Using discrete Hilbert transformation for interval-related calculation of the respiration rate in neonates.

From the basis of the fast Fourier transformation (FFT), the discrete Hilbert transformation (DHT) is used to compute the instantaneous respiration rate in neonates. This interval-related computation of respiration rate must be combined with a concept of adaptive filtration of the respiratory movements. This strategy is performed by adaptive recursive estimations of mean values with different adaptation constants. Additionally, a frequency band limitation is carried out on the basis of the peak characteristic of the power spectrum (respiratory movements). By means of the adaptive estimation of the variance of respiratory movements, an amplitude-time window is calculated to choose between epochs with breaths and apnoea.