On characterization and application of oscillatory almost-cyclostationary processes

The class of the second-order oscillatory almostcyclostationary processes is characterized. These processes have autocorrelation function which is the superposition of amplitudeand angle-modulated complex sinewaves, where the modulating functions, referred to as evolutionary cyclic autocorrelation functions, depend on both time and lag parameter. This class of processes includes that of the almost-cyclostationary processes. The problem of statistical function measurements is addressed for the special case of amplitude-modulated time-warped almostcyclostationary processes. These processes are shown to be a suitable model for the electrocardiogram.