Research On ECG Signal Acquisition System Based On Virtual Instrument

Virtual instrument technology is a new kind of measurement technology,which has been developing with modern measurement technology,computer science and technology.On the basis of TLC1549 A/D converting chip and AT89C51 MCU,this paper has designed ECG signal acquisition circuit with communication realized by using Lab VIEW to connect serial port with AT89C51 and processing the ECG data acquired,and then.the ECG signal display and basic analysis are realized.Several key problems during the process of pretreating the ECG signal,such as eliminating the broadband noise that produced in ECG signal,filtering baseline drift,R wave detection etc are discussed thoroughly by the lap joint of the hardware circuit,related calculation of analogous circuit.software programming and experimental research.Then the accuracy of the system test are verified by ECG database and human samples test results together.The design of this system includes two parts of hardware design and software design.The hardware circuit of this system mainly includes the design of signal conditioning circuit and 89C51 core circuit.The software program of this system mainly includes the design of A/D converting chip and MCU controlling program,the reading module of Lab VIEW file,the module of filtering baseline drift,the positioning module of R wave and the position module of QRS wave,etc.By the verification test of MIT ECG database sample,which is internationally recognized,it shows that the algorithm of this system can effectively inhibit the noise signal in the ECG waveform,and can correctly extract the location information of ECG signal feature point.Further more,this system can work stably and reliably.Main work and innovation point of this paper is as follows:(1)Each functional index of ECG signal acquisition system is determined on the basis of analysis and research of the mechanism of ECG signal from the human body.(2)The overall design of ECG signal acquisition system is determined,such as the system composition of the various modules and each functional index of the modules.(3)Based on AD620 instrumentation amplifier,TLC1549 A/D conversion chip,and AT89C51 MCU,the ECG signal acquisition hardware circuit is designed,including amplifier circuit,filter circuit,A/D converting and MCU controlling circuit,etc.The ECG data is extracted and controlled by MCU.(4)The design of the interface circuit,using MAX232 serial communication chip,realizes the the serial communication between the output of MCU and the receives of upper machine(PC).(5)The processing of PC ECG data and the design of analysis program,based on the Lab VIEW software programming,realizes the processing of ECG signal,display and some basic analysis,including filtering baseline drift,eliminating the broadband noise,position detection and analysis of R wave,position detection and analysis of QRS wave,and detection and analysis of heart rate,etc.(6)Software debugging and verification operation.The correctness of this system is verified by the means of transferring MIT/BIH ECG database,which is internationally recognized and testing the human body sample respectively.