chafen1.m

运用自相关法

clc;
clear all;
PI=3.14159;
Fs=1;
w=randn(1,256);
a=1;
b=[1,-0.1,0.09,0.648];
x=filter(b,a,w);
t=1:1:256;%256个时间点 
figure(5),
plot(t,x);
x1=2*sin(2*PI*0.1*t); 
x2=8*sin(2*PI*0.25*t); 
x3=8*sin(2*PI*0.26*t); 
figure(6),
y=x1+x2+x3+x; 
plot(t,y); 
%真实功率谱
Y=fft(y);
figure(7),
plot(abs(Y));
%AR模型参数
[a1 E1]=aryule(y,8);
[a2 E2]=aryule(y,11);
[a3 E3]=aryule(y,14);

%周期图法
window=boxcar(length(y)); %矩形窗
nfft=1024;
[Pxx,f]=periodogram(y,window,nfft,Fs); %直接法
figure(8),
plot(f,10*log10(Pxx));
%AR谱估计功率谱 11阶时
[P,F]=pburg(y,11,nfft,Fs)
pxx=10*log10(P);
figure(9),
plot(f,pxx)