UploadFile_6417

80 Chapter 3 THE DISCRETE-TIME FOURIER ANALYSIS
1
Magnitude Response
|H|
0.8
0.6
0.4
0.2
0
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
frequency in π units
1
Phase Response
Phase in π Radians
0.5
0
−0.5
−1
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
frequency in π units
FIGURE 3.9 Plots for Example 3.16
>> subplot(2,1,1); plot(w/pi,magH); grid; axis([0,1,0,1])
>> xlabel(’frequency in pi units’); ylabel(’|H|’);
>> title(’Magnitude Response’);
>> subplot(2,1,2); plot(w/pi,angH/pi); grid
>> xlabel(’frequency in pi units’); ylabel(’Phase in pi Radians’);
>> title(’Phase Response’);
From the plots in Figure 3.9 we see that the filter is indeed a lowpass filter. □
3.4 SAMPLING AND RECONSTRUCTION OF ANALOG SIGNALS
In many applications—for example, in digital communications—realworld
analog signals are converted into discrete signals using sampling
and quantization operations (collectively called analog-to-digital conversion,
or ADC). These discrete signals are processed by digital signal
processors, and the processed signals are converted into analog signals
using a reconstruction operation (called digital-to-analog conversion or
Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.