Abstract: A system is disclosed for precisely measuring time intervals, used to either characterize or diminish noise components in repetitive waveforms. An interval timer generates a whole number count of cycles in combination with beginning and ending ramps capable of resolving fractions of a cycle, to accurately register the time interval. Selection logic can be implemented to time either single periods or spans of multiple consecutive periods of the waveforms. Multiple time measurements are arranged in sets, each set corresponding to a different span of “N” consecutive periods over a range of values for N. A variance of each set is generated, and an array of variance vs N provides a function having properties of an auto-correlation function. Instrument jitter can be reduced based on measurements of period spans rather than individual periods, and is reduced in proportion to the increasing size of the measured span.

Abstract: An event counter circuit including an input signal coupled to a frequency divider circuit that can be cleared by an external signal, a multiplexer coupled to the divider circuit driven by an output edge and its inverse, and a counter circuit coupled to the multiplexer driven by outputs of the multiplexer.

Abstract: A system is disclosed for precisely measuring time intervals, used to either characterize or diminish noise components in repetitive waveforms. An interval timer generates a whole number count of cycles in combination with beginning and ending ramps capable of resolving fractions of a cycle, to accurately register the time interval. Selection logic can be implemented to time either single periods or spans of multiple consecutive periods of the waveforms. Multiple time measurements are arranged in sets, each set corresponding to a different span of “N” consecutive periods over a range of values for N. A variance of each set is generated, and an array of variance vs N provides a function having properties of an auto-correlation function. Instrument jitter can be reduced based on measurements of period spans rather than individual periods, and is reduced in proportion to the increasing size of the measured span.