DISCRETE-TIME SIGNALS

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.
Signals are broadly classified into analog and discrete signals. An analog signal will be denoted by xa(t), in which the variable t can represent any physical quantity, but we will assume that it represents time in seconds. A discrete signal will be denoted by x(n), in which the variable n is integer-valued and represents discrete instances in time.
In MATLAB we can represent a finite-duration sequence by a row vector of appropriate values. However, such a vector does not have any
information about sample position n (Ingle & Proakis, 2010).