ABSTRACT
Discrete-time signals are seldom found in nature. Therefore, in almost all cases, the authors will be dealing with the digitization of continuous signals. This process will produce a sequence {x(nT)} from a continuous signal x(t) that is sampled at equal time distance T. Any non-periodic discrete-time signal x(t) with finite energy has a discrete-time Fourier transform, which is found by an approximation of the Fourier transform. The z-transform of a sequence is a transformation of a discrete-time function from its time domain to its frequency domain. It is also a powerful tool to study linear time-invariant discrete systems. A discrete time-invariant system is a physical device or an algorithm that transforms an input signal into another one, called the output signal.
