Research On Anti-noise Portable ECG Monitor

In the military war and training, athletes training, medical treatment and other fields,sudden death and other accidents always happen because the body meet the humanphysiological limit. In order to prevent and reduce the casualties timely, real-timemonitoring of vital signs on person is very necessary. ECG(Electrocardiograph) is animportant warrant for diagnosing heart disease, but ECG monitorings on the market havesome disadvantages, such as the ability of anti-noise is poor and it cann’t monitor and alarmin real-time, which resulting the ECG monitorings cann’t work in the movement for longtimes. Therefore, the paper design a portable ECG tester based on ATmega16and a portableECG monitor based onARM9to solve these problems.The portable ECG tester based on ATmega16uses three leads way to get ECG signals.Firstly, we use a AD620chip to subtract these two exercise ECG signals and amplify it,getting the ECG signals containing big noise preliminary, because the frequency range ofECG signal is0.03Hz-100Hz, we use a second-order low-pass filter circuit and asecond-order high-pass filter circuit to get a better denoising ECG waveform. Becausesingle chip microcomputer can only process positive voltage, so we need to a voltage liftcircuit to make a voltage rise. Then, ATmega16single chip microcomputer is used tochange the analog signals into digital signals and output the digital signals via a serial port,MAX232chip converts TTL level to RS232level which is benefit to long-distancetransmission, then we use a wireless module to send it. Finally, the computer terminalreceive and store the real-time ECG signals through Labview and we use Matlab softwareto denoise it aided with wavelet transform. Then, we can calculate the heart rate, QRSinterval, QT interval and analyse them to judge if we have a cardiac abnormalities.The portable ECG tester have some disadvantages, such as, the clock is slow, theability to resist the movement interference is poor and it can not monitoring in real-time ect.To solve these problems, this paper design a portable ECG monitor based on ARM9. Firstly,we use three leads way to get two human exercise ECG signals of eight seconds separately,after denoising it with hardware circuit, we put them into a ARM chip. Then, these two ECG signals are disposed with wavelet transform to remove the baseline drift separately,then we use independent component analysis to make a further denoising to get a betterECG waveform. Finally, we can calculate the heart rate, QRS interval, QT interval andanalyse them to judge if we have a cardiac abnormalities. If the heart is abnormal, the ECGmonitor can activate the buzzer alarm device and send the abnormal ECG waveforms to thecomputer terminal, it is convenient for us to make further analysis and diagnosis. If theheart is normal, the monitor will collect next eight seconds exercise ECG signals to analyse.It is proved through analysis that this monitor have quick signal processing speed, stronganti-interference ability and real-time monitoring and alarming ability, which has greatpractical value.