Absolute value of the frequency response for the Kolmogorov-Zurbenko filter (the moving average corresponds to the case k = 1). The vertical dashed black line stands for the cutoff frequency f_c given by Eq. (B.14), while the horizontal coloured lines represent the maximum gains in the stopband α_k = η^k. The vertical dotted coloured lines show the passband frequencies f_p given by Eq. (B.17) for a loss level of 5%, which is represented by the horizontal dotted black line.