Fig. 2
From: Multi-tier dynamic sampling weak RF signal estimation theory
Instantaneous frequency \(f_{N=2}\) sampled with \(N_M = 4.1\) showing even zero crossings (\(z=2\) and \(z=4\)): samples just before and just after the second zero crossing, \(n_{z=2,1,l=1}\), \(n_{z=2,2,l=1}\), second zero crossing sample estimate \(\tilde{n}_{N=2,z=2,l=1}\), samples just before and just after the fourth zero crossing, \(n_{z=4,1,l=1}\), \(n_{z=4,2,l=1}\), fourth zero crossing sample estimate \(\tilde{n}_{N=2,z=4,l=1}\). The red “x” indicate the estimated zero crossings obtained by linear interpolation between the sample values just before and just after the zero crossings