MATLAB: Increasing xcorr() resolution

fftxcorrzero padding

Is there a wa y to increase the "resolution" of xcorr?
Something like zero padding for the fft()

Best Answer

  • Zero padding will increase the frequency resolution (i.e., reduce the spacing between frequency components), but does not affect the temporal resolution (the time between samples). The resample function increases the temporal resolution, but does not affect the frequency resolution.
    a = [0, 0, 1, 0, 1, 0, 0];
    b = [0, 0, 1, 1, 1, 0, 0];
    upFactor = 10;
    aUp = resample(a, upFactor, 1);
    bUp = resample(b, upFactor, 1);
    [r, lags] = xcorr(a, b, 'coeff');
    [rUp, lagsUp] = xcorr(aUp, bUp, 'coeff');
    lagsUp = lagsUp/upFactor;
    plot(lags, r, 'b', lagsUp, rUp, 'r');
    It you do not want a normalized cross-correlation, you will need to scale rUp.