Spectral investigations of intraluminal impedance signals

In this paper, an investigation of the spectral characteristics of intraluminal impedance signals using local Hilbert-Huang transform is presented. The impedance waveform may contain three main events: reflux event, swallow event and baseline region corresponding to no activity. The three events are analysed using local Hilbert-Huang transform to characterize the frequency contents of each event. In addition to the results of the Hilbert-Huang transform a time domain description of each event is presented.