Zon Hendri, Muhammad Ridha Makruf


Microcontroller Based Fundascope AT89s51 (Portable) is a device used to detect the
fetal heartbeat in women pregnant. This tool adopts the principle of using the technique of
fetal doppler auscultation (listen check).
This tool depends on the sound of the fetal heartbeat is received, because it is just
recording it. The sound of the fetal heart rate has a very low frequency, ranging from 12-20
Hz, while the frequency of the sound of mother's heartbeat is between 40-50 Hz. So the
frequency difference is quite small, so it is quite difficult to separate the two.
Based on the existing conditions of the design of these tools must be adapted to these
conditions. Because the sensors used in this tool is Stetoskope and Mic Condensor, we need a
proper frequency divider circuit. So the sound of the fetal heartbeat can be heard clearly. The
series of filters that are used in this module is a Band Pass Filter.
According to data from measurements taken at Hall Health Facility Security to the
level of error that occurred, then obtained an errors reaches -1.32% at 30 BPM calculation,
21:06% at 60 BPM calculation, -3.57% at 120 BPM calculation, - 1.28% at 180 BPM
calculation and -1.37% at 240 BPM calculation.
After the process of making and planning literature studies, experiments, testing and
data collection tools, the authors conclude that the condensor mic it can also function as a
sensor to record the fetal heartbeat, although the results are not as good of a detector that
uses ultrasound, as well as utilizing microcontroller as a means of calculate.

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