TABLE OF CONTENTS The capability of radio waves to provide almost instantaneous distant communications without interconnecting wires was a major factor in the explosive growth of communications during the 20th century. With the dawn of the 21st century, the future for communications systems seems limitless. The invention of the vacuum tube made radio a practical and affordable communications medium. The replacement of vacuum tubes by transistors and integrated circuits allowed the development of a wealth of complex communications systems, which have become an integral part of our society. The development of digital signal processing (DSP) has added a new dimension to communications, enabling sophisticated, secure radio systems at affordable prices.
In this book, we review the principles and design of modern single-channel radio receivers for frequencies below approximately 3 GHz. While it is possible to design a receiver to meet specified requirements without knowing the system in which it is to be used, such ignorance can prove time-consuming and costly when the inevitable need for design compromises arises. We strongly urge that the receiver designer take the time to understand thoroughly the system and the operational environment in which the receiver is to be used. Here we can outline only a few of the wide variety of systems and environments in which radio receivers may be used.
Figure 1.1 is a simplified block diagram of a communications system that allows the transfer of information between a source where information is generated and a destination that requires...
