example4_9.m

经典《信号与系统》教程的matlab例程,对深入理解信号与系统相关概念有很大帮助

% ======================================================================
% Example4_9
%========================================================================
clear,close all
t1=5;
p=0.01;
t=-t1:p:t1; 
x1=u(t-1)-u(t-4);
x2=0.5*(u(t-2)-u(t-3));
x=x1+x2;
w1=4*pi;
N=512;
k=-N:N;
w=k*w1/N;
X1=x1*exp(-j*t'*w)*p;
phi1=angle(X1);
X1=abs(X1);

X2=x2*exp(-j*t'*w)*p;
phi2=angle(X2);
X2=abs(X2);

X=x*exp(-j*t'*w)*p;
phi=angle(X);
X=abs(X);

subplot(331)
plot(t,x1)
axis([-1,5,0,2])
title(' Signal x1(t)')

subplot(334)
k=-N:N;
plot(w/(2*pi),X1,'r')
ylabel('The magnitude')
axis([-2,2,0,4])

subplot(337)
plot(w/(2*pi),phi1,'r')
ylabel('The phase')
xlabel('Frequency in Hz')

subplot(332)
plot(t,x2)
axis([-1,5,0,2])
title(' Signal x2(t)')

subplot(335)
k=-N:N;
plot(w/(2*pi),X2,'r')

axis([-2,2,0,4])

subplot(338)
plot(w/(2*pi),phi2,'r')
xlabel('Frequency in Hz')

subplot(333)
plot(t,x)
axis([-1,5,0,2])
title(' Signal x(t)')

subplot(336)
k=-N:N;
plot(w/(2*pi),X,'r')

axis([-2,2,0,4])

subplot(339)
plot(w/(2*pi),phi,'r')
xlabel('Frequency in Hz')