Study Of Heart Sound Wireless Transmission System Based On Bluetooth Technique

Cardiac auscultation is widely used to evaluate cardiac function in patients. Since heart sounds are generally of low frequency component and very faint, this method, depending on doctor's knowledge and experience, is subjective and sometimes is unreliable and ineffective. Recently it has been shown that the phonocariogram can be used for cardiac performance assessment. Specifically, it can be demonstrated that changes in the amplitude of the first heart sound correlate with changes in the maximum rate of rise of left ventricular pressure, a common measure of cardiac contractility. But general phonocardiogram analysis instrument only can monitor the static patient's short-time heart sound, and can't monitor the patient's long-time heart sound in various states. Therefore, development of phonocardiogram analysis instrument is very important to study the regularity of real-time heart sound and analyze the cardiac contractility variability in various states.Heart sound measure can only provide raw data for analysis, and the quality of these data can strongly influence the accuracy of heart sound analysis. Therefore, a sampling and wireless transmittion system of heart sound based on Bluetooth technique is implemented. It will expand clinical measure applications from static to dynamical environment and can study Cardiac Contractility Variability in different status.Bluetooth technique has many special significant adventages compared with other wireless techniques. The thesis answerd why choose Bluetooth.Since bluetooth technology has been promoted by SIG (Special Interest Group) in 1998, more and more bluetooth products emerged in the world. We expanded the application area of bluetooth in medical data acquirement and wireless communication because of the good features of bluetooth, such as functional agility, high-speed transmit-receive, cheaper and in general purpose.This thesis discussed how to realize the bluetooth data transmit-receive. In view of the features of heart sound signals, the module of data acquirement, the stack of bluetooth communication protocol and the interface of HCI (Host Controller Interface) were analyzed, and then the hardware and software of this bluetooth system were designed. Furthermore, there is briefly introduction of bluetooth protocol. Then the method of development Bluetooth module drivers and applications based on Windows Operating System were introduced, and the source codes were listed. Finally, the designs of hardware and software were described.The tests show that system has fast and exact features through the wireless channel built by Bluetooth in 10 meters radius. In the system real-time display of the received heart sound curve diagram can be achieved dynamically. Compared with wire communication, Bluetooth channel shows a little transmition delay, which is caused by serial data, but would not give any bad influence to main functions of system, such as heart sound recognition and real-time display.