 SO rapidly (e.g., witness the recent improvements in frequency synthesizers boosting frequency hop rates from the Khops/sec to the Mhops/sec ranges over SS bandwidths in excess of a GHz) that today's primarily theoretical concepts will be realized tomorrow. Unclassified research and developments in spread-spectrum communica- tions have arrived at a point of maturity necessary to justify a textbook on SS communications that goes far beyond the level of those available on today's market. Such is the purpose of Spread Spectrum Communications. Contained within the fourteen chapters of its three volumes is an in-depth treatment of SS communications that should appeal to the specialist already familiar with the subject as well as the neophyte with little or no background in the area. The book is organized into five parts, within which the various chapters are for the most part self-contained. The exception is Chapter 3, Part 1, which deals with basic concepts and system models and serves as a basis for many of the other chapters that follow. As would be expected, the more traditional portions of the subject are treated in the first two parts, while the latter three parts deal with more specialized aspects. The authors envision that an introductory one-semester course in SS communications taught at a graduate level in a university might cover all or parts of Chapters 1, 3, 4, of Part 1, Chapters 1 and 2 of Part 2, and Chapters 1 and 2 of Part 4. In composing the technical material presented in Spread Spectrum Communications, the authors have intentionally avoided referring by name to specific modern SS systems that employ techniques such as those dis- cussed in many of the chapters. Such a choice was motivated by the desire to offer a unified approach to the subject that stresses fundamental princi- ples rather than specific applications. Nevertheless, the reader should feel confident that the broad experience of the four authors ensures that the material is practical as well as academically inspiring. In writing a boo