Why would anyone want to write another introductory communications textbook? Indeed, I have written seven previous Analog and Digital Communications texts, and the market might appear to be saturated with over one dozen effective textbooks.
The answer to this question can be found in the table of contents of this text. This text takes an integrated approach toward communications, with little dichotomy between Analog and Digital.
Studies of telecommunications in undergraduate Engineering education were traditionally analog. In fact, until the late 1960s, very few schools were teaching digital communication concepts to undergraduates. As digital communications rapidly replaced analog communications during the 1970s and 1980s, some universities attempted to keep up with the times by incorporating some digital communications into a first course in communications. Others proposed separate courses dealing with digital communications, often with analog communications as the prerequisite.
Academicians have debated the importance of analog communications and, indeed, some programs have dropped analog in favor of a more thorough approach toward digital. Others were cautious of this approach since history has proven that recycling often occurs (I wish I had never thrown my skinny neckties away). As one example, communications has cycled between wireless and wired. A long time ago, ti started as wired (e.g., telegraph and early telephone) until we found signals could be propagated. Then the big push was wireless (e.g., radio). Then with the advent of fiber optics and broadband cable, we cycled back to wired (e.g., cable TV and cable modems). And the new millennium is bringing a big push toward wireless...until the next big change occurs. So some predict that "analog may rise again."
Throughout this dialog, textbooks have failed to keep pace. Some authors (I was one of them) wrote separate texts in digital communications hoping the trend would follow a natural progression with many courses dealing exclusively with digital. The standard text resembles a committee project, with about half or more on analog communication, and then separate chapters or sections on digital.
Our evolution continues with the approaches of the 1990s toward Engineering education. With programs resisting a move toward a 5-year BS degree, there was simply not enough room in the undergraduate curriculum to deal separately with analog and digital. The trend is to collapse the two into a single presentation. Indeed, this makes great pedagogical sense since there is really no fundamental difference between them. For example, frequency shift keying (FSK) is simply a special case of frequency modulation (FM).
The text you are currently viewing thoroughly intertwines analog and digital communications. While the two forms of communications are treated simultaneously, the distinctions between them are made very clear, and faculty may still choose to separate the presentation.
In addition to the integrated approach, this text strikes a balance between theory and practice. While the undergraduate engineering student needs a firm foundation in the theory, the student must also be exposed to the real world of Engineering design. This serves two important purposes. The first is that an introduction to the real world serves as a strong motivating factor. Students need some "touchy-feely" to motivate them to spend hours digging through mathematical formulae. The second purpose of real world engineering is to ease the transition from academia to the profession. A graduate's first experience with real-world design should not be a great shock, but instead it should be a pleasant experience and a natural transition from the classroom environment. Consistent with this balanced approach, portions of chapters 3, 4, 5, and 6 deal with contemporary applications. Discussion of these applications is clearly tied to the theory presented in the chapters. The text also contains numerous computer application examples. In particular, many of the graphs are prepared and formulas are solved using MATLABTM. In such cases, the instruction set is presented in the text. Many of the exercises are interactive (i.e., the student is asked to enter various parameters). Block diagram simulations using TinaTM software are also spread throughout the text. An enclosed CD contains copies of all the programs discussed in the text, including M-files for all the MATLAB examples.
The book is intended as an introductory text for the study of analog and/or digital communication systems, with or without noise. Although all necessary background material has been included, prerequisite courses in linear systems analysis and in probability are helpful. Comprehensive appendices explore Fourier analysis, linear systems theory, probability and random processes.
The text stresses a mathematical systems approach to all phases of the subject matter. The mathematics used throughout is as elementary as possible, but is carefully chosen so as not to contradict any more sophisticated approach that may eventually be required. An attempt is made to apply intuitive techniques prior to grinding through the mathematics. The style is informal and the text has been thoroughly tested in the classroom with excellent success.
Chapter 1 forms an introduction to the text with basic definitions of systems and signals and a discussion of techniques to change an analog signal into a digital signal.
With the stage set, the remaining chapters consist of thorough presentations of the broad classes of signal transmission techniques, starting with baseband and working through the various forms of modulation. Within each chapter, analog and digital signals are treated, and design and applications are emphasized. The applications present contemporary uses of the theory described within the chapters, and the presentation emphasizes the thought processes used to reduce the theory to practice.
Appendices review Fourier series and transform, linear systems and filter theory, probability, and noise analysis. Additional appendices present tables of Fourier transforms, tables of error functions and Q functions, a discussion of the software on the enclosed CD, and a list of references for further study.
While this text is intended for use in an integrated approach, separating into analog and digital is possible. If it is used for an introductory course in analog communications, the following sections should be covered:
1.3, 1.4, 2.1, 2.2, 2.4.1, 2.4.2, 2.5.1, 2.5.2, 3.1, 3.2.1, 3.2.2, 3.2.3, 3.2.4, 3.3.1, 3.3.2, 3.3.3, 3.4, 3.5, 3.6.1, 4.1.1, 4.1.2, 4.1.3, 4.2.1, 4.3.1, 4.4.1, 5.1, 5.3.1, 5.4.1, and 5.5.1.
On the other hand, to use this text for a course in Digital Communications, cover the following sections:
1.3, 1.4, 1.5, 1.6, 1.7, 2.3, 2.4.3, 2.5.3, 3.2.5, 3.3.4, 3.4.1, 3.4.3, 3.5.1, 3.5.2, 3.6.2, 3.6.3, 4.1.4, 4.1.5, 4.2.2, 4.3.2, 4.4.2, 4.5, 5.2, 5.3.2, 5.4.2, 5.5.2, 5.6, 6.2, and 6.3.
It gives me a great deal of pleasure to acknowledge the assistance and support of many people without whom this text would not have been possible.
To the many classes of students who are responsive during lectures and helped indicate the clearest approach to each topic.
To the many users of the previous editions who took the time to contact me with comments and suggestions.
To my colleagues at Bell Telephone Labs, Hughes Aircraft Systems, and California State University, Los Angeles. Special thanks go to Professors Fred Daneshgaran, George Killinger, and Lili Tabrizi for their many helpful suggestions.
To three of my students who made major contributions to the MATLAB exercises: Quaboaman (Serge) Ouattara, Francisco Lam, and Anselmo Martinez.
To Dennis J. E. Ross for continual guidance and encouragement.
To the late Professor A. Papoulis who played a key role during the formative years of my education.
I sincerely hope this text is the answer to your prayers. If it is, please let me know. If it isn't please also communicate with me so, together, we can improve engineering education.
Martin S. Roden
California State University, Los Angeles