The use of digital filters in enhancing the fetal electrocardiogram.

The use of a low pass digital filter (implemented as a software routine upon a minicomputer) to enhance repetitive biological signals immersed in low frequency noise is described. The method by which a digital filter can emulate a hardware moving window averaging process is outlined. The results of applying such a filter to the enhancement of the fetal electrocardiogram are presented. The criteria used in setting up the filter are also discussed.