# xcorr question - better align two signals

2 visualizzazioni (ultimi 30 giorni)
Fan Mei il 6 Gen 2017
Commentato: Fan Mei il 10 Gen 2017
I tried to align two signal better using the below code. The s1 and s2 is in the attached txt file. However, td I got is -24482. I am wondering if there is a way to improve this function. Please help!!
function [td,ny]=align_signal(s1,s2)
ny=ones(size(s1))*NaN;
[C21,lag21] = xcorr(s2,s1);
C21 = C21/nanmax(C21);
[M21,I21] = nanmax(C21);
t21 = lag21(I21);
if t21<0
ny(-t21:end) = s1(-t21:end);
else
ny(t21:end)=s1(t21:end);
end
td=abs(t21);
##### 0 CommentiMostra -1 commenti meno recentiNascondi -1 commenti meno recenti

Accedi per commentare.

### Risposta accettata

Jordan Ross il 10 Gen 2017
Hello Fan,
Unfortunately, the MATLAB functions that compute the sample cross-correlation from two provided sequences (such as "xcorr" in the Signal Processing Toolbox) cannot deal with incomplete data.
One possible solution is to find the NaN value's in the signals and to ignore the measurements (at that time value) for both sequences. The following code shows how you can remove those NaN's:
% Remove NaNs
s2NanLoc = find(isnan(s2));
s1NanLoc = find(isnan(s1));
nanLocs = unique([s1NanLoc; s2NanLoc]);
s1(nanLocs) = [];
s2(nanLocs) = [];
When I do this with your dataset I am able to get a "td" of 4.
##### 1 CommentoMostra NessunoNascondi Nessuno
Fan Mei il 10 Gen 2017
Thank you so much, Jordan.

Accedi per commentare.

### Categorie

Scopri di più su Correlation and Convolution in Help Center e File Exchange

### Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!