A Digital System for Enhancing the Fetal Electrocardiogram

In order to see the true nature of the fetal electrocardiogram, many varied signal enhancement techniques have been tried. Recently, through the use of coherent time averaging, the successful recovery of the low-voltage portions of the fetal ECG has been demonstrated. The averaging device which has been used has limitations with respect to the recovery of transient changes in the fetal ECG, however. This paper discusses the design of a new type of averaging device that, by giving more weight to the more recent fetal ECGs as they are included in the average, aids in the observation of these transients. A prototype of this averaging system has been built and used to process a limited sample of tape-recorded fetal ECG data. The enhanced fetal ECGs that were obtained are shown.