Does xcorr use zero padding to negate end effects?
20 views (last 30 days)
Show older comments
I am new to much of Matlab and signal processing, but would like to know if the Matlab function xcorr automatically zero-pads the two input vectors (in real life these would be two vectors of sampled data) to negate the end effects that usually occur when performing discrete Fourier Transforms, or in this case the discrete FFT.
0 Comments
Answers (1)
Wayne King
on 30 Jan 2013
Edited: Wayne King
on 30 Jan 2013
Hi, xcorr() does pad the DFT of the input vectors to the length
2^nextpow2(2*M-1)
where M is the greater length of the two input vectors. So in the case of autocorrelation, that is clearly the length of the input vector.
In the case of cross correlation with different length vectors, M is the length of the longest vector and the shorter vector is appended with zeros in the time domain before computing the DFT.
2 Comments
Wayne King
on 30 Jan 2013
Hi Richard, No, it will use an padding on the fft() of 2^nextpow2(2*8-1) or 2^4=16
nextpow2(2*8-1) is power of 2 larger than 15 or 4 in this case, since 2^4 is 16.
See Also
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!