Timing Standards in Australia

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Timing Standards in Australia

• Peter Fisk
• CSIRO National Measurement Laboratory
• Lindfield, Sydney

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The National Measurement Laboratory (NML)
Located in Lindfield, Sydney Role To support
the Australian National Measurement System by,
among other things, realising and maintaining
Australias standards for physical measurement,
as required by the National Measurement Act (1960)
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The NML Time and Frequency Group
Peter Fisk
Bruce Warrington
Anura Gajaweera
Stephen Quigg
Michael Wouters
Malcolm Lawn
John Thorn
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Atomic clock development
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Satellite time transfer research
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International Bureau of Weights and Measures

• Bureau Internationale des Poids et Mesures
  (BIPM)
• Peak body of the Metric System of Units
• Created in 1875
• Funded by contributions to the Member States
  of the Metre Treaty
• Located in Paris

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Organisation of the Metric System of Units
Consultative Committee for Time and Frequency
BIPM
International Committee for Weights and Measures
Consultative Committee for Temperature
Metric System of Units
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History of the definition of the second
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NMLs Clock Array
Sydney 4 Cesium clocks and 2 Hydrogen
Masers Melbourne 1 Cesium clock (NTP Service,
calibration service) Perth 1 Rubidium
clock (NTP service)
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Coordinated Universal Time (UTC)An average of
many clocks
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Dissemination of UTC - BIPM Circular T
ISSN 1143-1393
Circular T 146 (2000 March 20)

Circulaire T 146
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- Coordinated Universal Time UTC. Computed values
of UTC-UTC(k).

(From 1999 January 1, 0h UTC, TAI-UTC 32 s)


Date 2000 0h UTC Jan 31
Feb 5 Feb 10 Feb 15 MJD
51574 51579 51584
51589 Laboratory k
UTC-UTC(k) (Unit is one nanosecond)

AOS (Borowiec)
-14118 -14420 -14619 -14801
APL (Laurel) - 5272
5303 5331 AUS (Sydney)
834 839 837 835
BEV (Wien) -49
-56 -64 -70 BIRM (Beijing)
-15833 -15852 -15898
-15982 CAO (Cagliari)
-3520 -3507 -3504 -3516 CH
(Bern) 165 171
167 154 CNM (Queretaro)
-33 -29 -33 -29
CRL (Tokyo) -191
-202 -218 -232 CSAO (Lintong)
-7 -16 -7
-5 CSIR (Pretoria) 2269
2201 2162 2124 DLR
(Oberpfaffenhofen) -5475 -5637
-5805 -5971
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Principle of Common-View Time Transfer
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Principle of GPS Common-View Time Transfer

• Satellite transmits
• Timing pulses
• Orbital data

GPS Satellite
Timing Pulse
Lab 2
Lab 1
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What is GPS Time ?
GPS Satellites
GPS Master Control Centre
GPS Time UTC(USNO) 40 ns (no leap secs)
UTC(USNO)
United States Naval Observatory (USNO)
UTC
Users
International Bureau of Weights and Measures
(BIPM)
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NMLs Timing Network
Existing server
Planned
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NML GPS Common-View Time Transfer Systems
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Sample NML GPS Integrity Monitoring Daily Report
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Principle of Two-Way Satellite Time Transfer
Two-way timing pulse transmission allows direct
path length measurement.
INTELSAT 702 183 E
Timing Pulse
CRL (Tokyo)
NML (Sydney)
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Future Directions

• Support of Electronic Commerce
• In-house NML-verified time sources for clients
• Post-facto verifiable transaction time
  stamping
• Web-based time
• Expansion of telephone computer time service
• New Internet time transmission technologies
• Closer ties to the Geodetics/Geomatics
  communities
• Low-frequency time broadcast service (expensive)