The Design Of A Portable ECG Detecting System

With the rapid development of economic globalization, people’s living standards continue to improve. And it makes people pay more attention to their own health due to the living pressures. Heart disease as a common disease in life has received more attention. There are many detection methods for heart disease, such as ECG, echocardiography, and X-rays, etc. Among these methods, ECG is the most common detection technique in hospital since it’s simple, convenient, and inexpensive. However, the accuracy of the detection results is mainly determined by doctors’ experiences. In this paper, a portable ECG detection system is designed for the rapid detection of ECG signals. It can collect human ECG signals real-time and give the detection result to the tester whether it is normal or not eventually after handling and analyzing the ECG signals. The system can be divided into two parts:hardware and software Details are as follows:(1) The design of front-end hardware circuit:ECG is a kind of faint signal, which is very susceptible to interference noise during the acquisition process. The main role of front-end hardware circuit is to amplify ECG and filter out any interference. ECG can be amplified 1000 times by AD620 and OPA227. The trap circuit is the major part of the filter circuit design. It is priority to the design of power frequency trap circuit in order to filter out the power interference which has great impact on ECG. For better filtering effect the system is designed with F42N50 chip which is better than double T and Fliege trap. In order to insure the safety of human, each circuit in the front-end hardware circuit which connected with human body should be in series with a large resistance to reduce the electric current flows through the human body.(2) The design of microprocessor:In order to reduce power consumption of the system and make the data transmission convenient, MSP430F5529, a microprocessor with low power consumption and supporting USB2.0 function module is chosen for the system. The main function of the microprocessor is to achieve A/D conversion, real-time processing of the signal and USB communication with the device.(3) The design of Bluetooth module:In order to achieve a portable system, we built the Bluetooth module on the basis of HC-05 Bluetooth module and UART function module of microprocessor. It increase the way of data transmission such as data transmission between Bluetooth module and mobile phone or computer.(4) The ECG feature extraction and classification:In order to acquire the ECG, we preliminarily discuss the effectiveness of using bispectrum estimation or topology as a feature extraction method in the paper. By using the extracted ECG eigenvector and single class classifier KNN we are able to detect abnormal ECG signal from the normal ECG signal.(5) The test of system:In order to verify the correctness of each part in the system, we have a function test for each part of the hardware and software. And the system test platform mainly consists of MATALB and LabVIEW.It is obvious that this system can realize all the predefined functions effectively by the systemic testing, such as collecting the ECG signals, handling and transmitting data, and estimating whether the ECG is normal. The system basically builds the framework of ECG anomaly detection system and provides some basic ideas for the development of the abnormal ECG detection. In addition, it will be useful for further development and application of the similar kind of devices after further improving the hardware and software of the system.