cross-correlation of two signal always shows unexpected 0 lag
18 vues (au cours des 30 derniers jours)
Afficher commentaires plus anciens
YANAN ZHU
le 20 Nov 2018
Commenté : Honglei Chen
le 20 Nov 2018
Hi,everyone, I got a very strange issue.
b is a signal of 251 samples. c is got by shifting b by 5 sample. (b and c are attached).
![Image 5.png](https://www.mathworks.com/matlabcentral/answers/uploaded_files/195877/Image%205.png)
But when I do xcorr on b and c, the max correlation always occurs at 0 lag. which I do not understand. Can someone help?
Below is my code. Thank you.
load b.mat
load c.mat
figure;
plot(b);hold on;
plot(c);
[r,lag] = xcorr(b,c,'coeff');
[m, i_max]=max(r);
shift=lag(i_max);
% plot(lag,r);
display(shift);
0 commentaires
Réponse acceptée
Honglei Chen
le 20 Nov 2018
You may want to try
[r,lag] = xcorr(b-mean(b),c-mean(c),'coeff');
HTH
2 commentaires
Honglei Chen
le 20 Nov 2018
Since your goal is to look for similarity between two signals, I think in theory the cross correlation really requires both signal to be zero mean. Otherwise, the DC component will affect your result. For example, let's say two signals are uncorrelated and have all positive values. In theory, the correlation coefficient should be 0. However, without removing the means, the result will always be positive.
HTH
Plus de réponses (0)
Voir également
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!