Sistema Sim Tiempo

J. Mauricio Lopez R.a, Michael A. Lombardib, Andrew N. Novickb, Jean-Simon Boulangerc,Raymond Pelletierc, Carlos Donado M.d, and Ricardo Carvalho e

a Centro Nacional de Metrología (CENAM), Querétaro, Mexico, [email protected] National Institute of Standards and Technology, Boulder, Colorado, United States, [email protected]

c National Research Council (NRC), Ottawa, Canada, [email protected] Centro Nacional de Metrología de Panamá (CENAMEP), Panama City, Panama

e Observatorio Nacional, Rio de Janeiro, Brazil

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

1. Motivations1. Motivations

2. The GPS system2. The GPS system

3. SIM time and frequency network3. SIM time and frequency network

4. SIM and BIPM comparisons4. SIM and BIPM comparisons

5. Conclusions and near future work5. Conclusions and near future work

OutlineOutline



NoYesNoGuatemala

NoYesMemberVenezuela

NoInterestedMemberUruguay

YesYesMemberUnited States

NoInterestedNoTrinidad / Tobago

NoInterestedNoPeru

NoInterestedNoParaguay

YesYesAssociatePanama

YesYesMemberMexico

NoYesAssociateJamaica

NoInterestedNoEl Salvador

NoYesAssociateEcuador

NoUnknownMemberDominican Rep.

NoYesAssociateCosta Rica

NoYesNoColombia

YesYesMemberChile

YesYesMemberCanada

YesYesMemberBrazil

YesYesMemberArgentina

Submits to BIPM?

Maintains Time and Freq. Lab?

BIPM/CGPMMember?

Country

-GPS stands for Global Positioning System--Space-based radio positioning system

-Provides users with highly accurate position, velocity, and time data


24 satelites with atomicclocks on board

semi-synchronous orbit height of 4.2 earth radii (~20,200 km)

6 orbital planes, 55 degrees inclination to equatorial plane


Operates on two L-band frequencies 1.57542 GHz and 1.2276 GHz

At least four satellites always in view


GPS satellite with an

“Slave” oscillator on earth

atomic clock on board


Velocity of propagation is not constant along the path

Troposphere

Ionosphere

GPS Receiver


15 hours


300

200

100

0

-100

-200

-300

-400

-500

-6007954.007 7963.504 7979.935 7989.824 7998.822 8009.182

nano

seco

nds

Modified Julian Day - 40000 (Thousands)

March 25th,1990



Oscillator in common view

Propagation media

Oscillator 1 Oscillator 2

Variation on the velocity of propagation introduces a uncertainty which is usually a few nanoseconds

L >> 10 km

L < 10 km

Troposphere

Ionosphere


Técnica de COMMON-VIEW

Clock A

Clock B


TIME AND FREQUENCY METROLOGY WORKING GROUPWorking to support time and frequency metrology throughout the AmericasTécnica de COMMON-VIEW

GPS-A receiver

GPS-B receiver

Common agenda to “view” GPS satellites

TIME AND FREQUENCY METROLOGY WORKING GROUPWorking to support time and frequency metrology throughout the AmericasTécnica de COMMON-VIEW

∆tA= tA – tGPS ± εA

∆tB= tB – tGPS ± εB

∆tBA = ∆tB - ∆tA =(tB-tGPS + εB) – (tA – tGPS + εA) = tB - tA ± (εB + εA)

NRCNRC

NISTNIST

CENAMCENAM

CENAMEPCENAMEP

ONRJONRJ

ICEICE

SICSIC


INTIINTI

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


SIM GPS antenna


Novatel antenna

Rejects multiple reflections of theGPS signal

SIM Network server

tf.nist.gov/sim/



SIM Time and Frequency comparison network: a democratic system

Comparison between NIST and CENAM


Comparison between NRC and ONRJ


-4900

-4850

-4800

-4750

-4700

-4650

-4600

-4550

-4500

-4450

53790 53800 53810 53820 53830 53840 53850 53860

Modified Julian Dates

Nan

osec

onds

SIM NetworkCircular-T

-30

-20

-10

0

10

20

30

40

53790 53800 53810 53820 53830 53840 53850 53860


Nan

osec

onds


-30

-20

-10

0

10

20

30

40

53790 53800 53810 53820 53830 53840 53850 53860


Nan

osec

onds


-4950

-4900

-4850

-4800

-4750

-4700

-4650

-4600

-4550

-4500

-4450

53790 53800 53810 53820 53830 53840 53850 53860Modified Julian Dates

Nan

osec

onds


-4950

-4900

-4850

-4800

-4750

-4700

-4650

-4600

-4550

-4500

53790 53800 53810 53820 53830 53840 53850 53860


Nan

osec

onds


-20

-10

0

10

20

30

40

50

60

53790 53800 53810 53820 53830 53840 53850 53860


Nan

osec

onds


UTC(NIST) − UTC(CNMP).UTC(CNM) − UTC(CNMP).

UTC(NIST) − UTC(CNM).

UTC(CNM) − UTC(NRC).

UTC(NRC) − UTC(CNMP).

UTC(NIST) − UTC(NRC).

60 days

350

ns

60 days

60 days

60 days

60 days

60 days

50 n

s50

ns

400

ns35

0 ns

60 n

s

BIPMBIPMSIMSIM

Summary of uncertainties (in nanoseconds) for all six comparisons (March-April 2006)

12.914.014.013.513.113.5UC, k = 2

0.050.050.050.050.050.05UB, Resolution

0.50.50.50.50.50.5UB, Ref. delay

1.5332.51.52UB, Ionosphere

222222UB, Multipath

333333UB, Environment

333333UB, Coordinates

444444UB, Calibration

11.51.51.41.21.8UA, σx(τ)

+21.2−4702.8−4680.7+11.0+10.3−4690.4Mean Time Offset

−7.7 × 10-15−6.3 × 10-14−7.0 × 10-14−4.8 × 10-15−2.8 × 10-15−6.7 × 10-14Mean Freq. Offset

2471.33989.04194.93520.72198.92544.0Baseline (km)

NIST − NRCNRC − CNMPNIST − CNMPCNM − NRCNIST − CNMCNM − CNMP


Conclusions

2. The network is expected to enhance time and frequency Metrology capabilitieson 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 Csclocks.

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 …)

1. The SIM time and frequency network began operation in June 2005. Currently 7 NMIs are in participation.


Conclusions

3. Due to the SIM T&F Network some labs are in the process of acquiring Cs clocks.





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.

Conclusions

3. Due to the SIM T&F Network some labs are in the process of acquiring Cs clocks.






Conclusions


4. The SIM network produces results that agree closely with resultspublished in the BIPM’s Circular-T, but have the distinct advantage of being available in near real time.





Conclusions







Conclusions

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 SIM-time scale starting on the second part of 2008.


7. 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.

Conclusions



7. 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.

Conclusions



7. 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.


J. Mauricio Lopez R.a, Michael A. Lombardib, Andrew N. Novickb, Jean-Simon Boulangerc,Raymond Pelletierc, Carlos Donado M.d, and Ricardo Carvalho e

a Centro Nacional de Metrología (CENAM), Querétaro, Mexico, [email protected] National Institute of Standards and Technology, Boulder, Colorado, United States, [email protected]

c National Research Council (NRC), Ottawa, Canada, [email protected] Centro Nacional de Metrología de Panamá (CENAMEP), Panama City, Panama

e Observatorio Nacional, Rio de Janeiro, Brazil

Thank you for your attention

Thank you for your attention

Sistema Sim Tiempo

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