuations and false alarms......Page 258
8.5 Target RCS models and detection probability......Page 264
8.6 Detection performance......Page 275
8.7 Modelling other types of radar......Page 285
9.1 Introduction......Page 288
9.2.1 Control of received signal dynamic range......Page 290
9.2.2 Log FTC receiver for Rayleigh clutter......Page 291
9.2.3 Cell-averaging CFAR detector......Page 292
9.2.4 Linear prediction techniques......Page 314
9.3 Adaptation to changing clutter pdf......Page 315
9.3.1 Fitting to a family of distributions......Page 317
9.3.2 Distribution-free detection......Page 318
9.3.3 Estimation of the K distribution shape parameter......Page 319
9.3.4 Estimation of aWeibull shape parameter......Page 324
9.4.1 Site specific CFAR......Page 325
9.4.3 Exploitation of transient coherence......Page 326
9.4.4 Scan-to-scan integration......Page 327
9.5 Practical CFAR detectors......Page 328
10.1 Introduction......Page 332
10.2.1 Discussion......Page 333
10.2.2 Adaptive radars......Page 335
10.2.3 Specification of adaptive systems......Page 336
10.2.4 Practical performance specification......Page 337
10.3 Performance prediction......Page 342
10.3.2 Clutter speckle component......Page 345
10.3.3 False alarms......Page 346
10.4 Measuring performance......Page 347
10.4.1 Trials......Page 348
10.4.3 Modelling and simulation......Page 349
10.5 Measurement methods and accuracies......Page 350
10.5.1 Probability of detection......Page 351
10.5.3 Statistical analysis of trials......Page 356
A1.1 Introduction......Page 360
A1.2 Finite numbers of discrete events......Page 361
A1.3 An infinite number of discrete events......Page 363
A1.4 Continuous random variables......Page 365
A1.5 Functions of random variables......Page 369
A1.6 The normal process......Page 371
A1.7 The time evolution of random processes......Page 379
A1.8 Power spectra and correlation functions......Page 381
A1.9 The complex Gaussian process......Page 382
A1.10 Spatially correlated processes......Page 384
A1.11 Stochastic differential equations and noise processes......Page 386
A1.12 Miscellaneous results......Page 392
A2.2 The gamma function and related topics......Page 400
A2.3 Some properties of the K distribution pdf......Page 405
A2.4 The Bessel functions In, Jn......Page 411
A2.5 Expansions in Hermite and Laguerre polynomials......Page 414
Appendix 3 Scattering from a corrugated surface......Page 418
A3.1 The integral formulation of the scalar scattering problem......Page 419
A3.2 Helmholtz equation Green's functions in two and three dimensions......Page 421
A3.3 Derivation of the Fresnel formulae......Page 424
A3.4 Approximate de-coupling of the integral equations - the impedance boundary condition......Page 427
A3.5.1 The physical optics or Kirchoff approximation......Page 429
A3.5.2 Small height perturbation theory - PC case......Page 431
A3.5.3 The half-space and reciprocal field formalisms......Page 433
A3.6 Scattering by an imperfectly conducting surface: small height perturbation theory......Page 438
A3.7 Numerical solutions of the scattering problem......Page 442
A3.7.1 Scattering from a perfect conductor......Page 443
A3.7.2 Scattering from an imperfect conductor; modification of the F/B method......Page 451
A3.8 Incorporation of the impedance boundary condition in F/B calculations......Page 455
A3.9 Evaluation of adjunct plane contributions......Page 456
A3.10 Summary......Page 459
Index......Page 464