Dr. V. V. Ol'shevskii is perhaps most familiar to Western readers as the author of "Characteristics of Sea Reverberation," published in translation by Consultants Bureau (New York, 1967). The present book, "Statistical Methods in Sonar," is, in part, a sequel to the first book, where now the author's stated purpose is "to acquaint a broad range of specialists with the use of contemporary statistical methods for solving theoretical and applied sonar problems. " As the author quite properly observes, the work is illustrative, devoted to a variety of relevant, specific technical problems from an analytical point of view, and is not in any way intended to be an all-inclusive treatise. Nevertheless, as the reader can verify subse­ quently, the author has succeeded in accomplishing his stated purpose. He has, moreover. provided us with a use­ ful and, in a number of instances, provocative work, which even five years after its original appearance retains its freshness and interest with material not to date covered in other books on the subject (for example, see Horton [~Q], Stephens [41] ). * In this Foreword we first concisely review the author's material, on a chapter-by-chapter basis, after which a short general critique is given. Attention is called to various topics of particular interest to the professional audience. as well as to a number of highlights which deserve the reader's notice (a few additional comments on the technical editing are then included).

Table of Contents:
I. Introductory Remarks.- §1. Some Definitions.- §2. The Sonar Model.- §3. Sonar and Radar.- §4. Statistical Problems of Sonar.- II. Procedural Fundamentals of Experimental Research in Sonar.- §5. Principal Tasks of Experimental Research.- §6. The Structural Diagram of Quantitative Experimental Research.- §7. Discrimination Functional of the Probability Characteristic and Its Statistical Estimate.- §8. The Base Model.- §9. Interpretation of Experimental Results.- §10. Objects of Experimental Research in Sonar.- III. Probability Models of Hydroacoustic Signals.- §11. Varieties of Models.- §12. A Priori Information and Probability Models.- §13. Methods for Describing Hydroacoustic Signals in Terms of Probability.- §14. Classification of Hydroacoustic Signals.- §15. Canonical Models.- §16. Parametrical Models.- §17. Additive-Multiplicative Constructive Models.- §18. Models in the Form of Oscillations with Random Amplitude and Phase.- §19. Complex Representation of Signals.- IV. The Emitted Signals.- §20. Signal Classification.- §21. Complex Representation of Emitted Signals.- §22. Ambiguity Function and Diagrams.- §23. Signals with Sinusoidal Occupation.- §24. Frequency-Modulating Signals.- §25. Noiselike Signals.- V. Echo Signals.- §26. Classification of Objects of Research and the Conditions under Which They Are Observed.- §27. Representation of Echo Signals and Their Probability Characteristics.- §28. The Model of an Echo Signal of Known Form with Constant Lag and Change in Time Scale.- §29. Echo Signal with Fluctuating Amplitude.- §30. Echo Signal Consisting of an Additive Mixture of a Signal of Known Form and a Random Component.- §31. Echo Signal with Random Amplitude Modulation.- §32. Echo Signal with Random Phase Modulation.- §33.Echo Signal with Random Frequency Modulation.- §34. Model of an Echo Signal in the Form of a Sum of Elementary Signals.- VI. Marine Reverberation.- §35. Classification of Reverberatory Signals.- §36. Discrete Canonical Model of Reverberation.- §37. Complex Representations.- §38. Characteristics of the Random Parameters of Elementary Scattered Signals.- §39. Average Value of Reverberation.- §40. Autocorrelation Function for the Complex Envelope of Reverberation.- §41. Energy Spectrum of the Complex Envelope of Reverberation.- §42. Evaluation of the Frequency-Time Cross-Correlation Function for the Complex Envelopes of the Emitted Signal and Reverberation.- §43. Generalization for the Case of Elementary Scattered Signals of Different Forms.- §44. Space-Time Correlation of Reverberation when Wideband Signals Are Emitted.- §45. One-Dimensional Semi-invariants.- §46. Probability Distributions for Instantaneous Values of Reverberation and Its Envelope.- VII. Problems of Detecting Echo Signals in the Presence of Interference.- §47. Specific Features of Detecting Echo Signals in Sonar.- §48. Probability Characteristics of Detection.- §49. Typical Probability Distributions of the Output Effect.- §50. Incoherent Detection of Simple Echo Signals with a Linear Detector.- §51. Incoherent Detection of a Noiselike Echo Signal with Quadratic Detection and Smoothing (“Energy Detection”).- §52. Coherent Detection of a Noiselike Echo Signal Using Cross-Correlation Processing.- §53. The Effect of Reverberation Interference on Echo Signal Detection.- §54. Detection with Multichannel Systems, and Discussion of Results.- VIII. Elements of the Theory of Statistical Measurement.- §55. Basic Stages of Statistical Measurements.- §56. Statistical Measurement Errors.-§57. Formation of a Statistical Estimate.- §58. Statistical Measurement Errors of the Characteristics of Nonstationary Homogeneous Random Processes.- §59. Optimization of the Parameters of the Statistical Measuring System.- §60. Adaptive Optimization.- IX. Inverse Probability Problems in Sonar.- §61. Direct and Inverse Problems.- §62. Correctness Conditions.- §63. Determination of the Probability Density for the Rates of Movement of Scatterers.- §64. Determination of the Spectrum of the Fluctuations in the Rate of Movement of Scatterers.- §65. Determination of the Relative Level of Coherent Scattering.- §66. Determination of the Average Number of Scatterers.- §67. Determination of the Frequency Properties of Scatterers.- §68. Determination of the Spatial Distribution of Scatterers.- Conclusion.