OBJECTIVE: The purpose of this study is to design a portable ECG monitoring system, which integrates up-to-date PDA and RF communication technology, and to acquire the subject's biomedical signal without any constraint.

METHODS: The developed system is composed of a transmitter and a receiver. The transmitter has a MCU (microcontroller), three-axial acceleration sensor, ECG amplifier and Zigbee communication controller. It has two types of transmission mode, which are total signal transmission mode and HR (heart rate)/SC (step count) transmission mode. The receiver has a MCU, Serial Communication IC, and Zigbee communication controller. It forwards the received data to PDA, where the data can be stored and displayed.

RESULTS: In total signal transmission mode, it can send data 60 packets per second whose transmission speed corresponds to 300 ECG samples and 60 acceleration samples. In HR/SC transmission mode, it can calculate heart rate from ECG data with 216 samples per second and step count from acceleration data and send a packet every cardiac cycle.

CONCLUSION: Using this device, a new method of remote monitoring both vital sign and activity is realized. A PDA-based wireless ECG system enables patients to be monitored during their daily living, without any constraints. Also, this method will reduce medical costs in the aged society.