Proposed Wireless ECG System

4 destination. When the ECG signal is transmitted, the transmitter will wait about milliseconds to complete the communication link. f communication link is ready, the transmitter will send the ECG signal to the receiver. n contrary, if the communication link is still not ready in allocated time, the transmitter will retry to establish the link up to times. Finally, following times when the transmitter is failed to establish the connection, the ECG signal transmission is aborted. The receiver consists of microcontroller and textile antenna. The receiver will receive the transmitted digital ECG data from the transmitter and display the ECG signals on a monitor. Microcontroller converts the digital ECG signals to serial analog data, and is then transferred to a computer via Arduino power cable. A free software is used for displaying the received ECG signals in real time.

3. Off‐Body Communication Experimental Test

n this research, we apply two investigations that are relating to the communication delay of the wireless system. We have actually conducted two kinds of measurement, those are on‐body communication and off‐body communication tests, in which each measurement has three different scenarios. When measurement is conducted, the subjects volunteers need to keep holding his position up to five minutes while recording the ECG data. Sometimes, when the subject moves around while the recording, noise appears on ECG signals. Subjects are two healthy males with skinny and fatty years old. The measurement is conducted in sitting condition of the subjects and the textile antenna is placed at the left arm of the subjects. By varying location distance and obstacle environment, the ECG signals are recorded in real time. n order to validate the system performance, the recorded ECG from the proposed system will be numerically compared with the clinical test at clinical healthcare on the same subjects. The following section will discuss each measurement scenario. 3.1. Scenario 1 n scenario , the transmitting Tx and receiving Rx antennas are situated at the left arm of the subjects, subject as Tx and subject as Rx. Subject and subject are situated in the same room at the th floor of the ‐storey concrete building, described in Fig. . The room is equipped by several desks, chairs, small cable poles, and acrylic bulkhead. The transmitted ECG signal is wirelessly received by subject Rx antenna at about m of distance, which is shown in Fig. . The result show that the ECG signals can be well received at the receiver eventhough there is a bit amplitude fluctuation of QRS‐ wave peak. a b Figure . a Tx antenna is attached on subject ; b Rx antenna is attached on subject . 4 Figure . Received ECG signals that are displayed at the receiver for subject scenario . 3.2. Scenario 2 n scenario , the transmitting Tx and receiving Rx antennas are situated at the same as the scenario , however, subject and subject are separated in the different room at the th floor of the ‐storey concrete building. The rooms are separated by some acrylic bulkheads at ‐ m of the distance. This scenario is aimed to determine whether the proposed system can send the ECG signal across the obstacle. The transmitted ECG signal is wirelessly received by subject receiver as shown in Fig. . The result show that the ECG signals can be well received at the receiver. Figure . Received ECG signals that are displayed at the receiver for subject scenario . 3.3. Scenario 3 n scenario , the transmitting Tx and receiving Rx antennas are situated at the same as the scenario , but the room of subject is equipped by some microwave mesurement tools, from which some radiation disturbance may exist. This scenario is aimed to verify the signal distortion may occur to ECG data reading due to electromagnetic interference. As a result, the received ECG signals are still well received, as depicted in Fig. . 0. 1 1. 2 2. 0. 01 0. 21 0. 49 0. 77 1. 1. 3 1. 1. 9 2. 2 2. 2. 8 3. 1 3. 4 3. 7 4. 4. 3 4. Amp litud e mV Elapsed time s Received ECG Signal 0. 1 1. 2 0. 11 0.3 0.49 0.7 0.8 1.0 1.2 1.4 1. 1.8 2.0 2.2 2.4 2. 2.8 3.0 3.2 Amplit ude mV Elapsed time s Received ECG Signal