| 摘要 |
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. The clock ratio and reference time values are used to derive data referenced to the master clock at the central station from data collected via the slave clock at the remote stations so that the time and data values associated with the data correspond to time and data values generated by the master clock at the central station. If desired, a (virtual) master clock can be determined having time values which are the average of the master clock and all slave clock time values.
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