A new method to estimate the instantaneous frequency and bandwidth of cardiovascular time series

Describes a new method to quantify the time-varying spectral content of non-stationary cardiovascular time series by means of the instantaneous amplitude, frequency, and bandwidth. Though the described method is computational complex, it produces better estimates of the IF and, in particular, the LB than other algorithms using time-frequency distributions or direct methods (i.e. differentiating the phase of the analytical time series). In contrast to sequential spectral analysis of short time windows, the method presented may provide instantaneous information on the time-dependent changes in sympathetic and parasympathetic activity within the cardiovascular control system (CCS).