cross correlation between a noise signal and a determined signal

hi. i try to see the correlation between above two signls is close to zero, but it is not even N is very large, and when i do fft on out_cor, there is tone of determined signal. why is that? thanks for your help.

N=8192*64;
f0=1e3;
fs=64*f0;
n=1:N;
x=0.01*randn(1,N);
y=sin(2*pi*f0*n/fs);
figure(1);
plot(n,x,n,y);
out_cor=xcorr(x-mean(x),y,'unbiased');
figure(2);
plot(out_cor);

Answer 1

[Honglei Chen]

Did you see the scale? When I run your code, the correlation is at the order of 10^-3, I'd say it's fairly small.

HTH

Answer 2

[Jeff Yan]

thanks Honglei, i checked that, it is indeed very small. and the tone is existing all the time. thanks for your help.

regards, jeff