Study On Fetal ECG Monitoring System

With the development of society，the concept of “people foremost”hasinfiltrated into every person’s life gradually，particularly paying attention to theneonatal health status which concerns the future population quality. Fetal monitoringhas been widely used as one of the important means of protecting the safety ofperinatal pregnant women and fetuses. One of the most effective method in fetalmonitoring-fetal ECG monitoring which monitors the signal and then understandsthe fetal heart activity status. The fetal ECG monitoring consists of two mainparts----Fetal ECG extraction, research and manufacturers of Fetal ECG monitoringsystem. These two parts are both the focus of current research. The content of thisthesis mainly concentrates on the above two parts.Fetal ECG extraction: As Fetal ECG is a kind of typical biomedicalphysiological signal, the extraction has a certain degree of difficulty.Moreover, thefetal ECG is extracted from maternal abdomen, and the maternal ECG and othersignal will be mixed into the extracted signal, so it is more difficult to extract theFetal ECG signal. This thesis provides two ways of denoising to solve problems---Wavelet thresholding denoising algorithem and adaptive filtering.1、The wavelet transformotion is used as a common signal extraction method.The wavelet thresholding denoising algorithem is used to achieve the extraction ofthe fetal ECG in this thesis. The method can make the analysis of signal in both thetime domain and frequency domain,(When the resolution in the frequency domain ishigh, the resolution in the time domain is low.And when the resolution in thefrequency domain is low, the resolution in the time domain is high. The methodhave the function of the automatic zoom) to effectively distinguish the mutationpart and the noise of the signal and achieve to denoise the signal. However, it is noteasy to estimate the noise variance in the wavelet thresholding denoising algorithemand there are disadvantages of the feature of real time response, so this requires us tomake further improvement of the method. Likewise Self-adaptive Filtering Method is also used as a common signalextraction method. We use the adaptive filtering to achieve the extraction of FetalECG in the thesis. This method is respectively collected the two types of signal fromthe maternal chest and abdomen,the signal of the abdomen as the system’s originalinput and signal of the chest as the system’s reference input. With the adaptiveprocessing, with continuously adjusting the coefficient of adaptive filter in theprocess, we can get the best system output, thereby achieving the extraction of thefetal ECG. Adaptive filtering is an easier and better in the area of Real-time and theamount of calculation. So it meets the fetal ECG extraction field with stringentrequirements2、The establishment of fetal monitoring system: Fetal monitoring system on thebasis of PC is established in this thesis of two functions: data acquisition and dataprocessing. The system includes the case library to achieve data managementsimultaneouslyFetal monitoring system on the basis of PC mainly includes of two parts:software and hardware. The hardware is made up of the electrocardiogram amplifierand the AD data acquisition card to achieve the function of signal amplification andA/D converting.The software use the Windows XP system, C#, and SQL Serverprogramming to Control AD card functions of data acquisition, data processing anduser and data management.