Numerical Display of Pulse Repetition Rate Requires only Two Pulses

Abstract

Numerical display of pulse repetition rates is normally achieved by counting the number of waveform cycles that occur during a known interval (say 1 sec.) and displaying the final count in a read-out device (cold cathode tubes, LEDs, etc.). This method presupposes the presence of the waveform during the entire interval of counting. Also, the read-out is subject to the ± 1 count error. For low repetition rate waveforms (such as those encountered in heart-beat monitoring instruments), the counting rate has to be very large to get a satisfactory accuracy. The counter described in this article overcomes the above difficulties by measuring the waveform interval and inverting it to enable a direct numerical read-out of the repetition rates up to 10000.