Application of the Lomb-Scargle Periodogram to InvestigateHeart Rate Variability during Haemodialysis

Figure 2

Signal masked by noise (solid line in upper graph) with 20% of RR intervals discarded at random (the remaining RR intervals appear as circles in upper graph). The frequencies of the original sinusoid are both accurately located at ω_l = 0.095 Hz and ω_h = 0.275 Hz and are the only peaks to exceed a FAP of 50% in the resulting periodogram. (a) Synthetic signal. (b) Lomb–Scargle spectrum.