Study On ECG And Cardio-impedance Joint-measuring System Based On ARM

Development of the society makes a better people’s living standards, but in contrast,it is increasing side effects of humanity itself, one of which is the increasing year by yearincidence of cardiovascular diseases. Not only dose cardiac electrical signals go with thechange of the cardiac cycle, but the cardio-impedance signal can also reflect people’scardiac function of related information. Combining both to acquire the cardiac signal,which can lead final effect a more comprehensive result than acquiring single electricalor impedance signals, also can the data reflect cardiac function of the human body.This article, which aims at the way of the joint acquiring the cardio-electric signaland the cardio-impedance signal, is based on the generalization and characteristics of thebasic principle of the two signals, and designs the each of related signal acquisitioncircuit. First, based on the characteristics of ECG signal, the design uses AD8220andAD8618two kinds of chips as a pre-conditioning circuit to make use of the effect ofearly amplification and filtering of the signal and AD7685chip to process the ADconversion of the obtained voltage signal. According to the characteristics of thecardio-impedance signal, the AD5933chips will be the main chip of collecting signal;Releasing of50KHz,2V p-p voltage source on the human body, and give the collectionof the cardio-impedance signal an early amplification filtered by the AD8606, then theamplified signal is transferred to the AD5933to make a series of transformationsincluding AD conversion. S3C2440processor, which ARM920T kernel architecture asthe core inside, makes two-way signal data processing, the resulting data are sent tocomputer via a serial port of Max232, finally ECG signal and cardio-impedance signalwill be real-time display on the basis of output waveform.Compared to the characteristics of the design in the past, not only ECG andcardio-impedance signal to test the human cardiac-parameters commonly, but to thecollected signals’ high-precision, high-accuracy, real-time display effect is good.Compared to the cardiac diagnosis and treatment instrument in the market today, the design added character of low-cost, low-consumption and high-portability, which issignificant to equipment of main cardiac-parameter detection.