q3.10.m

MatlAB与信号与系统的结合例程

% Program P3_3
% Frequency-Shifting Properties of DTFT
clf;
w = -pi:2*pi/255:pi; wo = 0.4*pi;   % w是从-π到π，中间等间隔
num1 = [1 3 5 7 9 11 13 15 17];    %一维数组分别赋值
L = length(num1);                 %一维数组的长度
h1 = freqz(num1, 1,w);           %h1=1+3e-jw+5e-j2w+7e-j3w+9e-j4w+11e-j5w+13e-j6w+15e-j7w+17e-j8w
n = 0:L-1; %n的取值从0到L-1;
num2 = exp(wo*i*n).*num1;
h2 = freqz(num2, 1, w);         %h2=h1ejw0n               
subplot(2,2,1)                 %原序列的幅度谱
plot(w/pi,abs(h1));grid          
xlabel('w/pi'); ylabel('h1振幅');    %X轴标记为w/π  Y轴标记为h1振幅。
title('Magnitude Spectrum of Original Sequence')
subplot(2,2,2)                    %平移后序列的幅度谱
plot(w/pi,abs(h2));grid
xlabel('w/pi'); ylabel('h2振幅');    %X轴标记为w/π  Y轴标记为h1振幅title('Magnitude Spectrum of Frequency-Shifted Sequence')
subplot(2,2,3) %原序列的相位谱.
plot(w/pi,angle(h1));grid
xlabel('w/pi'); ylabel('h1相位');    %横坐标是w/π，纵坐标是h1相位。
title('Phase Spectrum of Original Sequence')
subplot(2,2,4)                        %平移后的相位谱
plot(w/pi,angle(h2));grid
xlabel('w/pi'); ylabel('h2相位');     %横坐标是w/π，纵坐标是h2相位。
title('Phase Spectrum of Frequency-Shifted Sequence')