Comparative study on the characteristics of electrocardiac signals in time domain and frequency domain

There are two methods (time domain and frequency domain) for the analysis of electrocardiac signals. In this paper is reported a study on them by way of comparison. With the use of filtering method in frequency domain, certain low frequency components were filtered, the time domain waveform was retrieved by IFFT, and the biphase T wave appeared in time domain. After some high frequency components were filtered, time domain wave was retrieved by IFFT, and amplified, the time domain representation of high frequency ECS could be shown obviously, i.e. there was no evident structure in time domain representation of high frequency components in P- and T-waves, but there was evident structure in high frequency components in QRS complex. The duration of QRS depended upon high frequency components, and it was prolonged by filtering certain high frequency components. The slurring of QRS complex was caused by increasing high frequency components, on ventricular depolarized QRS-complex, there were both triangular pulse-like and a triangular pulse-like waveforms, and their power spectrum had both types of feature, single peak and inversepower spectrum. There was no regularity in the spectrum of entire cycle, P- and T-waves, but these was some structure in QRS wave.