- Automated real-time signal processing. the investigators will develop signal processing software to automatically eliminate noise, such as that generated by muscle contraction, electrical appliances, body motion, respiration, and radiofrequency signals. The remaining signals are then processed to separately display in real time to provide health care providers a new method to instantly estimate sympathetic tone. The ECG signals are used for automated arrhythmia detection while the SNA signals are available for risk stratification. This approach allows us to improve and broaden the clinical application of Einthoven's original invention by simultaneous detecting ECG and SNA from the skin.