limxiuzhengxiefangcha.m

功率谱估计程序

%修正协方差法，选用电力系统谐波信号作为输入信号。参考书目：现代数字信号处理，皇甫堪等，电子工业出版社。212页。
clc;clear all;close all;
f1=50;ts=1/1000;n=1:256;N=256;fs=1000;p=10;delta=0.101043;
x(1:128)=2*sin(2*pi*f1*(1:128)*ts);
x(129:256)=2*sin(2*pi*f1*(129:256)*ts)+0.1*sin(2*pi*350*(129:256)*ts)+0.2*sin(2*pi*400*(129:256)*ts);
for l=1:p
    for k=1:p
        s1=0;
        for n=p:N-1
            s1=s1+x(n-k+1)*x(n-l+1)/(2*(N-p));
        end
        s2=0;
        for n=0:N-1-p
            s2=s2+x(n+l+1)*x(n+k+1)/(2*(N-p));
        end
        r(l,k)=s1+s2;
    end
end

for l=1:p
  
        s1=0;
        for n=p:N-1
            s1=s1+x(n+1)*x(n-l+1)/(2*(N-p));
        end
        s2=0;
        for n=0:N-1-p
            s2=s2+x(n+l+1)*x(n+1)/(2*(N-p));
        end
        r1(l,1)=s1+s2;

end
a=-inv(r)*r1;

for f=0:fs/2
    s=0;
    for k=1:p
        s=s+a(k)*exp(-i*2*pi*f*k/fs);
    end
    P(f+1)=delta/(abs(1+s))^2;
end
f=0:fs/2;
semilogy(f,P)