TABLE OF CONTENTS Although most naturally occurring signals are of the analog variety (continuous-amplitude and continuous-time variation), we are finding that conversion of these signals to a digital form (discrete-time and discrete-amplitude variations) provides many advantages. For example, digital signals can be stored on computer floppy or hard disks. They can be compressed to save space, converted to other formats, or transmitted in combination with other signals. Digital forms of signals are truly becoming the standard in everyday use as compact discs (CDs) for audio and multimedia applications can attest. Therefore, the remainder of this text is devoted to the application of filtering techniques to digital signals.
The material in this chapter should provide a review of the basic principles of discrete-time systems that are necessary to understand the material presented in the remainder of the text. In the first section of this chapter we will discuss the process of converting analog signals into a digital form. Next, we will develop methods of dealing with discrete-time signals in both the time domain and frequency domain. We will also learn how to find the frequency response of a discrete-time system as well as how to play digitized waveforms on a computer equipped with a sound card.
As indicated in the introduction, most of the signals that we deal with every day are known as analog signals. This type of signal has a continuous variation in both time and amplitude, as shown in Figure 5.1(a). In order to convert this analog...
