Cross coupled signal controlled constrained null filter and separation of superimposed frequency modulated sinusoids

The problem of separation of superimposed frequency modulated (FM) sinusoids is addressed. A cross-coupled signal controlled constrained null filter (CC-SCCNF) is proposed to separate the individual signal from the sum of a number of FM signals whose power spectra may overlap. An advantage of the proposed CC-SCCNF is that one does not have to make any assumption on the mixture of the superimposed FM signals, other than that the number of FM signals is a priori known. A necessary condition is described in terms of the trajectories of the SCCNF coefficients. These trajectories are monitored by measuring the instantaneous Euclidean distance between any two SCCNF trajectories. A proof of the CC-SCCNF convergence to a unique solution for the separation of signals is provided. Several computer simulation results are also presented