Variable frequency evolutionary spectrum

Evolutionary spectral theory provides a means for defining a decomposition of signal energy jointly over time and frequency for processes which exhibit an oscillatory behavior. The oscillatory model of behavior effectively assumes that a process is composed sinusoidal components with slowly-varying time-dependent amplitudes. We expand evolutionary spectral theory by allowing the frequency of the sinusoidal components to vary with time. An estimator of this generalized spectrum is described and examples are presented that illustrate the relative merits of this new approach