A New Method for Synchronizing the Time of Networked Computers

本项目涉及改进计算机网络上时间传播的系统的设计和测试。该系统由两部分组成：1)服务器，其时钟使用到NIST主时标的拨号电话链路进行校准；以及2)客户端，其通过局域网或广域网向服务器请求校准数据。服务器和客户端构建本地时钟和校准通道的性能模型，并使用这些模型来调整本地时间和校准之间的间隔，以保持指定的精度。互联网被用来比较该方法与其他系统的性能。该方法比现有的网络时间协议更简单，而且可能更准确，因为：1)可以有更多的主服务器，因为它们不需要特殊的硬件。因此，任何客户端和主服务器之间的网络距离可能非常短。2)NIST和各主服务器之间的通道更容易表征，因为它是稳定的和高度互惠的。其结果要么是在相同的精度水平下减少校准频率，要么是在相同的校准间隔下提高性能。

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.