Fetal heart beat detection by Hilbert transform and non-linear state-space projections

This study describes an integrated approach for fetal heart beat detection from abdominal ECG signals. The signal is first processed by the first-order difference operation, and then, the envelope of the differentiated signal is given by the Hilbert transform, which indicates both the maternal and fetal heart beats. After that, the non-linear state-space projections is applied to the envelope signal to remove the maternal heart beats, obtaining the fetal heart beats envelope. The validity and performance of the described method are confirmed through experiments on real ECG data. A comparison with the well-known independent component analysis method has also been presented.