cross-correlation of two signal always shows unexpected 0 lag
30 visualizzazioni (ultimi 30 giorni)
Mostra commenti meno recenti
YANAN ZHU
il 20 Nov 2018
Commentato: Honglei Chen
il 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).
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 Commenti
Risposta accettata
Honglei Chen
il 20 Nov 2018
You may want to try
[r,lag] = xcorr(b-mean(b),c-mean(c),'coeff');
HTH
2 Commenti
Honglei Chen
il 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
Più risposte (0)
Vedere anche
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!