Design and implementation of a multi-node wifi heart rate variability analysis system

This paper has designed a kind of WIFI multi-node heart rate variability (HRV) analysis system, consisting of several ElectroCardioGram (ECG) acquisition nodes and an analysis platform based on ARM Cortex-A8 processor. The node oversamples ECG signal through a photoelectric ear clip and filters it with FIR window before sending it to the platform with specific format package by WIFI module. The platform extracts ECG signal of each node from the received packages in real time and RR intervals are acquired from ECG signal by differential threshold algorithm so as to calculate time domain parameters. Before performing frequency domain analysis on RR intervals, the baseline wander is removed from RR intervals by db6 wavelet and RR intervals is resampled by cubic spline interpolation. All algorithm for each node can be done in short period by means of multi-thread and NEON technique. The system is promising for multi-node with real-time and stable operation and accurate analysis result, which can be widely used in medical care, the collective movement training and psychological testing.