Examples

In this modern world, we are surrounded by all kinds of signals in various forms. Some of the signals are natural, but most of the signals are manmade. Some signals are necessary (speech), some are pleasant (music), while many are unwanted or unnecessary in a given situation. In an engineering context, signals are carriers of information, both useful and unwanted. Therefore extracting or enhancing the useful information from a mix of conflicting information is the simplest form of signal processing. More generally, signal processing is an operation designed for extracting, enhancing, storing, and transmitting useful information. The distinction between useful and unwanted information is often subjective as well as objective. Hence signal processing tends to be application dependent.
We begin with the concepts of signals and systems in discrete time. A number of important types of signals and their operations are introduced. Linear and shift-invariant systems are discussed mostly because they are easier to analyze and implement. The convolution and the difference equation representations are given special attention because of their importance in digital signal processing and in MATLAB. The emphasis, in this chapter, is on the representations and implementation of signals and systems using MATLAB (Ingle & Proakis, 2010).