9.1 Introduction

Digital signal processing (DSP) consists of modifying or processing signals in the digital domain. Because of the advances made in the speed and density of IC technology, more and more functions that were once performed in the analog domain have switched over to be processed digitally, such as filtering and frequency selection. Furthermore, digital signal processing has allowed new kinds of operations that weren t possible in the analog domain, such as the Fourier transform. With the high performance and low cost of integrated circuits and microprocessors, digital signal processing has become pervasive. It is built into almost all instruments, as well as such things as cellular telephones, compact disc players, and many automobiles.

This chapter covers what is a signal, ways to characterize signals, ways to characterize signal processing, and the advantages and disadvantages of digital signal processing, compared to analog signal processing. Before many signals can be processed digitally, they must first be converted from analog signals to digital signals in a process called digitizing or analog-to-digital conversion. Some of the common tasks performed in digital signal processing include filtering, sample-rate changing, frequency translation, and converting from the time domain to the frequency domain via the Fast Fourier Transform. Depending on the cost and performance constraints of a particular design, the signal processing task can be implemented in various forms of hardware, ranging from custom integrated circuits to field-programmable gate arrays to off-the-shelf chips, or it can...