A New Method for Synchronizing the Time of Networked Computers

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This project addresses the design and testing of a system for improving time dissemination on computer networks. The system consists of two parts: 1) servers whose clocks are calibrated using dial-up telephone links to the NIST primary time scale, and 2) clients who request calibration data from the servers via either a local- or wide-area network. The servers and clients construct models of the performance of the local clock and the calibration channel, and use these models to adjust the local time and the interval between calibrations to maintain a specified accuracy. The Internet is being used to compare the performance of the method with other systems. The method is simpler and potentially more accurate than the existing Network TIme Protocol because: 1) there can be many more primary servers since they require no special hardware. The network distance between any client and a primary server therefore can be quite short. 2) The channel between NIST and each primary server is easier to characterize because it is stable and reciprocal to a high degree. The result is either less frequent calibrations for the same level of accuracy or improved performance at the same calibration interval.