Fetal heart rate detection by a special transform method

A novel method is proposed for the detection of fetal heart rate from abdominal ECG (electrocardiography). The method resembles the computation of a discrete Fourier transform. However, the analyzing functions used have greater correlation with the signal being looked for than the standard sine and cosine functions. The functions are trains of square waves, characterized by the width of the square wave, their periodicity, and some initial phase value. Following the elimination of the maternal ECG contribution to the signal, a triple parametric transform function is computed by multiplying the signal by the analyzing functions and integrating the result. The maximum of the transform obtained this way indicates the average fetal RR interval. Thus the fetal heart rate can be detected. Preliminary application of this method to real and simulated fetal ECG signals is presented. In general, the method can be applied to handle weak, quasi-periodic, sharp signals of various origins