close?all;clc;clear?all;
fs=10000;
f0=200;
f1=50;
f2=600;
T=0.2;
t=0:1/fs:T;
x1=sin（2*pi*f0*t）;
subplot（211）;
y1=（1/T）*xcorr（x1x1）/fs;
t1=（0:1:length（y1）-