Abstract: A master (virtual) clock is situated at a central data gathering station, and slave (physical) clocks are situated at one or more (functionally or spatially) remote stations. Time signals are exchanged between the master clock at the central station and each slave clock at each corresponding remote station. From these signals (i) the ratio between the frequencies of the central station master clock and the corresponding remote station slave clock is determined, (ii) the difference in reference (starting) time value between the central station master clock and the corresponding remote station slave clock is determined, and (iii) the transmission time between the central station master clock and the corresponding remote station slave clock is determined. Averages of the clock ratio, reference time, and transmission time are determined across successive time signals to provide improved accuracy.

Abstract: A master clock is situated at a central data gathering station, and slave clocks are situated at one or more (functionally or spatially) remote stations. Time signals are exchanged between the master clock at the central station and each slave clock at the corresponding remote station. From these signals (i) the transmission time between the central station and the corresponding remote station is determined, and (ii) the ratio between the frequencies of the central station master clock and the corresponding remote station slave clock is determined. The transmission time and clock ratio so determined are averaged between successive determinations to provide improved accuracy. The transmission time value is used to set the slave clock to a reference value accurately corresponding to the time kept by the master clock; and thereafter the clock ratio value is used to insure that the slave clock is incremented at a rate corresponding to the frequency of the oscillator in the master clock.