c5_4_1.m

dsp入门与实践一书的源代码

clear all;								
clf;									
N=1224;									
f1=200;									
f2=700;									
f3=1100;								
dt=1/1024;								
sample=1/dt;								
randn('state',sum(100*clock));						
dis=2*rand(1,N);
dis=dis-mean(dis);							
dis=2*dis;									
for k=1:N;									
    w(k)=1*sin(2*pi*f1*k*dt)+1*sin(2*pi*f2*k*dt)+1*sin(2*pi*f3*k*dt)+dis(k);
end

figure(1);								
fw=fft(w);
s=abs(fw).^2;
f=(1:N-1)*sample/N;
plot(f,s(2:N));
xlabel('Frequency /Hz');							
ylabel('Amplitude');								
title('DFT of uniformly sampling signal');				

t=tnonunif(N,1,1);								
for k=1:N;										
    w2(k)=1*sin(2*pi*f1*t(k)*dt)+1*sin(2*pi*f2*t(k)*dt)+1*sin(2*pi*f3*t(k)*dt)+dis(k);
end

for k=1:N;										
    s2(k)=0;
    for n=1:N;									
        s2(k)=s2(k)+w2(n)*(cos(2*pi*t(n)*(k-1)/N)-j*sin(2*pi*t(n)*(k-1)/N));
    end
    s2(k)=abs(s2(k)).^2;
end

figure(2);										
f=(1:N-1)*sample/N;
plot(f,s2(2:N));
xlabel('Frequency /Hz');
ylabel('Amplitude');
title('DFT of additive random sampling signal');

f=(1:N-1)*sample/N;
plot(f,s2(2:N));
xlabel('Frequency /Hz');
ylabel('Amplitude');
title('DFT of additive random sampling signal');