1. J. Mauricio Lopez R. 1, Michael A. Lombardi 2, N. Diaz-Mu ñ oz 1 and Eduardo de Carlos Lopez 1 1 Centro Nacional de Metrología (CENAM), Querétaro, Mexico 2 National Institute of Standards and Technology (NIST), Boulder, Colorado, United States, A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE

2. OUTLINE 1. Motivations 2. The SIM Time Network (SIMTN) 3. The SIM time scale (SIMT) 4. New weights algorithm 5. Conclusions and future work A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE J. Mauricio Lopez R., Michael A. Lombardi, N. Diaz-Mu ñ oz and Eduardo de Carlos Lopez

3. OUTLINE 1. Motivations 2. The SIM Time Network (SIMTN) 3. The SIM time scale (SIMT) 4. New weights algorithm 5. Conclusions and future work A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE J. Mauricio Lopez R., Michael A. Lombardi, N. Diaz-Mu ñ oz and Eduardo de Carlos Lopez

4. A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE

5. TIME The most measured physical quantity TWO FACES OF TIME The current SI Time is the most accurate measurement Scientific and fundamental research Technological and practical applications

6. OUTLINE 1. Motivations 2. The SIM Time Network (SIMTN) 3. The SIM time scale (SIMT) 4. New weights algorithm 5. Conclusions and future work A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE J. Mauricio Lopez R., Michael A. Lombardi, N. Diaz-Mu ñ oz and Eduardo de Carlos Lopez

7. TIME AND FREQUENCY METROLOGY WORKING GROUP Working to support time and frequency metrology throughout the Americas 34 NMIs 3 NMIs 7 NMIs 5 NMIs 14 NMIs

8. TIME AND FREQUENCY METROLOGY WORKING GROUP Working to support time and frequency metrology throughout the Americas Current SIMTN members 18  1

9. TIME AND FREQUENCY METROLOGY WORKING GROUP Working to support time and frequency metrology throughout the Americas SIMTN Area Coverage 18  1 SIM NMIs

10. Clock A Clock B A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE

11. Clock A Clock B GPS satellite Measuring system A Measuring system B A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE

12. Clock A Clock B GPS satellite Measuring system A Measuring system B Time of the day GPS –Clock A Time of the day GPS – clock B A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE

13. Clock A Clock B Measuring system A Measuring system B SIMTN servers CENAM NIST NRC ONRJ Time of the day GPS –Clock A Time of the day GPS – clock B A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE

14. time Clock A – Clock B ± u (Clock A – S) – (Clock B – S) = (Clock A – Clock B) + (d SA – d SB ) Time of the day GPS – clock B Time of the day GPS –Clock A A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE

15. N C number of bilateral comparisons N number of laboratories in the network For N=18 there are N C = 153 bilateral comparisons links in the SIMTN A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE

16. N C number of bilateral comparisons N number of laboratories in the network For N=18 there are N C = 153 bilateral comparisons links in the SIMTN A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE

17. Shortest link 215.301 km baseline Argentina to Uruguay A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE links in the SIMTN Longest link 8676.511 km baseline USA to Argentina

18. http://www.tf.nist.gov/sim

19. CENAM Time – NIST time A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE

20. OUTLINE 1. Motivations 2. The SIM Time Network (SIMTN) 3. The SIM time scale (SIMT) 4. New weights algorithm 5. Conclusions and future work A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE J. Mauricio Lopez R., Michael A. Lombardi, N. Diaz-Mu ñ oz and Eduardo de Carlos Lopez

21.  30 Cesium beam clocks 9 Active Hydrogen Masers 1 Cs fountain clock (NIST) 2 Cs fountain clocks in progress (NRC and CENAM) 4 ensemble time scales (NRC, NIST, CENAM and ONRJ) A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE

22. A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE

23. SIMT(k) (clock or time scale) SIMTN Computer 8-channel GPS Receiver New data every 10 minutes Time Interval Counter FTP Server (CENAM) (processes CVGPS and AVGPS data) 1 pps GPS satellites 1.57542 GHz (L1 carrier) 1 pps FTP FTP Server (NIST) (processes CVGPS and AVGPS data) FTP Server (NRC) (processes CVGPS and AVGPS data) k-th member of SIMTN (18 members) SIMTN Web Server (NIST) (publishes comparisons every 10 minutes) (publishes SIMT every hour) SIMTN Web Server (CENAM) (publishes comparisons every 10 minutes) SIMTN Web Server (NRC) (publishes comparisons every 10 minutes) FTP SIMT Computer (CENAM) (reads SIMTN data feeds, runs SIMT algorithms, generates SIMT every hour) SIMTN data feeds (HTTP) FTP (new data every hour) 10 MHz GPS antenna A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE

24. Prediction of the time difference between clock k and SIMT at the future time t+  Time difference between clock k and SIMT at the time t (0th order aproximation) Correction due to sistematic frequency difference between clock k and SIMT (1st order aproximation) Correction due to non constant (linear) frequency difference between clock k and SIMT (2th order aproximation) Taylor series expansion on the predicted time difference of clock k respect to SIMT A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE

25. Time difference between clock k and SIMT at the current time t+  Prediction of the time difference between clock j and SIMT made at the past time t Time difference between clock j and clock k at the time t+  Averaging A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE

26. A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE

27. OUTLINE 1. Motivations 2. The SIM Time Network (SIMTN) 3. The SIM time scale (SIMT) 4. New weights algorithm 5. Conclusions and future work A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE J. Mauricio Lopez R., Michael A. Lombardi, N. Diaz-Mu ñ oz and Eduardo de Carlos Lopez

28. Since February, 2012 A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE

29. A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE

30. February 9, 2012 A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE

31. A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE

32. A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE

33. A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE

34. A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE

35. A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE

36. A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE

37. A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE

38. OUTLINE 1. Motivations 2. The SIM Time Network (SIMTN) 3. The SIM time scale (SIMT) 4. New weights algorithm 5. Conclusions and future work A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE J. Mauricio Lopez R., Michael A. Lombardi, N. Diaz-Mu ñ oz and Eduardo de Carlos Lopez

39. 3 +1 SIMTN servers CENAM NIST NRC ONRJ A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE

40. Computation of SIMT in 3 different locations CENAM NIST NRC A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE

41. Cs clock(s) will be included SIMT(k) will be steered to SIMT A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE

42. Bolivia 18 SIM NMIs + A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE

43. More room to improve the SIMT stability A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE

44. Development of new SIM GPS systems with full compatibility with the BIPM algorithm to produce the UTC (in progress). More SIM NMIs contributing data to TAI. A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE

45. J. Mauricio Lopez R. 1, Michael A. Lombardi 2, N. Diaz-Mu ñ oz 1 and Eduardo de Carlos Lopez 1, 1 Centro Nacional de Metrología (CENAM), Querétaro, Mexico 2 National Institute of Standards and Technology (NIST), Boulder, Colorado, United States, THANK YOU FOR YOUR ATTENTION! A NEW ALGORITHM FOR CLOCK WEIGHTS FOR THE SIM TIME SCALE J. Mauricio Lopez R., Michael A. Lombardi, N. Diaz-Mu ñ oz and Eduardo de Carlos Lopez