Pocket Fetal Doppler is a hand-held obstetrical unit, which can be used in hospital, clinic and home for daily self-check by pregnant woman. It contains components of ultrasonic signal transmitter and receiver, analog signals processing unit, FHR calculating unit, LCD display control unit etc. Sonoline B Pocket Fetal Doppler is a high performance model with (fetal heart rate) LCD digital display. It has 3 work modes:real-time FHR display mode, averaged FHR display mode, and manual mode. It has audio output and can be connected with earphone or recorder with audio input.