1.2 Product Description
The product is a lightweight, portable, detector. It is designed to meet your
detecting and hearing needs by providing advanced detecting functions and
a full range of sound of the fetal heartbeat.
The product is mainly used to detect the fetal heartbeat rate (FHR) and the
sound of the fetal heartbeat (SFH).
The growth and development of a fetus can be found out through
examination of these indices. It is applicable for the department of
gynecology and obstetrics and clinic daily.
1.3 Operating Principle
Fetal Doppler consists of probe (transmitter and receiver) and signal
process unit.
Ultrasonic wave is transmitted from one piezoelectric ceramic at the front of
the probe to the uterus of the pregnant women. Echo is received by the
other piezoelectric ceramic at the front of the probe when ultrasonic wave
reaches the fatal heart. Then it is converted into voltage. This doppler signal
is detected and demodulated from the received signal. And the doppler
frequency is consistent with the rhythm of the fetal systole and diastole.
Once cardiac valves vibrate and a doppler frequency excursion is formed. It
is transmitted an output signal of cardiac valves vibrating, and it is sent to
the loudspeaker for getting a rhythmical sound with the fetal heartbeat.
Simultaneously, it is sent to a counter which calculate periods of heartbeat
that is fetal heartbeat rate (bpm=beat per minute).
The normal range of fetal heart rate:
110 bpm-160 bpm.
