B. Santhanam et P. Maragos, Multicomponent AM-FM demodulation via periodicity-based algebraic separation and energy-based demodulation, IEEE COMMUN, 48(3), 2000, pp. 473-490
Previously investigated multicomponent AM-FM demodulation techniques either
assume that the individual component signals are spectrally isolated from
each other or that the components can be isolated by linear time-invariant
filtering techniques and, consequently, break down in the case where the co
mponents overlap spectrally or when one of the components is stronger than
the other. In this paper, we present a nonlinear algorithm for the separati
on and demodulation of discrete-time multicomponent AM-FM signals. Our appr
oach divides the demodulation problem into two independent tasks: algebraic
separation of the components based on periodicity assumptions and then mon
ocomponent demodulation of each component by instantaneously tracking and s
eparating its source energy into its amplitude and frequency parts. The pro
posed new algorithm avoids the shortcomings of previous approaches and work
s well for extremely small spectral separations of the components and for a
wide range of relative amplitude/power ratios. We present its theoretical
analysis and experimental results and outline its application to demodulati
on of cochannel FM voice signals.