Method Research And System Implementation Of Accurate Recognition Of Fetal Heart Rate Signal

Ultrasound Doppler fetal heart rate measurement method is the current gold standard for fetal heart rate counting.However,the fetal heart rate extraction algorithm of various fetal heart rate instruments is prone to false detection in the case of high maternal interference in the second stage of labor.Aiming at this deficiency,this dissertation designs and implements the maternal-fetal combined fetal heart rate extraction system,which can judge the degree of maternal interference in the maternal abdominal Doppler fetal heart signal,and switch appropriate fetal heart rate extraction algorithm.For the case of traditional method fault to distinguish fetal and maternal heart rate under high maternal interference,this dissertation proposes a method of combining preferred templates with nonlinear template matching.A time-frequency frame template library containing templates of 24 types of templates is established by clustering a large number of clinically collected cardiac cycle data.The nonlinear processing of the observation frame and the template frame distance by the LReLU function effectively suppresses the influence of the mother interference.The proposed method is compared with the simple template matching.The results show that the detection accuracy of this method is 24% higher than that of the simple template matching method under high maternal interference.Under the case that high maternal interference and low maternal interference coexist,this dissertation proposes a combined maternal-fetal fetal heart rate extracting method,which switch fetal heart rate extracting method according the correlation of fetal Doppler ultrasound signal and pulse signal of maternal finger.The method chooses combining preferred templates with nonlinear template matching method under high interference and auto-correlation method under low interference.The experiment result shows that the average correct ratio of maternal-fetal combined fetal heart rate extraction is 8.8% higher than the preferred template combined with the nonlinear template matching method and 7.5% higher than the auto-correlation method.In this dissertation,the combined maternal-fetal fetal heart rate accurate extraction method is implemented.The upper computer software is realized by C# and Matlab mixed programming,which realized the functions of fetal heart rate extraction,signal quality alarm,fetal heart sound playback,fetal heart rate data storage and so on.