An improved phonocardiographic method for fetal heart rate monitoring

An improved method for acoustical FHR monitoring is presented reducing the number and length of the faulty sections of the FHR diagram in the case of high disturbances. The method applies an adaptive correlation on the abstracted form of the detected signal power, measured on two frequency channels, furthermore, it utilizes the statistical relations of the time difference between the first and second heart sound, finally, a certainty factor is introduced to enable previous timing data as prediction. The method was justified by comparing of large number of measurements to the simultaneous ultrasound tests. The implementation of the method in a portable electronic circuit enables the long-term FHR monitoring on a fully passive manner