Frequency and biphase estimation of quadratically coupled sinusoids using cumulant projections

Summations of cumulants (projections) along parallel lines in the cumulant domain are formed. The projection procedure first relies on a change of variables through rotation of the cumulant axes. The cumulants are effectively decoupled. Summing the cumulants reduced the dimensionality of the system from six cumulant terms to one term. An eigenstructure-based method for frequency and biphase estimation is offered as an alternative to Fourier schemes on the slice after biphases have been converted to estimable amplitudes by forming symmetric and skew-symmetric projections