Methods for determining the frequency or period of a signal

Abstract

Methods for determining timestamps for signal timing edges for use in, e.g., a reciprocal counter for determining the frequency of a signal is disclosed, comprising the steps of inputting the signal into a tapped delay line, producing a plurality of delay line tap signals at the output of each of the delay line taps. In one embodiment, after detecting the signal timing edge and determining an initial time value corresponding to the timer clock cycle count at the signal timing edge or the next clock timing edge, the delay line tap signals are monitored to determine a fractional correction time value adjustment to be made to the initial value to account for the delay between the signal timing edge and the next clock timing edge to determine the timestamp. In another embodiment, after detecting the signal timing edge, the average of a plurality of delay line timer clock cycle counts corresponding to the timer clock cycle counts at the delay line tap signal timing edges is used to determine the timestamp.