Communication Systems Principles Using MATLAB

1Signals and Systems

1.1 Chapter Objectives

On completion of this chapter, the reader should:

1. Be able to apply mathematical principles to waveforms.
2. Be conversant with some important terms and definitions used in telecommunications, such as root‐mean‐square for voltage measurements and decibels for power.
3. Understand the relationship between the time‐ and frequency‐domain descriptions of a signal and have a basic understanding of the operation of frequency‐selective filters.
4. Be able to name several common building blocks for creating more complex systems.
5. Understand the reasons why impedances need to be matched, to maximize power transfer.
6. Understand the significance of noise in telecommunication system design and be able to calculate the effect of noise on a system.

1.2 Introduction

A signal is essentially just a time‐varying quantity. It is often an electrical voltage, but it could be some other quantity, which can be changed or modulated easily, such as radio‐frequency power or optical (light) power. It is used to carry information from one end of a communications channel (the sender or transmitter) to the receiving end. Various operations can be performed on a signal, and in designing a telecommunications transmitter or receiver, many basic operations are employed in order to achieve the desired, more complex operation. For example, modulating a voice signal so that it may be transmitted through free space or encoding data bits on a wire all entail some sort ofprocessing ...