example4_6.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

% ======================================================================
% ctft_develope.m
%========================================================================
clear,close all
t1=20;
p=0.004;
f=1/2;% Hz
t=-t1:p:t1; T=8;
tao=0.5;
x1=u(t+tao)-u(t-tao); x=0;
for i=-t1:t1;
    x=x+u(t-i*T+tao)-u(t-i*T-tao);
end

N=20*T/2;
L=2*N+1; k=-N:N;
w=-10:0.01:10;
X=sinc(w);
for r=1:L;
    an(r)=(1/T)*x1*exp(-j*((-(L-1)/2+r-1)*2*pi/T)*t')*p;
end
an=an*T;
subplot(211)
plot(t,x)
axis([-T,T,-0.2,1.2])
title('The original signal x(t)')
xlabel('Time t')

subplot(212)
%k=-N:N;
%stem(k,an,'r.'),hold on

%text(4,max(an),'The amplitude T*ak of x(t)')
plot(T*w,X,'-')
axis([-N,N,-0.5*max(abs(an)),1.2*max(abs(an))])
xlabel('Frequency index k')