The NIST automated computer-time service

Levine, Judah; Weiss, Marc; Davis, D. D.; Allan, David W.; Sullivan, Donald

doi:10.6028/jres.094.029

Cited by 36 publications

(18 citation statements)

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“…Because UTC(NIST) is a close real-time approximation of UTC, it can also be utilized as an official time source for financial exchanges throughout the world. NIST distributes UTC(NIST) to the general public through a variety of services that operate over various mediums including WWV, WWVH, and WWVB, which broadcast time signals via high frequency (HF) and low frequency (LF) radio signals [16,32]; by the Automated Computer Time Service (ACTS), which broadcasts time codes via ordinary telephone lines [33]; and by the Internet Time Service (ITS), which broadcasts billions (10 9 ) of time codes per day via the public Internet [17]. However, due to uncompensated propagation delays, each of these services delivers time to the user that is far less accurate than the time kept at NIST.…”

Section: Coordinated Universal Time (Utc) and Utc(nist)mentioning

confidence: 99%

Accurate, Traceable, and Verifiable Time Synchronization for World Financial Markets

Lombardi

Novick

Neville-Neil³

et al. 2016

J. RES. NATL. INST. STAN.

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The National Institute of Standards and Technology (NIST), through a collaboration with Perseus, a global provider of telecommunication services, is providing accurate, traceable, and verifiable time synchronization to stock exchanges in the United States, Europe, and Asia. The paper describes why accurate time is necessary for fair and equitable financial markets and summarizes current and proposed future synchronization requirements in the financial sector. We discuss reference time sources and provide a technical overview of how NIST transfers time to data center hosted stock exchange. We also discuss how Perseus distributes NIST time to financial market customers and describes how the time is verified. Measurement data are presented, along with a discussion of measurement uncertainty.

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Section: Coordinated Universal Time (Utc) and Utc(nist)mentioning

confidence: 99%

Accurate, Traceable, and Verifiable Time Synchronization for World Financial Markets

Lombardi

Novick

Neville-Neil³

et al. 2016

J. RES. NATL. INST. STAN.

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“…The method can be illustrated by considering the statistics of the telephone connections that are used to link the NIST time servers to the atomic clock ensemble [5][6]. A typical connection lasts about 30 s, and the statistics of these connections can be characterized as white phase noise for the duration of the connection, with the exception of the first few seconds during which the line delay is stabilizing.…”

Section: Synchronizing the Client System Clockmentioning

confidence: 99%

An Algorithm for Synchronizing a Clock When the Data Are Received Over a Network With an Unstable Delay

Levine

2016

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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A method is presented for synchronizing the time of a clock to a remote time standard when the channel connecting the two has significant delay variation that can be described only statistically. The method compares the Allan deviation of the channel fluctuations to the free-running stability of the local clock, and computes the optimum interval between requests based on one of three selectable requirements: (1) choosing the highest possible accuracy, (2) choosing the best tradeoff of cost vs. accuracy, or (3) minimizing the number of requests to realize a specific accuracy. Once the interval between requests is chosen, the final step is to steer the local clock based on the received data. A typical adjustment algorithm, which supports both the statistical considerations based on the Allan deviation comparison and the timely detection of errors is included as an example.

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“…The synchronization source for each server is shown by dissemination service if stratum 0 or 1 or by another server if higher. GPS, DCF77 and WWV use radio and satellite, ATOM is a national standard clock ensemble and ACTS is the Automated Computer Time Service operated by NIST [LEV89].…”

Section: Intersection Algorithmmentioning

confidence: 99%

Improved algorithms for synchronizing computer network clocks

Mills

1995

IEEE/ACM Trans. Networking

224

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The Network Time Protocol (NTP) is widely deployed in the Internet to synchronize computer clocks to each other and to international standards via telephone modem, radio and satellite. The protocols and algorithms have evolved over more than a decade to produce the present NTP Version 3 specification and implementations. Most of the estimated deployment of 100,000 NTP servers and clients enjoy synchronization to within a few tens of milliseconds in the Internet of today. This paper describes specific improvements developed for NTP Version 3 which have resulted in increased accuracy, stability and reliability in both local-area and wide-area networks. These include engineered refinements of several algorithms used to measure time differences between a local clock and a number of peer clocks in the network, as well as to select the best ensemble from among a set of peer clocks and combine their differences to produce a clock accuracy better than any in the ensemble. This paper also describes engineered refinements of the algorithms used to adjust the time and frequency of the local clock, which functions as a disciplined oscillator. The refinements provide automatic adjustment of message-exchange intervals in order to minimize network traffic between clients and busy servers while maintaining the best accuracy. Finally, this paper describes certain enhancements to the Unix operating system software in order to realize submillisecond accuracies with fast workstations and networks.

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The NIST automated computer-time service

Cited by 36 publications

References 0 publications

Accurate, Traceable, and Verifiable Time Synchronization for World Financial Markets

Accurate, Traceable, and Verifiable Time Synchronization for World Financial Markets

An Algorithm for Synchronizing a Clock When the Data Are Received Over a Network With an Unstable Delay

Improved algorithms for synchronizing computer network clocks

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