Fig. 2
Rank-frequency plots of NUGC3 dilution and spike-in background datasets. a, b, c, d and e show the rank-frequency plots for the 1.5p pair, 3p pair, 6p pair, single 12p replicate and the 11 UHR replicates against the best estimate of the original signals (marked in black). Meanwhile, the observed alias noise (marked in blue) and the theoretical alias noise S o (f s − f)−α (marked in magenta), are also shown. In each subplot, the sampling frequency f s and the mean square error (MSE is defined as the residual error between the observed and theoretical alias noise) are given as well. Overall, the low MSE values of between 5.67e-4 to 3.58e-3 indicates a good fit between the theoretical alias noise model and the observed alias datapoints. For the NUGC3 dilution set, the 1.5p, 3p, 6p replicates have failed to satisfy the Nyquist sampling criterion of fmax < 2f s at sampling frequencies of 589, 592 and 1045; Undersampling has occurred for these cases. The same can also be concluded for the spike-in background dataset. Only the single 12p case had satisfied the Nyquist criterion at fmax < 3.4f s