| The electrocardiograph machine is a kind of heart disease diagnosis instrument, used to record heart activity generated in the process of physiological signals and provides electrocardiogram (ECG) to doctor to achieve the diagnosis goal. Since Willem Einthoven produced the first galvanometer in 1903, the ECG has developed for more than 100 years. With the living conditions improving, people pay more and more attention to health. As a result, it makes the health intensive care apparatus more popular and more widely used. Now ordinary families use electrocardiogram machine for health care is still in its infancy stage and electrocardiogram machine on the market operation is usually very complicated, most hospitals by use of electrocardiogram machine all need specially trained to use, all these are caused certain difficulties to the popularization and application of electrocardiogram machine. In order to tutelage cardiac health conditions conveniently, we are in need of electrocardiograph which is portable, economical and practical, so that we can discover and diagnose some disease even psychoanalyst early by self.The electrocardiograph hardware system is based on ATmega64 digital signal processor which works as kernel control chip. Use a specialized instrumentation amplifier AD620A, high speed A/D converter AD7677AST and multi-channel analog switch CD4051 to design. The computer application programmed with the American national instrument Co., LTD (Nation Instruments, known as NI) launched a special set of in the development of virtual instrument design development platform-Lab VIEW to design. According to the characteristic of human's ECG signal, an excellent ECG signal sampling system was designed. The processing of the ECG signal includes data acquisition, data digital filter and wave analysis, it is a complicated process to automatically analyze electrocardiogram, and now this analysis is not consummate, because doctors must participate in this work.System is made up of two parts of hardware and software. Hardware part includes ECG signal receive, enlarge and filter circuit and gather circuit two parts among them. Analog circuit design includes lead wire input to snubber circuit, design of shielded wire drive and right-leg-driven circuit, design of ECG preamplifier circuit, design of lead switching circuit, design of band pass filter circuit, design of anti-interference and EMG interference circuit and design of main amplifier and electrical level lifting circuit; Digital circuit design includes design of ADC circuit, design of Single Chip Microcomputer (SCM) circuit and design of communication circuit. Software part includes lower computer data acquisition system design, PC software design and the design of digital filtering arithmetic.The hardware function need to be achieved is that:Gather ECG signal of the human body through electrode, through enlarge circuit change signal that can be discerned, then through collecting card convert analog signal to digital signal, and last, send them into computer. For the follow-up treatment, the ECG data can be transmitted to Personal Computer by serial RS232 interface.The software function need to be achieved is that:Realize the acquisition part of ECG waveform, realize the communication between lower computer and host computer, use the software design filtering method to eliminate the baseline drift ECG signal, ECG waveform can be designed by the computer screen to display directly on the working interface.The design extracted the weak ECG signal through hardware circuit, upload them on the host computer, realized the real-time data acquisition and display of ECG signal. By computer strong function to analyze ECG signal for medical diagnosis, it can provide reliable and valid data. |
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