1.1 OBJECTIVES OF THIS INTRODUCTORY CHAPTER

To motivate you to read and study the many advanced and fascinating digital communications (DIGCOM) and signal-processing subjects covered in this book, I believe that an introductory and overview chapter is well justified.

In Fig. 1.1, the outline of the material covered in this volume is presented in a block diagram form. Digital signal processing (DSP) plus transmission techniques and network and technology principles, techniques, and applications are presented in depth in Chapters 2 through 12. In this introductory chapter, we present an overview of the later advanced chapters and highlight the close relationship among the chosen topics. Numerous block diagrams (flowcharts) highlight the synergisms between the topics presented in various chapters.

Figure 1.1: Outline of material covered in this book.

We attempt to point out to you the benefits that could accrue from an indepth study of this book. A sampling of such benefits is indicated by the questions below, which are answered in this introductory chapter:

1. Why do we need ISDN?

2. Why digital speech?

3. What is wrong with PCM?

4. What are the echo-cancellation requirements?

5. How can circuit capacity be multiplied with DSI?

6. Why should we study or develop new digital TV-processing techniques?

Brief tutorials are included in several sections of this chapter to complement the material presented in the respective chapters. To expedite comprehension...