find time shift between two similar waveforms

Question

I have to compare two time-vs-voltage waveforms. Because of the peculiarity of the sources of these waveforms, one of them can be a time shifted version of the other.

Answer 1

If one is time-shifted by the other, you will see a peak in the correlation. Since calculating the correlation is expensive, it is better to use FFT. So, something like this should work:

af = scipy.fft(a)
bf = scipy.fft(b)
c = scipy.ifft(af * scipy.conj(bf))

time_shift = argmax(abs(c))