  The present study revisits the amplitude modulation phenomenon, specifically
for the robustness in its quantification. To achieve this, a well-resolved
large-eddy simulation (LES) data set at Re_theta= 8200 is used. First, the
fluctuating streamwise velocity signal is decomposed into its small- and
large-scale components using both Fourier filters and empirical mode
decomposition (EMD), allowing the comparison among different separation
filters. The effects of these filters on various definitions for quantifying
the amplitude modulation have been discussed. False positive identification of
the amplitude modulation has also been tested using a randomised signal.
Finally, the impact of the inclination angle of the large-scale structures on
the modulation quantification has been assessed.
