Modern Digital and Analog Communication Systems PDF

INTRODUCTION

Over the past decade, the rapid expansion of digital communication technologies has been simply astounding. Internet, a word and concept once familiar only to technologists and the scientific community, has permeated every aspect of people's daily lives. It is quite difficult to find any individual in a modern society that has not been touched by new communication technologies ranging from cellular phones to Bluetooth. This book examines the basic principles of communication by electric signals. Before modern times, messages were carried by runners, carrier pigeons, lights, and fires. These schemes were adequate for the distances and "data rates" of the age. In most parts of the world, these modes of communication have been superseded by electrical communication systems,⁺ which can transmit signals over much longer distances (even to distant planets and galaxies) and at the speed of light.

Electrical communication is dependable and economical; communication technologies improve productivity and energy conservation. Increasingly, business meetings are conducted through teleconferences, saving the time and energy formerly expended on travel. Ubiquitous communication allows real-time management and coordination of project participants from around the globe. E-mail is rapidly replacing the more costly and slower "snail mails." E-commerce has also drastically reduced some costs and delays associated with marketing, while customers are also much better informed about new products and product information. Traditional media outlets such as television, radio, and newspapers have been rapidly evolving in the past few years to cope with, and better utilize, the new communication and networking technologies. The goal of this textbook is to provide the fundamental technical knowledge needed by next-generation communication engineers and technologists for designing even better communication systems of the future.