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.

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.

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.

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.