TIME AND FREQUENCY METROLOGY WORKING GROUP Working to support time and frequency metrology throughout the Americas

Transcription

1 J. Mauricio Lopez R. a, Michael A. Lombardi b, Andrew N. Novick b, Jean-Simon Boulanger c, Raymond Pelletier c, Carlos Donado M. d, and Ricardo Carvalho e a Centro Nacional de Metrología (CENAM), Querétaro, Mexico, [email protected] b National Institute of Standards and Technology, Boulder, Colorado, United States, [email protected] c National Research Council (NRC), Ottawa, Canada, [email protected] d Centro Nacional de Metrología de Panamá (CENAMEP), Panama City, Panama e Observatorio Nacional, Rio de Janeiro, Brazil

2 Outline Motivations The TheGPS system SIM SIM time time and and frequency network SIM SIM and andbipm comparisons Conclusions and andnear nearfuture work

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4 Country BIPM/ CGPM Member? Maintains Time and Freq. Lab? Submits to BIPM? Argentina Member Yes Yes Brazil Member Yes Yes Canada Member Yes Yes Chile Member Yes Yes Colombia No Yes No Costa Rica Associate Yes No Dominican Rep. Member Unknown No Ecuador Associate Yes No El Salvador No Interested No Guatemala No Yes No Jamaica Associate Yes No Mexico Member Yes Yes Panama Associate Yes Yes Paraguay No Interested No Peru No Interested No Trinidad / Tobago No Interested No United States Member Yes Yes Uruguay Member Interested No Venezuela Member Yes No

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6 -GPS stands for Global Positioning System - -Space-based radio positioning system -Provides users with highly accurate position, velocity, and time data

7 24 satelites with atomic clocks on board semi-synchronous orbit height of 4.2 earth radii (~20,200 km) 6 orbital planes, 55 degrees inclination to equatorial plane

8 Operates on two L-band frequencies GHz and GHz At least four satellites always in view

9 GPS satellite with an atomic clock on board Slave oscillator on earth

10 Velocity of propagation is not constant along the path Ionosphere Troposphere GPS Receiver

11 15 hours

12 nanoseconds Modified Julian Day (Thousands) March 25 th,1990

13 Oscillator in common view Propagation media Oscillator 1 Oscillator 2

14 Variation on the velocity of propagation introduces a uncertainty which is usually a few nanoseconds Ionosphere Troposphere L >> 10 km L < 10 km

15 Técnica de COMMON-VIEW TIME AND FREQUENCY METROLOGY WORKING GROUP Clock B Clock A

16 Técnica de COMMON-VIEW GPS-B receiver GPS-A receiver Common agenda to view GPS satellites

17 Técnica de COMMON-VIEW t B = t B t GPS ±ε B t A = t A t GPS ±ε A t BA = t B - t A =(t B -t GPS + ε B ) (t A t GPS + ε A ) = t B -t A ± (ε B + ε A )

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19 NRC NRC NIST NIST CENAM CENAM ICE ICE CENAMEP CENAMEP SIC SIC ONRJ ONRJ INTI INTI

20 SIM GPS system - Multichannel (8) GPS receiver - SIM receiver sends data automatically to the SIM server every 10 minutes - includes SIM s own software (developed by NIST) - Includes a PC. It is able to show common view results in near real time among participating laboratories

21 SIM GPS antenna Novatel antenna Rejects multiple reflections of the GPS signal

22 SIM Network server tf.nist.gov/sim/

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24 SIM Time and Frequency comparison network: a democratic system

25 Comparison between NIST and CENAM

26 Comparison between NIST and CENAM

27 Comparison between NRC and ONRJ

28 Comparison between NRC and ONRJ

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30 SIM Network Circular-T SIM Network Circular-T Nanoseconds days Modified Julian Dates UTC(CNM) UTC(CNMP). 350 ns Nanoseconds days Modified Julian Dates UTC(NIST) UTC(CNMP). 400 ns SIM Network 40 SIM Network Circular-T Circular-T Nanoseconds ns Nanoseconds ns days Modified Julian Dates UTC(NIST) UTC(CNM). 40 SIM Network Circular-T 30 SIM BIPM days Modified Julian Dates UTC(NRC) UTC(CNMP). 60 SIM Network Circular-T Nanoseconds days Modified Julian Dates UTC(CNM) UTC(NRC). 50 ns Nanoseconds days Modified Julian Dates UTC(NIST) UTC(NRC). 60 ns

31 Summary of uncertainties (in nanoseconds) for all six comparisons (March-April 2006) CNM CNMP NIST CNM CNM NRC NIST CNMP NRC CNMP NIST NRC Baseline (km) Mean Freq. Offset Mean Time Offset U A, σ x (τ) U B, Calibration U B, Coordinates U B, Environment U B, Multipath U B, Ionosphere U B, Ref. delay U B, Resolution U C, k =

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33 Conclusions TIME AND FREQUENCY METROLOGY WORKING GROUP 1. The SIM time and frequency network began operation in June Currently 7 NMIs are in participation. 2. The network is expected to enhance time and frequency Metrology capabilities on the SIM region by providing NMIs with a convenient way to compare their standards and to establish traceability to the SI. 3. Due to the SIM T&F Network some labs are in the process of acquiring Cs clocks. 4. The SIM network produces results that agree closely with results published in the BIPM s Circular-T, but have the distinct advantage of being available in near real time. 5. New labs will be joining the network during the next weeks or months (Argentina, Guatemala and )

38 Conclusions TIME AND FREQUENCY METROLOGY WORKING GROUP 6. Measurement results produced by the SIM T&F network will be used in the near future to generate a virtual time scale called SIM-time. SIMtime will be a time scale with very high metrological characteristics (accuracy and stability) accessible in real time. CENAM is developing an algorithm to generate the SIM-time scale starting on the second part of Improvement of time and frequency capabilities can be observed at SIM as result of the SIM T&F network. However, it is necessary to continue supporting Time and Frequency activities in the SIM region not only providing more SIM type GPS receivers but also with training courses to those countries interested on improving their T&F laboratories or establishing their own one. 8. Enhanced time and frequency capabilities on SIM laboratories along with the SIM-time scale will help to pave the way to improve Metrology and provide a better support to industry in the Americas.

39 Conclusions TIME AND FREQUENCY METROLOGY WORKING GROUP 6. Measurement results produced by the SIM T&F network will be used in the near future to generate a virtual time scale called SIM-time. SIM-time will be a time scale with very high metrological characteristics (accuracy and stability) accessible in real time. CENAM is developing an algorithm to generate the SIMtime scale starting on the second part of Improvement of time and frequency capabilities can be observed at SIM as result of the SIM T&F network. However, it is necessary to continue supporting Time and Frequency activities in the SIM region not only providing more SIM type GPS receivers but also with training courses to those countries interested on improving their T&F laboratories or establishing their own one. 8. Enhanced time and frequency capabilities on SIM laboratories along with the SIM-time scale will help to pave the way to improve Metrology and provide a better support to industry in the Americas.

40 Conclusions TIME AND FREQUENCY METROLOGY WORKING GROUP 6. Measurement results produced by the SIM T&F network will be used in the near future to generate a virtual time scale called SIM-time. SIM-time will be a time scale with very high metrological characteristics (accuracy and stability) accessible in real time. CENAM is developing an algorithm to generate the SIMtime scale starting on the second part of Improvement of time and frequency capabilities can be observed at SIM as result of the SIM T&F network. However, it is necessary to continue supporting Time and Frequency activities in the SIM region not only providing more SIM type GPS receivers but also with training courses to those countries interested on improving their T&F laboratories or establishing their own one. 8. Enhanced time and frequency capabilities on SIM laboratories along with the SIM-time scale will help to pave the way to improve Metrology and provide a better support to industry in the Americas.

41 Thank Thank you you for for your your attention attention J. Mauricio Lopez R. a, Michael A. Lombardi b, Andrew N. Novick b, Jean-Simon Boulanger c, Raymond Pelletier c, Carlos Donado M. d, and Ricardo Carvalho e a Centro Nacional de Metrología (CENAM), Querétaro, Mexico, [email protected] b National Institute of Standards and Technology, Boulder, Colorado, United States, [email protected] c National Research Council (NRC), Ottawa, Canada, [email protected] d Centro Nacional de Metrología de Panamá (CENAMEP), Panama City, Panama e Observatorio Nacional, Rio de Janeiro, Brazil