Digital Signal Processing Systems, Basic Filtering Types, and Digital Filter Realizations - Digital Signal Processing: Fundamentals and Applications - page 161

CHAPTER

6

Digital Signal Processing Systems,
Basic Filtering Types, and Digital
Filter Realizations

CHAPTER OUTLINE

6.1 The Difference Equation and Digital Filtering ................................................................................. 161
6.2 Difference Equation and Transfer Function ..................................................................................... 166
6.2.1 Impulse Response, Step Response, and System Response ............................................169
6.3 The z-Plane Pole-Zero Plot and Stability........................................................................................ 172
6.4 Digital Filter Frequency Response ................................................................................................. 178
6.5 Basic Types of Filtering ................................................................................................................ 186
6.6 Realization of Digital Filters.......................................................................................................... 192
6.6.1 Direct-Form I Realization ...........................................................................................193
6.6.2 Direct-Form II Realization ..........................................................................................193
6.6.3 Cascade (Series) Realization ......................................................................................195
6.6.4 Parallel Realization....................................................................................................196
6.7 Application: Signal Enhancement and Filtering............................................................................... 199
6.7.1 Pre-Emphasis of Speech ............................................................................................200
6.7.2 Bandpass Filtering of Speech .....................................................................................203
6.7.3 Enhancement of ECG Signal Using Notch Filtering.......................................................205
6.8 Summary ..................................................................................................................................... 206

OBJECTIVES:
This chapter illustrates digital filtering operations for a given input sequence; derives transfer functions
from the difference equations; analyzes the stability of the linear systems using the z-plane pole-zero plot;
and calculates the frequency responses of digital filters. Then the chapter further investigates realizations
of the digital filters, and examines spectral effects by filtering speech data using the digital filters.

6.1 THE DIFFERENCE EQUATION AND DIGITAL FILTERING
In this chapter, we begin with developing the filtering concept of digital signal processing (DSP)
systems. With the knowledge acquired in Chapter 5, dealing with the z-transform, we will learn how to
describe and analyze linear time-invariant systems. We also will become familiar with digital filtering
types and their realization structures.