Time Scales and Time Keeping in the 21 st Century
|
|
- Howard Ramsey
- 6 years ago
- Views:
Transcription
1 Time Scales and Time Keeping in the 21 st Century Peter Whibberley NPL Time & Frequency User Club 3 December 2008
2 Overview How we got where we are from GMT to UTC How UTC is produced Dissemination of UTC Future developments 2
3 Astronomers time Based on Sun s movement across the sky GMT is mean solar time on the Greenwich meridian clock time adjusted to keep in step with the Sun The second is 1/86400 of mean solar day 3
4 Greenwich Mean Time > Universal Time 1884 GMT adopted as worldwide reference Prime meridian at Greenwich Time zone system adopted 1928 IAU adopted the name Universal Time to designate the mean solar day starting at Greenwich mean midnight The term GMT remained in use in some countries 4
5 Earth rotation 1940s evidence for variations in Earth s rotation Plot shows excess length of day (LOD) Source USNO: 5
6 UT1 Several versions of Universal Time introduced: UT0 is observed mean solar time UT1 is UT0 corrected for polar wander UT2 is UT1 corrected for seasonal variations UT1 provides the most useful form of mean solar time Since 2003, UT1 has been a measure of Earth rotation angle Used by navigators, astronomers and Earth scientists UT1 is determined and published by the International Earth Rotation and Reference Systems Service (IERS) UT1 plays an important part in UTC 6
7 Atomic time First caesium clock operational at NPL in 1955 Wednesday, 24 December
8 The atomic second Frequency of NPL caesium standard compared with second of Ephemeris Time (ET) determined by US Naval Observatory Measurements led to re-definition of the second in 1967: The second is the duration of periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom. 8
9 International atomic time More caesium clocks developed NBS (USA), ON (Switzerland), etc Combined atomic time scale begins International Atomic Time (TAI) (UT TAI) ~ 0 on 1 January 1958 Scale interval is the SI second at mean sea level Conventionally counted using hh:mm:ss Not regarded by BIPM as a disseminated time scale 9
10 Coordinated Universal Time (UTC) UTC originated ~1960 as reference time scale coordinated between countries operating broadcast time signals Name formally adopted ~1967 UTC provides a time scale with stability of atomic clocks but steered to UT UTC forms the basis of civil timekeeping world-wide UTC defined in ITU-R Recommendation TF
11 How UTC is formed Computed by the Bureau International des Poids et Mesures (BIPM), Paris Based on 3 types of data: Time transfer measurements between the BIPM and realisations of UTC (known as UTC(k)) at ~60 institutes Offset measurements between each UTC(k) and other clocks in that institute or country, ~260 clocks in total contributing Realisations of the SI second by primary frequency standards Processing is carried out in monthly blocks The results are published in BIPM Circular T 11
12 Institutes contributing to UTC Source BIPM: 12
13 Local UTC(k) time scales International time BIPM Wednesday, 24 December 2008 ~260 commercial atomic clocks Free Atomic Time (EAL) IERS Primary Frequency Standards (PFS) National Timing Institutes calibrations International Atomic Time (TAI) Coordinated Universal Time (UTC) leap seconds Earth rotation measurements Universal Time (UT1) corrections to local UTC time scales BIPM Circular T 13
14 Steering UTC to UT Since 1 January 1972: (UTC TAI) is integer number of SI seconds Leap second adjustments are applied to UTC to keep UT1 UTC < 0.9 s The International Earth Rotation and Reference Systems Service (IERS): Monitors Earth rotation data (VLBI, GPS, SLR) Announces in Bulletin C whether a leap second is required at the end of the following December or June, ~ 6 months in advance 14
15 Leap seconds Current offset is TAI UTC = 33 s All leap seconds so far have been positive Next leap second will be applied to UTC at end of Positive leap second insertion: 23:59:57 23:59:58 23:59:59 =>23:59:60 00:00:00 00:00:01 15
16 UT1 - UTC Source IERS: 16
17 BIPM Circular T CIRCULAR T 249 ISSN OCTOBER 10, 12h UTC BUREAU INTERNATIONAL DES POIDS ET MESURES ORGANISATION INTERGOUVERNEMENTALE DE LA CONVENTION DU METRE PAVILLON DE BRETEUIL F SEVRES CEDEX TEL FAX tai@bipm.org 1 - Coordinated Universal Time UTC and its local realizations UTC(k). Computed values of [UTC-UTC(k)] and uncertainties valid for the period of this Circular. From 2006 January 1, 0h UTC, TAI-UTC = 33 s. From 2009 January 1, 0h UTC, TAI-UTC = 34 s. Date h UTC AUG 31 SEP 5 SEP 10 SEP 15 SEP 20 SEP 25 SEP 30 Uncertainty/ns Notes MJD ua ub u Laboratory k [UTC-UTC(k)]/ns AUS (Sydney) BIRM (Beijing) DLR (Oberpfaffenhofen) IT (Torino) NIST (Boulder) NMIJ (Tsukuba) NPL (Teddington) SIQ (Ljubljana) SU (Moskva) USNO (Washington DC) VMI (Ha Noi) Available from: 17
18 UTC(k) offsets from UTC 18
19 Properties of UTC Not available in real time Latency of days Traceability is via one of the ~60 UTC(k) Provides the reference for ALL civil and broadcast time scales, eg: GPS Time (via UTC(USNO)) Internet time protocols, eg. NTP Radio time signals, eg. MSF, DCF77, WWVB Speaking clock Provides an approximation to Universal Time To within 1 s offset UTC sometimes incorrectly called GMT 19
20 The future of UTC (1) Proposals to cease applying leap seconds to UTC being debated in ITU-R WP 7A Issue first raised in 1999 International conference held in Turin in 2003 Recommended long implementation period Recommended new name: International Time (TI) No overall consensus Only 2 options currently being considered: Continue the present system Apply no further leap seconds to UTC after a specified date 20
21 The future of UTC (2) Arguments for the change: Leap seconds require manual intervention Computer systems have difficulty coping with an additional second Current situation is resulting in proliferation of time scales without leap seconds Arguments against the change: Problems identified are relatively minor Equipment problems are amenable to technical solutions Present system works so no urgency to change Debate is currently deadlocked UK, China opposed to change at present BIPM and several other countries in favour 21
22 Improvements to UTC Expect steady improvement in stability More H-masers contributing, in better environments Improvements to time transfer links More rapid processing Incorporation of optical frequency standards Next generation of primary frequency standards Optical frequency & time transfer methods: fibre, laser link (T2L2) Future re-definition of the SI second? 22
23 Summary UTC is the reference time scale in use world-wide UTC provides the stability of atomic time (SI second) and a realisation of Earth rotation time (UT1) Access to UTC is through disseminated time signals linked to UTC through the national time scales UTC(k) 23
The future of UTC a British perspective
The future of UTC a British perspective Peter Whibberley ITU/BIPM Workshop on the Future of the International Time Scale 19 September 2013 Aims of the talk The importance of UTC How UK policy on the future
More informationRealization and maintenance of UTC
Realization and maintenance of UTC Elisa Felicitas Arias Director BIPM Time Department ITU/BIPM Workshop on the future of the international time scale Geneva, 19-20 September 2013 Outline Responsibilities
More informationIssues and Challenges Facing Traceable Accurate Time Delivery
Issues and Challenges Facing Traceable Accurate Time Delivery Anthony Flavin, MIET Chronos Technology Ltd ITSF, Prague, November 1 st 2016 Session 2 Chronos Technology: COMPANY PROPRIETARY V1.0 7-9-2106
More informationTHE FUTURE OF THE UTC TIME SCALE
THE FUTURE OF THE UTC TIME SCALE 20 th Meeting of the CCTF 18 September 2015 R.L. Beard Chairman, ITU-R Working Party 7A The Future of The UTC Time Scale Question ITU-R 236/7 (2000) 1. What are the requirements
More informationSPECIAL COLLOQUIUM ON THE FUTURE OF THE UTC TIME SCALE
SPECIAL COLLOQUIUM ON THE FUTURE OF THE UTC TIME SCALE 28-30 May 2003 Istituto Elettrotecnico Nazionale Galileo Ferraris Conference Hall Strada delle Cacce, 91 Torino, (Italy) COLLOQUIUM ON UTC Purpose:
More informationWhat you need to know about GNSS leap seconds
What you need to know about GNSS leap seconds Testing to ensure GPS receivers keep track of leap seconds 1 The importance of time For many people, time is the ultimate paradigm. Financial markets, military
More informationTime. Computer Science and Engineering College of Engineering The Ohio State University. Lecture 37
Time Computer Science and Engineering College of Engineering The Ohio State University Lecture 37 Interval vs Point Different questions: How long did it take to run 5k? When is our final exam? Answering
More informationDiscussions on the future UTC in the International Astronomical Union
Discussions on the future UTC in the International Astronomical Union Mizuhiko Hosokawa* and IAU working group on redefinition of UTC * National Institute of Information and Communications Technology,
More informationDistributed Systems. Clock Synchronization: Physical Clocks. Paul Krzyzanowski
Distributed Systems Clock Synchronization: Physical Clocks Paul Krzyzanowski pxk@cs.rutgers.edu Except as otherwise noted, the content of this presentation is licensed under the Creative Commons Attribution
More informationReport on Rapid UTC (UTCr)
Report on Rapid UTC (UTCr) BIPM Time Department 20th CCTF Meeting 17-18 September 2015 Summary Rapid UTC project Characteristics of UTCr UTCr computation Comparisons between UTCr and UTC Rapid UTC project
More informationMiddleware and Distributed Systems. Time. Martin v. Löwis. Mittwoch, 22. Februar 12
Middleware and Distributed Systems Time Martin v. Löwis Time In Distributed Systems Time is important Timestamp of electronic commerce transactions Some distributed algorithms depend on global time (consistency,
More informationUSING THE NETWORK TIME PROTOCOL (NTP) TO TRANSMIT INTERNATIONAL ATOMIC TIME (TAI)
32nd Annual Precise Time and Time Interval (PTTI) Meeting USING THE NETWORK TIME PROTOCOL (NTP) TO TRANSMIT INTERNATIONAL ATOMIC TIME (TAI) Judah Levine Time and Frequency Division and JILA National Institute
More informationA USER S GUIDE TO THE NPL TELEPHONE TIME SERVICE
A USER S GUIDE TO THE NPL TELEPHONE TIME SERVICE Contents 1. NPL s Computer Time Services 2. How to use the NPL Telephone Time Service 3. Additional information about the service 4. Contacting NPL Appendix
More informationUTC Timekeeping in the Future
UTC Timekeeping in the Future P. Kenneth Seidelmann University of Virginia John H. Seago Analytical Graphics, Inc. Time Scales Mean Solar Time Universal Time (UT1) Ephemeris Time Interna8onal Atomic Time
More informationThe ISP Column A monthly column on things Internet. Protocol Basics: The Network Time Protocol. NTP, Time, and Timekeeping. March 2014 Geoff Huston
The ISP Column A monthly column on things Internet March 2014 Geoff Huston Protocol Basics: The Network Time Protocol Back at the end of June 2012 [0] there was a brief IT hiccup as the world adjusted
More informationBasic Device Management
This chapter contains the following sections: About, page 1 Licensing Requirements for, page 2 Default Settings for Basic Device Parameters, page 3 Changing the Device Hostname, page 3 Configuring the
More informationSynchronization Part 1. REK s adaptation of Claypool s adaptation of Tanenbaum s Distributed Systems Chapter 5
Synchronization Part 1 REK s adaptation of Claypool s adaptation of Tanenbaum s Distributed Systems Chapter 5 1 Outline! Clock Synchronization! Clock Synchronization Algorithms! Logical Clocks! Election
More informationA USER'S GUIDE TO THE NPL TELEPHONE TIME SERVICE
A USER'S GUIDE TO THE NPL TELEPHONE TIME SERVICE Contents 1. NPL's Computer Time Services 2. How to use the NPL Telephone Time Service 3. Additional information about the service 4. Contacting NPL Appendix
More informationThe Impact of Leap Seconds on Digital Time Services
The Impact of Leap Seconds on Digital Time Services Judah Levine Time and Frequency Division NIST Boulder, Colorado USA Jlevine@boulder.nist.gov Judah Levine, NIST, ITU-leapsec, 2013: 1 Outline of the
More informationDr. J. Bishop Ministry of Defence, London Chairman NATO Working Group on PT&F. Abstract
Report on NATO PTTI Dr. J. Bishop Ministry of Defence, London Chairman NATO Working Group on PT&F Abstract This paper covers the work of the NATO Working Group on precise time and frequency (AC302ISG4lWG4)
More informationEXPERIENCES OF LEAP SECOND ADJUSTMENT OPERATIONS AND QUESTIONNAIRES IN JAPAN
(Preprint) AAS 13-503 EXPERIENCES OF LEAP SECOND ADJUSTMENT OPERATIONS AND QUESTIONNAIRES IN JAPAN Yasuhiro Koyama, * Tsukasa Iwama, * Hiroyuki Ito, * Yuko Hanado, * and Mizuhiko Hosokawa * INTRODUCTION
More informationData elements and interchange formats Information interchange - Representation of dates and times Part 1: Basic rules. DIS stage.
Reference number of working document: ISO/TC 154 N Date: 2016-10-26 Reference number of document: ISO/DIS 8601-1 Committee identification: ISO/TC 154 Secretariat: SAC Data elements and interchange formats
More informationInternet Engineering Task Force (IETF) Category: Standards Track ISSN: March 2014
Internet Engineering Task Force (IETF) K. Gross Request for Comments: 7164 AVA Networks Updates: 3550 R. van Brandenburg Category: Standards Track TNO ISSN: 2070-1721 March 2014 Abstract RTP and Leap Seconds
More informationDETECTION OF OUTLIERS IN TWSTFT DATA USED IN TAI
DETECTION OF OUTLIERS IN TWSTFT DATA USED IN TAI A. Harmegnies, G. Panfilo, and E. F. Arias International Bureau of Weights and Measures (BIPM) Pavillon de Breteuil F-92312 Sèvres Cedex, France E-mail:
More informationPanel Discussion on Time Rollover Events and Leap Seconds
29th Annual Precise Time and Time Interval (PTTI) Meeting Panel Discussion on Time Rollover Events and Leap Seconds Judah Levine Time and Frequency Division National Institute of Standards and Technology
More informationTime Synchronization and Logical Clocks
Time Synchronization and Logical Clocks CS 240: Computing Systems and Concurrency Lecture 5 Mootaz Elnozahy Today 1. The need for time synchronization 2. Wall clock time synchronization 3. Logical Time
More informationThe BIPM in the International Standards and Conformance Infrastructure
Bureau International des Poids et Mesures The BIPM in the International Standards and Conformance Infrastructure with particular reference to economic value and impact Dr Barry Inglis President, CIPM APMP
More informationThe UTC Time Scale: Internet timing issues
The UTC Time Scale: Internet timing issues Judah Levine Time and Frequency Division NIST/Boulder Jlevine@boulder. @boulder.nist.gov Judah Levine, ITU-leapsec: 1 Focus is on time Time interval and frequency
More informationTime Stamping and its Standardization for NMI ( + Topic about the future of UTC)
Time Stamping and its Standardization for NMI ( + Topic about the future of UTC) National Institute of Information and Communications Technology (NICT), Japan Tsukasa Iwama 1.Time Stamping Service and
More informationComments on the Debate over the Proposal to Redefine UTC
Comments on the Debate over the Proposal to Redefine UTC Presented to the General Assembly of the International Union of Radio science (URSI) August 18, 2014 Beijing, China Dr. Demetrios Matsakis U.S.
More informationDATABASE FOR TA (PL) AND UTC (PL)
DATABASE FOR TA (PL) AND UTC (PL) M. Marszalec National Institute of Telecommunications (NIT), Warsaw, Poland ul. Szachowa 1, 04-894, Warszawa, Poland, Tel: 5128407, Fax: 5128492 time.itl@itl.waw.pl A.
More informationCURRENT TIME SCALES AND CHALLENGES: GPS 1999 WNRO AND THE YEAR 2000
CURRENT TIME SCALES AND CHALLENGES: GPS 1999 WNRO AND THE YEAR 2000 Item Type text; Proceedings Authors Claflin, Ray, III Publisher International Foundation for Telemetering Journal International Telemetering
More informationTime Accuracy in the 100G Datalogging Endpoint
Time Accuracy in the 100G Datalogging Endpoint Chris Osterloh Sr Principal Systems Engineer 2010, Itron Inc. All rights reserved. 1 Executive Summary 3 100G Datalogging Endpoint Time Basics 3 100G Datalogging
More informationLeap Second Event Preparedness FIA Market Technology Division. May 14, 2015
Leap Second Event Preparedness FIA Market Technology Division May 14, 2015 Today s Webinar The webinar will be recorded. The presentation will be available on the FIA website within the next 24 hours.
More informationSETTING UP AN NTP SERVER AT THE ROYAL OBSERVATORY OF BELGIUM
SETTING UP AN NTP SERVER AT THE ROYAL OBSERVATORY OF BELGIUM Fabian Roosbeek, Pascale Defraigne, and André Somerhausen Royal Observatory of Belgium Abstract This paper describes the setup of an NTP server
More informationTime Handling in Programming Language
CSE 237B Fall 2009 Time Handling in Programming Language Rajesh Gupta University of California, San Diego System Characteristics Complexity in function (and in size) Concurrent control of separate components
More informationUTC Timekeeping in the Future
UTC Timekeeping in the Future P. Kenneth Seidelmann * and John H. Seago Historically, civil timekeeping has been based on mean solar time. With the discovery that the rotation of the Earth was not perfectly
More informationSETTING UP AN NTP SERVER AT THE ROYAL OBSERVATORY OF BELGIUM
SETTING UP AN NTP SERVER AT THE ROYAL OBSERVATORY OF BELGIUM Fabian Roosbeek, Pascale Defraigne, and André Somerhausen Royal Observatory of Belgium Abstract This paper describes the setup of an NTP server
More informationTIME AND FREQUENCY ACTIVITIES AT THE LITHUANIAN NATIONAL TIME STANDARD LABORATORY
TIME AND FREQUENCY ACTIVITIES AT THE LITHUANIAN NATIONAL TIME STANDARD LABORATORY Rimantas Miškinis Time and Frequency Standard Laboratory Semiconductor Physics Institute/State Metrology Service A.Goštauto
More informationThe Network Computer as Precision Timekeeper
The Network Computer as Precision Timekeeper David L. Mills University of Delaware http://www.eecis.udel.edu/~mills mills@udel.edu alautun, Maya glyph 10-Jan-03 1 Introduction Network Time Protocol (NTP)
More information3.3 Analysis Coordinator
3.3 Analysis Coordinator 3.3 Analysis Coordinator 1. Introduction In this report we outline the activities of the Analysis Coordinator during 2011. The main activities were clarifying the distribution
More informationUpdate: Ethernet Time Transfer through a U.S. Commercial Optical Telecommunications Network ITSF 2016
Update: Ethernet Time Transfer through a U.S. Commercial Optical Telecommunications Network ITSF 2016 Marc Weiss, mweiss@nist.gov, 303-497-3261 NIST Time and Frequency Division Lee Cosart, lee.cosart@microsemi.com,
More informationTitle. Description. Syntax. stata.com. datetime translation String to numeric date translation functions
Title stata.com datetime translation String to numeric date translation functions Description Syntax Remarks and examples Also see Description These functions translate dates and times recorded as strings
More informationGSN SunShot Procedures Using Internet Solar Position Calculator
GSN SunShot Procedures Using Internet Solar Position Calculator Purpose: Determine astronomical (true) north for instrument orientation by observing the Sun s azimuth using a Theodolite and Sun Position
More informationGalileo Reference Centre. Peter BUIST (GSA), Alvaro Mozo (GSA), Hillar Tork (EC) EUREF SYMPOSIUM 2018, May 30 th, Amsterdam
Galileo Reference Centre Peter BUIST (GSA), Alvaro Mozo (GSA), Hillar Tork (EC) EUREF SYMPOSIUM 2018, May 30 th, Amsterdam EU GNSS programmes Political Oversight European Council and Parliament Programme
More informationPTTI 2030 TIME TRANSFER AND APPLICATIONS IN 2030
PTTI 2030 TIME TRANSFER AND APPLICATIONS IN 2030 Stephen Mitchell U.S. Naval Observatory Tel: +1 (202) 762-0740 stephen.mitchell@usno.navy.mil Jim Wright SLRSC Systems Engineering Tel: +1 (321) 494-1530
More informationRecommendation for Space Data System Standards TIME CODE FORMATS RECOMMENDED STANDARD CCSDS B-4
Recommendation for Space Data System Standards TIME CODE FORMATS RECOMMENDED STANDARD CCSDS 301.0-B-4 BLUE BOOK November 2010 Recommendation for Space Data System Standards TIME CODE FORMATS RECOMMENDED
More informationBSN 8X82-A1507 8X82 HANDY MANUAL. < English > Printed in Japan
BSN 8X82-A1507 8X82 HANDY MANUAL < English > Printed in Japan Please carefully read the instructions in this Complete User Guide before using the watch. For details, please read the 8X82 (GPS Solar) Complete
More informationPSL Power Standards Lab 2020 Challenger Drive Alameda, CA USA TEL FAX
Reading PQube Meters remotely using Modbus-over-TCP PSL Power Standards Lab 2020 Challenger Drive Alameda, CA 94501 USA TEL ++1-510-522-4400 FAX ++1-510-522-4455 www.powerstandards.com 1 October 2010 A
More informationDistributed Coordination 1/39
Distributed Coordination 1/39 Overview Synchronization of distributed processes requires new concepts in addition to synchronization of processes in single multi-core systems. Topics: Notion of global
More informationMain Options. Synchronisation source: Satellite (GPS) Terrestrial Low Frequency (MSF, DCF77, WWVB, etc) Timecode (IRIG, AFNOR, etc)
M210 Modular Timing System The M210 is a highly flexible timing system designed for use in any applications where reliable time information is required. It is ideal where synchronisation of different output
More informationAtomic Time Manager 400 Product Documentation
Atomic Time Manager 400 Product Documentation Version 1.2.3 March 24, 2004 Copyright 2003-2004, Client Server Development, Inc. and Davis Software Services, Inc. All Rights Reserved 1. Introduction...4
More informationTime in Distributed Systems
in Distributed Systems There is no common universal time (Einstein) but the speed of light is constant for all observers irrespective of their velocity event e2 at earth time t2 ---- large distances ----
More informationLast Class: Naming. DNS Implementation
Last Class: Naming Naming Distributed naming DNS LDAP Lecture 12, page 1 DNS Implementation An excerpt from the DNS database for the zone cs.vu.nl. Lecture 10, page 2 X.500 Directory Service OSI Standard
More information18-642: Time and Date
18-642: Time and Date 2/21/2018 Date and Time Anti-Patterns for Date and Time: Daylight savings time hard-coded Time kept without handling time problems Daylight savings time, time zones, mobility Internationalization
More informationBSN 8X53C-A1710 8X53 HANDY MANUAL. < English > PSX-5. Printed in Japan
BSN 8X53C-A7 8X53 HANDY MANUAL < English > PSX-5 Printed in Japan Please carefully read the instructions in this Complete User Guide before using the watch. For details, please read the 8X53C (GPS Solar)
More informationTCG 01-G & TCG 02-G Firmware Release Notes
TCG 01-G & TCG 02-G Firmware Release Notes VERSION F2.28r6 (May 2018) Bug: The sync relay was closing when the clock went into the state; Tuning. The operation has been changed and the relay will close
More informationCHARACTERISTICS OF TIME SYNCHRONIZATION RESPONSE OF NTP CLIENTS ON MS WINDOWS OS AND LINUX OS
CHARACTERISTICS OF TIME SYNCHRONIZATION RESPONSE OF NTP CLIENTS ON MS WINDOWS OS AND LINUX OS Katsuhisa Sato and Kazuyoshi Asari Mizusawa VERA Observatory National Astronomical Observatory of Japan Mizusawa,
More informationClock-Synchronisation
Chapter 2.7 Clock-Synchronisation 1 Content Introduction Physical Clocks - How to measure time? - Synchronisation - Cristian s Algorithm - Berkeley Algorithm - NTP / SNTP - PTP IEEE 1588 Logical Clocks
More informationKrontek KT2050 Network Clock Controller
Krontek KT2050 Network Clock Controller Slave Clock Controller - 1 - Rev 1.2 24-Nov-2008 Table of contents INTRODUCTION... 3 TIME CORRECTION FORMATS... 4 Communicating with the Controller... 5 Main Menu...
More informationSynchronization of Network Devices Time by GPS Based Network Time Protocol Output
Synchronization of Network Devices Time by GPS Based Network Time Protocol Output Ajay Rajput Department of Electronics & Communication Engineering Lord Krishna College of Technology, Indore, Madhya Pradesh,
More informationCan Digital Evidence Endure the Test of Time?
DIGITAL FORENSIC RESEARCH CONFERENCE By Michael Duren, Chet Hosmer Presented At The Digital Forensic Research Conference DFRWS 2002 USA Syracuse, NY (Aug 6 th - 9 th ) DFRWS is dedicated to the sharing
More informationSystems Programming/ C and UNIX
Systems Programming/ C and UNIX A. Fischer CSCI 4547/6647 What is Time? November 6, 2017 A. Fischer CSCI 4547/6647[1ex]What is Time? Systems Programming Lecture 8... 1/24 November 6, 2017 1 / 24 Outline
More informationEthernet Time Transfer through a U.S. Commercial Optical Telecommunications Network WSTS 2015
Ethernet Time Transfer through a U.S. Commercial Optical Telecommunications Network WSTS 2015 Marc Weiss, mweiss@nist.gov, 303-497-3261 NIST Time and Frequency Division Lee Cosart, lee.cosart@microsemi.com,
More information2. Time and Global States Page 1. University of Freiburg, Germany Department of Computer Science. Distributed Systems
2. Time and Global States Page 1 University of Freiburg, Germany Department of Computer Science Distributed Systems Chapter 3 Time and Global States Christian Schindelhauer 12. May 2014 2. Time and Global
More informationVerteilte Systeme (Distributed Systems)
Verteilte Systeme (Distributed Systems) Karl M. Göschka Karl.Goeschka@tuwien.ac.at http://www.infosys.tuwien.ac.at/teaching/courses/ VerteilteSysteme/ Lecture 6: Clocks and Agreement Synchronization of
More informationhshlib Data Overview
Harold S. Henry January 1, 2011 7511 329 th Avenue SE Fall City, WA 98024 harold@talerian.com hshlib Data Overview The hshlib distribution contains a portable static C-linkable library written by Harold
More informationCan Digital Evidence Endure the Test of Time?
DIGITAL FORENSIC RESEARCH CONFERENCE Can Digital Evidence Endure the Test of Time? By Michael Duren, Chet Hosmer From the proceedings of The Digital Forensic Research Conference DFRWS 2002 USA Syracuse,
More informationCCSDS Historical Document
CCSDS Historical Document This document s Historical status indicates that it is no longer current. It has either been replaced by a newer issue or withdrawn because it was deemed obsolete. Current CCSDS
More informationCALCONNECT DOCUMENT CD Mobile Calendar Interoperability Test Suite Version: 1.1 Date: MOBILE Technical Committee
CALCONNECT DOCUMENT CD 0706 Type: Recommendation Title: Mobile Calendar Interoperability Test Suite Version: 1.1 Date: 2008-08-24 Status: Published Source: MOBILE Technical Committee This document incorporates
More informationENHANCEMENTS TO TIME.GOV: THE NATIONAL WEB CLOCK FOR THE UNITED STATES
ENHANCEMENTS TO TIME.GOV: THE NATIONAL WEB CLOCK FOR THE UNITED STATES Andrew N. Novick National Institute of Standards and Technology 325 Broadway, Boulder, CO 80305, USA Tel: (303) 497-3378; E-mail:
More informationData Management. Data Quality and Time Synchronization. Gino Crispieri - ISMI
Data Management Data Quality and Time Synchronization Gino Crispieri - ISMI Advanced Materials Research Center, AMRC, International SEMATECH Manufacturing Initiative, and ISMI are servicemarks of SEMATECH,
More informationNews English.com Ready-to-use ESL / EFL Lessons 2005 was a second longer than usual
www.breaking News English.com Ready-to-use ESL / EFL Lessons The Breaking News English.com Resource Book 1,000 Ideas & Activities For Language Teachers http://www.breakingnewsenglish.com/book.html 2005
More informationA guide to reference standards in support of Quality Assurance requirements of GEO QA4EO-QAEO-GEN-DQK-003
A guide to reference standards in support of Quality Assurance requirements of QA4EO-QAEO-GEN-DQK-003 A guide to reference standards in support of Quality Assurance requirements of Author: E-mail: Nigel
More informationINRIM TIME AND FREQUENCY LABORATORY: A NEW DATA MANAGEMENT SYSTEM (DMS)
INRIM TIME AND FREQUENCY LABORATORY: A NEW DATA MANAGEMENT SYSTEM (DMS) Valerio Pettiti, Roberto Costa, Giancarlo Cerretto, Franco Cordara Istituto Nazionale di Ricerca Metrologica (INRiM), Turin, Italy
More informationCSE 5306 Distributed Systems. Synchronization
CSE 5306 Distributed Systems Synchronization 1 Synchronization An important issue in distributed system is how processes cooperate and synchronize with one another Cooperation is partially supported by
More informationSynchronization Network Migration with focus on coherent network Primary Reference Time Clocks (cnprtc)
Deutsche Telekom @ITSF2014 hronization Network Migration with focus on coherent network Primary Reference Time Clocks (cnprtc) Helmut Imlau, 4.11.2014 ITSF 2014: hronization Network Migration Steps with
More informationITRF2004 Strategy. Zuheir Altamimi Claude Boucher
ITRF2004 Strategy Requested Input data Status of submissions Strategy for Combination Datum Specifications Origin (Geocenter) Scale Orientation Time evolution (NNRC) Evaluation & Validation Zuheir Altamimi
More informationR ev D. Daylight Saving Time Configuration Guide for an RF Network
749233 R ev D Daylight Saving Time Configuration Guide for an RF Network Please Read Important Please read this entire guide. If this guide provides installation or operation instructions, give particular
More informationKrontek KT2010 Dual Circuit Krontek Signal Controller
Krontek KT2010 Dual Circuit Signal Controller 1 INTRODUCTION The Krontek KT2010 Signal Controller is a Programmable Controller with an autosensing 10/100Mbit Ethernet Interface. It provides two output
More informationNATIONAL TIME AND FREQUENCY STANDARD DISSEMINATION SYSTEM IN ICT ERA
NATIONAL TIME AND FREQUENCY STANDARD DISSEMINATION SYSTEM IN ICT ERA AKIHIKO MACHIZAWA, TSUKASA IWAMA, HARUO SAITO TADAHIRO GOTOH, HIROSHI TORIYAMA, MIZUHIKO HOSOKAWA National Institute of Information
More informationNew Topic: Naming. Approaches
New Topic: Naming Names are used to share resources, uniquely identify entities and refer to locations Need to map from name to the entity it refers to E.g., Browser access to www.cnn.com Use name resolution
More informationCSE 5306 Distributed Systems
CSE 5306 Distributed Systems Synchronization Jia Rao http://ranger.uta.edu/~jrao/ 1 Synchronization An important issue in distributed system is how process cooperate and synchronize with one another Cooperation
More informationEthernet Time Transfer through a U.S. Commercial Op9cal Telecommunica9ons Network WSTS 2016
Ethernet Time Transfer through a U.S. Commercial Op9cal Telecommunica9ons Network WSTS 2016 Marc Weiss, mweiss@nist.gov, 303-497- 3261 NIST Time and Frequency Division Lee Cosart, lee.cosart@microsemi.com,
More informationUniversity of Texas Center for Space Research ICESAT/GLAS Document: CSR SCF Release Notes for Orbit and Attitude Determination
University of Texas Center for Space Research ICESAT/GLAS Document: CSR SCF Notes for Orbit and Attitude Determination Tim Urban Sungkoo Bae Hyung-Jin Rim Charles Webb Sungpil Yoon Bob Schutz Version 3.0
More informationRadiocommunication Bureau (BR)
参考資料 2 Radiocommunication Bureau (BR) Circular Letter 3/LCCE/39 16 May 2017 To Administrations of Member States of the ITU, Radiocommunication Sector Members, ITU R Associates participating in the work
More informationAdvanced Topics in Distributed Systems. Dr. Ayman A. Abdel-Hamid. Computer Science Department Virginia Tech
Advanced Topics in Distributed Systems Dr. Ayman A. Abdel-Hamid Computer Science Department Virginia Tech Synchronization (Based on Ch6 in Distributed Systems: Principles and Paradigms, 2/E) Synchronization
More informationUNIT IV 1. What is meant by hardware and software clock? Clock devices can be programmed to generate interrupts at regular intervals in orders that, for example, time slicing can be implemented.the operating
More informationMin-IOP (Minimum Interoperable Subset) Use Cases Version: 1.1 Date:
CALCONNECT DOCUMENT CD 0601 Type: Recommendation Title: Min-IOP (Minimum Interoperable Subset) Use Cases Version: 1.1 Date: 2006-01-24 Status: Published Source: USECASE Technical Committee This document
More informationPTP650 Synchronous Ethernet and IEEE1588 Primer
PTP650 Synchronous and IEEE1588 Primer Table of Contents 3 in Cellular Backhaul 3 Timing Options for Cellular Backhaul 4 Synchronous 4 What is Synchronous? 4 Synchronous on PTP 650 5 Precision Time Protocol
More informationSES 123 Global and Regional Energy Lab Worksheet
SES 123 Global and Regional Energy Lab Worksheet Introduction An important aspect to understand about our planet is global temperatures, including spatial variations, such as between oceans and continents
More informationMobile Calendar Interoperability Test Suite
Title: Mobile Calendar Interoperability Test Suite Version: 1.0 Date: 28 August 2007 Contributed: Editors: Status: TC-Mobile Technical Committee Chris Dudding, Symbian Ltd Mark Paterson, Oracle Published
More informationSynchronization. Clock Synchronization
Synchronization Clock Synchronization Logical clocks Global state Election algorithms Mutual exclusion Distributed transactions 1 Clock Synchronization Time is counted based on tick Time judged by query
More informationFM300 Network Server
FM300 Network Server User s Manual March 2005 MEDA, Inc Macintyre Electronic Design Associates, Inc 43676 Trade Center Place, Suite 145 Dulles, VA 20166 Disclaimer of Warranty FM300 Network Server NO WARRANTIES
More informationF950 Abbreviated instruction
English This watch is solar-powered. Expose the dial to light and use it sufficiently charged. To see details of charging time, specifications and operations, refer to the instruction manual: F950 instruction
More information殷亚凤. Synchronization. Distributed Systems [6]
Synchronization Distributed Systems [6] 殷亚凤 Email: yafeng@nju.edu.cn Homepage: http://cs.nju.edu.cn/yafeng/ Room 301, Building of Computer Science and Technology Review Protocols Remote Procedure Call
More informationHigh Accuracy Time Synchronization over SpaceWire Networks - update
High Accuracy Time Synchronization over SpaceWire Networks - update Aeroflex Gaisler AB Kungsgatan 12, SE-41119 Göteborg, Sweden sales@gaisler.com +46 31 775 86 50 www.aeroflex.com/gaisler 1 Overview Standard
More informationSES 123 Global and Regional Energy Lab Procedures
SES 123 Global and Regional Energy Lab Procedures Introduction An important aspect to understand about our planet is global temperatures, including spatial variations, such as between oceans and continents
More informationGPS IIF yaw attitude control during eclipse season
GPS IIF yaw attitude control during eclipse season F. Dilssner, T. Springer, W. Enderle European Space Operations Centre (ESOC), Darmstadt, Germany AGU Fall Meeting, San Francisco Dec 9, 2011 GPS IIF yaw
More informationSuppliers' Information Note. BT International Megastream 155. Service Description
SIN 326 Issue 1.3 January 2016 Suppliers' Information Note For The BT Network BT International Megastream 155 Service Description Each SIN is the copyright of British Telecommunications plc. Reproduction
More information