A Cardiotachometer which Calculates Rate Digitally

A digital beat-to-beat and integrating cardiotachometer which calculates heart rate digitally in a simple manner has been constructed. The device needs no calibration and has an operating range from 1 to 999 beats/min with an accuracy of ±½ digit, and will calculate heart rate either on a beat-to-beat basis or averaged over 10, 20, or 50 beats.