bizhi1.m

基于FFT的比值算法

figure(2)
u=zeros(1,100);
s=0;
j=1;
for gg=1:100;
t=0:1/5.12e5:4e-3-1/5.12e5;
f=83.01e3;
N=2048;
n=0:N-1;
x=cos(2*pi*f*t)+1/(10^0.6)*randn(1,N);
w=boxcar(N);
z=x.*w';
y=fft(z,N);
p=abs(y);
q1=max(p);
for d=1:1024;
    if p(1,d)==q1;a=d;
    else d=d;
    end
end
b=a+1;c=a-1;
if p(1,b)==p(1,c);kk=a-1;
elseif p(1,b)>p(1,c);
    q2=p(1,b);
    kk=a+q2/(q2+q1)-1;
    %kk=a+(2*q2-q1)/(q2+q1)-1;
else q2=p(1,c);
    kk=a+(-q2)/(q1+q2)-1;
    %kk=a+(q1-2*q2)/(q1+q2)-1;
end
ff1=-0.0050:0.0010:0.0050;
ff=kk+ff1;
xx=zeros(1,11);
i=1;
for g=1:11;
k=0:2047;
x1=z;
x2=cos(2*pi*k*ff(1,i)/2048);
x11=z.*x2;
xr=sum(x11);
x3=sin(2*pi*k*ff(1,i)/2048);
x12=z.*x3;
xl=sum(x12);
X=sqrt(xr^2+xl^2);
xx(1,i)=X;
i=i+1;
end
xm=max(xx);
for q=1:11;
    if xx(1,q)==xm;kf=q;
    else q=q;
    end
end
ffm=ff(1,kf);
s=s+ffm;
u(1,j)=ffm;
j=j+1;
end
ffm=s/100/4
v=std(u,1)
r=0.15*ffm
stem(n,p)
hold on
plot(n,p,'r')
hold off
axis([0,400,0,800])