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西交大刘树棠写的《数字信号处理》那本书的所有源代码

clear;close;
t0=10;ts=0.001;
ts1=0.01;
ts2=0.005;
fs=1/ts;fs1=1/ts1;fs2=1/ts2;
df=0.5;
t=[-t0/2:ts:t0/2];

x=sin(200*t);m=x./(200*t);
w=t0/(2*ts)+1;
m(w)=1; 
m=m.*m; m=50.*m;
[M,mn,dfy]=fftseq(m,ts,df);
M=M/fs;
f=[0:dfy:dfy*length(mn)-dfy]-fs/2;
subplot(211);xlabel('time');plot(t,m);grid on;
axis([-0.15,0.15,-1,50]);
subplot(212);
plot(f,abs(fftshift(M)));grid on;
xlabel('frequency');

t1=[-t0/2:ts1:t0/2];
x1=sin(200*t1);
m1=x1./(200*t1);
w1=t0/(2*ts1)+1;
m1(w1)=1;
m1=m1.*m1;m1=50.*m1;
[M1,mn1,df1]=fftseq(m1,ts1,df);
M1=M1/fs1;
N1=[M1,M1,M1,M1,M1,M1,M1,M1,M1,M1,M1,M1,M1];
f1=[-7*df1*length(mn1):df1:6*df1*length(mn1)-df1]-fs1/2;
figure(2);subplot(211);xlabel('time');stem(t1,m1);grid on;
axis([-0.15,0.15,-1,50]);
subplot(212);
plot(f1,abs(fftshift(N1)));grid on;
axis([-500,500,0,1]);
xlabel('frequency');

t2=[-t0/2:ts2:t0/2];
x2=sin(200*t2);
m2=x2./(200*t2);
w2=t0/(2*ts2)+1;
m2(w2)=1;
m2=m2.*m2;m2=50.*m2;
[M2,mn2,df2]=fftseq(m2,ts2,df);
M2=M2/fs2;
N2=[M2,M2,M2,M2,M2,M2,M2,M2,M2,M2,M2,M2,M2];
f2=[-7*df2*length(mn2):df2:6*df2*length(mn2)-df2]-fs2/2;
figure(3);
subplot(211);stem(t2,m2);grid on;
xlabel('time');axis([-0.15,0.15,-1,50]);
subplot(212);
plot(f2,abs(fftshift(N2)));grid on;
axis([-500,500,0,1])
xlabel('frequency');;