Frequency measurement of a constant number of events with a fast circuit for the determination of the reciprocal value

摘要

A method and apparatus makes rapid frequency measurements by measuring time intervals for a series of blocks of event counts with the number of events in each block held constant. This makes the numerator of the events/time relationship constant so it does not have to be measured, processed or stored. The frequency of the signal is determined by measuring the time interval, then taking the inverse of the measured value and multiplying by the appropriate constant. A fast inverse circuit uses a Taylor series expansion technique implemented in digital circuit, with the slope resolution adjusted for regions of small slope to improve accuracy.