xcorr zero lag

2012 1 1
1 个回答
18 次查看（30 天）

0 个投票

Dear all, How can I use xcorr for 0 lags? In the test I'm running I don't want to 'slide' one sequence over another but keep them fixed. Thanks in advance. Happy new year! Diego

3 个评论
显示 1更早的评论 隐藏 1更早的评论

Diego
Diego 2012-1-1
This doesn't work
X1=xcorr(P,Q,0, 'coeff');
I need the signals to be superimposed but avoiding the sliding. Does this makes sense at all?
Diego
Diego 2012-1-1
I'm correlating sequences of length 8.
Is this right?
Thanks,
Diego
the cyclist
the cyclist 2012-1-1
I don't have the Signal Processing Toolbox, so I can't check myself, but the syntax in your first comment looks right to me. Can you give a more complete example of the code you have written, the result, and why specifically you believe it to be wrong (or not what you expect)?

请先登录，再进行评论。

请先登录，再回答此问题。

回答（1 个）

Wayne King
Wayne King 2012-1-1

0 个投票

Hi Diego, Why doesn't this work?
[c,lags] = xcorr(randn(1000,1),rand(1000,1),0,'coeff');
This gives you exactly what you have described; the cross correlation between two input vectors at zero lag.
c is the value of the normalized cross correlation sequence at zero lag.

4 个评论
显示 2更早的评论 隐藏 2更早的评论

Diego
Diego 2012-1-1
Hi Wayne,
Thanks for your reply.
When I use 0 lags the plotted figures get side by side, not superimposed as when I don't declare the lags.
This is the code of the plot:
delay=d-max(length(P),length(Q));
figure,plot(P);
hold,plot([delay+1:length(P)+delay],Q,'r');
Happy new year!
Diego
Wayne King
Wayne King 2012-1-1
you're not telling me what d means in the above. are P and Q different lengths? If they are, you can't use the 'coeff' option.
Diego
Diego 2012-1-1
ughh I'm so sorry for omitting the information... the code just grows a lot and is a little messy at this time.
P and Q are the same length.
Thanks for your patience!
P=[M(l,i:i+rep-1)];
Q=[M(z,j:j+rep-1)];
[m,d]=max(X1);
Diego
Diego 2012-1-3
It seems the problem was using the 'delay' for plotting.
I just removed it since at 0 lags it seems to be useless and the plot works as expected.
Many thanks,
Diego

请先登录，再进行评论。

类别

在 帮助中心 和 File Exchange 中查找有关 Correlation and Convolution 的更多信息

标签

提问:

Diego
Diego
2012-1-1

Community Treasure Hunt

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

Start Hunting!

Translated by