Design And Implementation Of Portable Fetal ECG Signal Acquisition System

Fetal ECG monitoring is to monitor the fetal ECG signal, in order to obtain fetalelectrocardiogram (FECG) and then analyse the fetal physiological activity. As one ofthe most effective methods for fetal monitoring, fetal ECG monitoring can timely findabonormal situation of intrauterine fetus, which helps the doctors to take the rightmeasures. Therefore, it’s an important means to ensure the safety of perinatal pregnantwomen and feteus, and it has a considerable guiding significance in the implementationof good prenatal and postnatal care. Fetal ECG monitor mainly includes two aspects:the acquisition of the fetal ECG and fetal ECG extraction, in other words is signalacquisition and signal processing. The two aspects complementary to each other, mustwork together to achieve the best performance.The main work of this paper is the research of the fetal ECG signal acquisitionsystem, and there mainly exist four questions in current systems shown below. First, thefetal ECG acquired from the maternal abdomen with noninvasive methods is very weak,only a dozen to scores? microvolts, therefore it’s easily interfered, and completelysubmerged in interference signals. Second, fetal ECG is seriously interfered by maternalECG whose amplitude is several times of fetal ECG. Third, fetal intrauterine activitiesmay cause a great change in the acquired fetal ECG, thence misdiagnosis phenomenonmay arise easily in fetal ECG monitoring in a short period. Finally, monitoringenvironment will have great influence to pregnant women, which affects the effect offetal ECG signal acquisition.A feasible portable acquisition system targeted at solving the above problems infetal ECG signal acquisition is opportunely proposed in this paper, which mainlyconsists of three functional modules: signal conditioning module, data acquisitionmodule, and SD card storage module. Specifically, Signal conditioning modulecompletely composed of analog circuits, including analog filters and amplifiers, is toprecondition the fetal ECG signal, which is the basic premise to be able to collectcomplete and accurate of fetal ECG. Implemented by the high-precision ADC in themicrocontroller C8051F060, data acquisition module applys over sampling to digitizethe fetal ECG signal, which is the key to capture clear fetal ECG. With themicrocontroller C8051F060, SD card storage module applys the FAT32file system tostore the fetal ECG signal, which is the key to ensure the long time monitoring of fetal ECG. The fetal ECG signal acquisition system adopts the embedded architecture andlow power consumption design to achieve the portable characteristic, in order to meetthe needs of anytime, anywhere for fetal ECG monitoring.In this paper, the portable fetal ECG signal acquisition system is the basic premiseof remote fetal ECG monitoring, which solves the problems of long time andhigh-precision continuous acquisition of fetal ECG whenever and wherever, as well asmake the detection of occasional abnormal fetal ECG more accurate. The separation ofthe two function module, namely signal acquisition module and signal processingmodule, makes the manufacturing costs lower, which enables the acquisition systemmore easily accepted by customers. What is more important is that it has a greatpromoting effect for the development of fetal ECG monitoring.