New Estimators and Guidelines for Better Use of Fetal Heart Rate Estimators with Doppler Ultrasound Devices
Figure 1
A real Doppler signal (kHz) of 1000 ms, recorded with the second transducer in the fourth-channel: (a) Doppler signal (dashed line) and its envelope (solid line); (b) the envelopes of directional signals corresponding to ultrasound scatters approaching to the transducer (solid line) and moving away from the transducer (dash-dot line), respectively.
(a) Envelope of the real nondirectional Doppler signal
