Improving the Performance Characteristics of PWLL

PWLL, the p-Wave Locked Loop, helps determining instantaneously the p to p time interval of the ECG and enables us to perform heart rate variability studies with p_p variation. In the previous PWLL circuit, the prefixed delay given for changing over from r-wave to p-wave might fail to work for certain abnormal p_p variations present in ECGs. In this improved version of the PWLL, the time duration for changing over to p_p is made dependent on p_p itself and locking is ensured for all types of p_p variations present in ECGs. Besides the improvement in locking features, improvements in other performance characteristics of the PWLL are proposed and analyzed. A nearly ideal PWLL is emulated and the responses of the practical PWLL and emulated PWLL are compared and analyzed as to help in reaching optimum hardware parameters. This performance improved PWLL would enable to ease further the heart rate variability studies.