Impact of Wireless Interferences on ECG Signal Quality in Wearable Cardiac Monitoring Devices

Wireless interference in wearable ECG devices is a significant concern, as it can lead to inaccurate interpretations of cardiac signals in continuous monitoring applications. The objective is to experimentally investigate the impact of wireless interferences, such as Bluetooth and WiFi, on transmitting ECG signals in normal and diseased states. ECG signals generated using a hardware simulator are transmitted through a Bluetoothbased wireless channel and recorded in an electromagnetically shielded environment. The experimental setup comprises ten test cases that introduce wireless interference sources, including Bluetooth and WiFi sources at the receiver end. Time-domain analysis of recorded ECG signals for both normal and diseased states, demonstrated morphological distortions in recorded ECG amplitude and latency. Further, signal degradation is quantified using the Signal-to-Noise Ratio (SNR) and the results indicate that diseased states exhibit lower SNR compared to the normal state. This reduction occurs due to the non-linear and irregular morphological variations in diseased ECG signals, including phase shifts and amplitude fluctuations, which overlap with external wireless interferences, increasing their susceptibility to signal degradation. FFT-based spectral analysis is performed, to analyze frequency-specific distortions for normal and diseased states. The significant variations in peak magnitude with broader spectral distortions within the 0 to 50 Hz range are observed, particularly for test cases with multiple WiFi interference sources of high transmission power. These findings emphasize the impact of wireless interference on ECG signal quality, underscoring the significance of accurate disease identification in continuous cardiac monitoring systems.