Method and circuitry for aligning the phase of high-speed clocks in telecommunications systems

Abstract From the Canadian patent

A method and circuitry are provided for detecting and measuring a phase difference between the output signals from a primary stratum clock and a standby stratum clock in a telecommunications system computing a, period of time needed for a numerically-controlled oscillator to shift the frequency of the standby clock enough to cancel the phase difference, transforming the required period of time into a signal representing a corresponding number of frequency shift steps and, controlling the numerically-controlled oscillator with the step signal to shift the frequency of the standby clock accordingly and thereby cancel the phase difference. Both the frequency and phase alignments of the two …