Formula 1 G~xx(f)=ζT[∣X(f,T)∣2]\tilde{G}_{x x}(f)=\frac{\zeta}{T}\left[\left|X(f, T)\right|^{2}\right]G~xx(f)=Tζ[∣X(f,T)∣2] Formula 2 G~yy(f)=ζT[∣Y(f,T)∣2]\tilde{G}_{y y}(f)=\frac{\zeta}{T}\left[|Y(f, T)|^{2}\right]G~yy(f)=Tζ[∣Y(f,T)∣2]