Table 6. Measurements of the duration of the TAI scale interval TAI is a realization of coordinate time TT. The following tables give the fractional deviation d of the scale interval of TAI from that of TT (in practice the SI second on the geoid), i.e. the fractional frequency deviation of TAI with the opposite sign: d = -yTAI. In Table 6A, d is obtained on the given periods of estimation by comparison of the TAI frequency with that of the individual primary frequency standards (PFS) IT-CsF2, NIM5, NIST-F2, NPL-CSF2, NPLI-CsF1, PTB-CS1, PTB-CS2, PTB-CSF1, PTB-CSF2, SU-CsFO2, SYRTE-FO1 and SYRTE-FO2 reported on the year 2014. In Table 6B, d is obtained on the given periods of estimation by comparison of the TAI frequency with that of the individual secondary frequency standard (SFS) SYRTE-FORb reported on the year 2014. Previous calibrations are available in the successive annual reports of the BIPM Time Section volumes 1 to 18 and in the BIPM Annual Report on Time Activities volumes 1 to 8. Each comparison is provided with the following information: uA is the uncertainty originating in the instability of the PFS, uB is the combined uncertainty from systematic effects, ulink/lab is the uncertainty in the link between the PFS and the clock participating to TAI, including the uncertainty due to dead-time, ulink/TAI is the uncertainty in the link to TAI, computed using the standard uncertainty of [UTC-UTC(k)], u is the quadratic sum of all four uncertainty values. In addition, Table 6B includes the following information: uSRep is the recommended uncertainty of the secondary representation of the second, as specified in the CIPM Recommendation identified under Ref(uS). In these tables, a frequency over a time interval is defined as the ratio of the end-point phase difference to the duration of the interval. The typical characteristics of the calibrations of the TAI frequency provided by the different primary and secondary standards reported in 2014 are indicated below. Reports of individual evaluations may be found at ftp://62.161.69.5/pub/tai/data/PFS_reports. Ref(uB) is a reference giving information on the value of uB as stated in the 2014 reports, uB(Ref) is the uB value stated in this reference. Note that the current uB values are generally not the same as the peer reviewed values given in Ref(uB). Primary Standard Type Type B std. uB(Ref)/10**-15 Ref(uB) Comparison Number/typical /selection uncertainty/ 10**-15 with duration of comp. IT-CsF2 Fountain (0.17 to 0.25) 0.18 [1] H maser 15 / 10 d to 30 d NIM5 Fountain 1.4 1.4 [2] H maser 6 / 15 d to 30 d NIST-F2 Fountain 0.15 0.11 [3] H maser 3 / 25 d to 45 d NPL-CSF2 Fountain (0.20 to 0.27) 0.23 [4] H maser 8 / 10 d to 30 d NPLI-CsF1 Fountain (2.36 to 3.01) 2.5 [5] H maser 7 / 10 d to 20 d PTB-CS1 Beam /Mag. 8 8. [6] TAI 12 / 30 d PTB-CS2 Beam /Mag. 12 12. [7] TAI 12 / 30 d PTB-CSF1 Fountain (0.70 to 0.73) 1.4 [8] H maser 6 / 10 d to 35 d PTB-CSF2 Fountain (0.28 to 0.35) 0.41 [9] H maser 9 / 10 d to 35 d SU-CsFO2 Fountain 0.50 then 0.25 0.50 [10] H maser 9 / 20 d to 30 d SYRTE-FO1 Fountain (0.36 to 0.41) 0.37 [11] H maser 10 / 15 d to 35 d SYRTE-FO2 Fountain (0.25 to 0.29) 0.23 [11] H maser 11 / 20 d to 35 d Secondary Standard Type Type B std. uB(Ref)/10**-15 Ref(uB) Comparison Number/typical uncertainty/ 10**-15 with duration of comp. SYRTE-FORb Fountain (0.29 to 0.36) 0.32 [12] H maser 10 / 10 d to 30 d More detailed information on the characteristics and operation of individual PFS and SFS may be found in the annexes supplied by the individual laboratories. Table 6A. Measurements of the duration of the TAI scale interval by Primary Frequency Standards Standard Period of d/10**-15 uA/10**-15 uB/10**-15 ulink/lab ulink/TAI u/10**-15 Note estimation /10**-15 /10**-15 IT-CsF2 56079 56099 2.38 0.32 0.25 0.20 0.28 0.53 IT-CsF2 56194 56214 -0.11 0.42 0.21 0.20 0.28 0.58 IT-CsF2 56234 56249 -0.93 0.31 0.18 0.10 0.37 0.52 IT-CsF2 56394 56424 -0.20 0.34 0.18 0.20 0.20 0.48 IT-CsF2 56614 56634 -1.31 0.33 0.18 0.20 0.28 0.51 IT-CsF2 56634 56649 -0.74 0.41 0.18 0.20 0.37 0.61 IT-CsF2 56724 56749 -1.08 0.33 0.19 0.14 0.23 0.47 IT-CsF2 56749 56774 -0.98 0.35 0.19 0.14 0.23 0.48 IT-CsF2 56779 56799 -0.78 0.33 0.19 0.10 0.28 0.48 IT-CsF2 56814 56829 -1.50 0.31 0.18 0.17 0.37 0.54 IT-CsF2 56839 56864 -1.14 0.28 0.18 0.18 0.23 0.44 IT-CsF2 56939 56949 0.89 1.30 0.17 0.36 0.53 1.46 IT-CsF2 56954 56964 0.78 1.30 0.17 0.32 0.62 1.49 IT-CsF2 56964 56979 -0.24 1.00 0.17 0.22 0.49 1.15 IT-CsF2 56994 57014 0.33 0.70 0.18 0.14 0.28 0.79 NIM5 56669 56684 -1.25 0.60 1.40 0.20 0.85 1.76 NIM5 56699 56714 -1.66 0.50 1.40 0.20 0.85 1.73 NIM5 56729 56749 -0.64 0.80 1.40 0.10 0.66 1.74 NIM5 56759 56779 0.43 0.80 1.40 0.10 0.66 1.74 NIM5 56779 56809 0.21 0.60 1.40 0.20 0.35 1.58 NIM5 56809 56824 1.53 0.90 1.40 0.20 0.37 1.72 NIST-F2 56489 56534 -1.22 0.44 0.15 0.16 0.14 0.51 NIST-F2 56804 56829 -1.85 0.53 0.15 0.23 0.23 0.64 NIST-F2 56894 56929 -0.86 0.42 0.15 0.18 0.17 0.51 NPL-CsF2 56654 56684 0.55 0.22 0.23 0.08 0.20 0.38 NPL-CsF2 56684 56714 -0.33 0.21 0.21 0.03 0.20 0.36 NPL-CsF2 56714 56744 -0.09 0.22 0.22 0.09 0.20 0.38 NPL-CsF2 56744 56774 0.35 0.21 0.20 0.06 0.20 0.36 NPL-CsF2 56774 56804 -1.34 0.24 0.20 0.13 0.20 0.39 NPL-CsF2 56899 56929 0.57 0.36 0.27 0.14 0.20 0.51 NPL-CsF2 56929 56949 0.70 0.37 0.21 0.05 0.28 0.51 NPL-CsF2 56954 56964 0.61 0.91 0.24 0.42 0.62 1.20 NPLI-CsF1 56419 56439 -0.27 0.53 2.60 0.13 0.28 2.67 NPLI-CsF1 56514 56529 3.54 0.47 3.01 0.15 0.37 3.07 NPLI-CsF1 56589 56599 0.97 0.90 2.65 0.20 0.53 2.85 NPLI-CsF1 56604 56614 1.35 0.61 2.71 0.19 0.53 2.83 NPLI-CsF1 56644 56654 -0.85 0.74 2.74 0.18 0.53 2.89 NPLI-CsF1 56659 56669 1.02 0.75 2.36 0.18 0.53 2.54 NPLI-CsF1 56679 56689 -0.27 0.93 2.36 0.19 0.53 2.60 PTB-CS1 56654 56684 -7.69 6.00 8.00 0.00 0.07 10.00 (1) PTB-CS1 56684 56714 -11.51 6.00 8.00 0.00 0.07 10.00 PTB-CS1 56714 56744 -9.24 6.00 8.00 0.00 0.07 10.00 PTB-CS1 56744 56774 -6.50 6.00 8.00 0.00 0.07 10.00 PTB-CS1 56774 56804 -4.41 6.00 8.00 0.00 0.07 10.00 PTB-CS1 56804 56834 -8.20 6.00 8.00 0.00 0.07 10.00 PTB-CS1 56834 56869 -8.97 6.00 8.00 0.00 0.06 10.00 PTB-CS1 56869 56899 -12.55 6.00 8.00 0.00 0.07 10.00 PTB-CS1 56899 56929 -10.16 6.00 8.00 0.00 0.07 10.00 PTB-CS1 56929 56959 -11.24 6.00 8.00 0.00 0.07 10.00 PTB-CS1 56959 56989 -12.28 6.00 8.00 0.00 0.10 10.00 PTB-CS1 56989 57019 -8.12 6.00 8.00 0.00 0.13 10.00 Table 6A. (Cont.) Standard Period of d/10**-15 uA/10**-15 uB/10**-15 ulink/lab ulink/TAI u/10**-15 estimation /10**-15 /10**-15 PTB-CS2 56654 56684 0.02 3.00 12.00 0.00 0.07 12.37 (1) PTB-CS2 56684 56714 3.38 3.00 12.00 0.00 0.07 12.37 PTB-CS2 56714 56744 -0.83 3.00 12.00 0.00 0.07 12.37 PTB-CS2 56744 56774 -1.37 3.00 12.00 0.00 0.07 12.37 PTB-CS2 56774 56804 -7.08 3.00 12.00 0.00 0.07 12.37 PTB-CS2 56804 56834 -7.85 3.00 12.00 0.00 0.07 12.37 PTB-CS2 56834 56869 -5.27 3.00 12.00 0.00 0.06 12.37 PTB-CS2 56869 56899 -5.07 3.00 12.00 0.00 0.07 12.37 PTB-CS2 56899 56929 -3.41 3.00 12.00 0.00 0.07 12.37 PTB-CS2 56929 56959 -3.10 3.00 12.00 0.00 0.07 12.37 PTB-CS2 56959 56989 -5.07 3.00 12.00 0.00 0.10 12.37 PTB-CS2 56989 57019 -2.02 3.00 12.00 0.00 0.13 12.37 PTB-CSF1 56729 56739 -0.12 0.13 0.73 0.02 0.18 0.76 PTB-CSF1 56794 56809 -1.00 0.14 0.73 0.02 0.12 0.75 PTB-CSF1 56814 56834 -0.88 0.12 0.71 0.02 0.09 0.73 PTB-CSF1 56834 56869 -0.27 0.09 0.71 0.02 0.06 0.72 PTB-CSF1 56869 56884 0.70 0.13 0.70 0.02 0.12 0.72 PTB-CSF1 56889 56899 0.50 0.16 0.70 0.02 0.18 0.74 PTB-CSF2 56649 56679 0.45 0.13 0.33 0.01 0.07 0.36 PTB-CSF2 56689 56709 0.54 0.15 0.31 0.01 0.09 0.36 PTB-CSF2 56729 56739 0.02 0.16 0.35 0.02 0.18 0.42 PTB-CSF2 56739 56754 -0.25 0.17 0.33 0.02 0.12 0.39 PTB-CSF2 56859 56879 0.52 0.16 0.30 0.02 0.09 0.35 PTB-CSF2 56879 56899 0.69 0.17 0.28 0.02 0.09 0.34 PTB-CSF2 56904 56924 0.59 0.16 0.29 0.03 0.09 0.35 PTB-CSF2 56929 56949 0.36 0.16 0.32 0.02 0.09 0.37 PTB-CSF2 56999 57019 0.94 0.17 0.31 0.04 0.19 0.40 SU-CsFO2 56379 56409 -0.06 0.36 0.50 0.11 0.65 0.90 SU-CsFO2 56409 56439 0.49 0.28 0.50 0.10 0.65 0.87 SU-CsFO2 56439 56469 0.79 0.26 0.50 0.10 0.65 0.87 SU-CsFO2 56484 56504 0.41 0.33 0.50 0.11 0.94 1.12 SU-CsFO2 56504 56534 -0.73 0.30 0.50 0.11 0.65 0.88 SU-CsFO2 56684 56714 -0.50 0.29 0.50 0.10 0.33 0.67 SU-CsFO2 56899 56929 0.85 0.24 0.25 0.10 0.33 0.49 SU-CsFO2 56929 56959 0.13 0.22 0.25 0.11 0.33 0.48 SU-CsFO2 56959 56989 0.53 0.23 0.25 0.11 0.33 0.48 SYRTE-FO1 56694 56714 -0.49 0.42 0.41 0.10 0.28 0.66 SYRTE-FO1 56714 56744 -0.84 0.25 0.40 0.11 0.20 0.52 SYRTE-FO1 56744 56774 -1.00 0.20 0.36 0.11 0.20 0.47 SYRTE-FO1 56774 56804 -0.74 0.20 0.39 0.11 0.20 0.49 SYRTE-FO1 56804 56834 -0.90 0.30 0.37 0.10 0.20 0.52 SYRTE-FO1 56834 56869 -0.45 0.25 0.39 0.10 0.17 0.50 SYRTE-FO1 56869 56899 -0.02 0.20 0.38 0.10 0.20 0.48 SYRTE-FO1 56899 56924 -0.39 0.30 0.38 0.11 0.23 0.55 SYRTE-FO1 56944 56959 -0.03 0.32 0.39 0.10 0.37 0.63 SYRTE-FO1 56999 57019 0.67 0.20 0.37 0.10 0.28 0.52 SYRTE-FO2 56689 56714 -0.88 0.20 0.29 0.10 0.23 0.43 SYRTE-FO2 56719 56744 -1.63 0.20 0.27 0.11 0.23 0.42 SYRTE-FO2 56744 56774 -0.97 0.26 0.25 0.11 0.20 0.42 SYRTE-FO2 56774 56794 -0.56 0.20 0.26 0.13 0.28 0.45 SYRTE-FO2 56804 56834 -0.57 0.30 0.27 0.10 0.20 0.46 Table 6A. (Cont.) Standard Period of d/10**-15 uA/10**-15 uB/10**-15 ulink/lab ulink/TAI u/10**-15 estimation /10**-15 /10**-15 SYRTE-FO2 56834 56869 0.23 0.25 0.28 0.10 0.17 0.42 SYRTE-FO2 56869 56899 0.49 0.20 0.27 0.10 0.20 0.40 SYRTE-FO2 56899 56929 -0.04 0.20 0.27 0.10 0.20 0.40 SYRTE-FO2 56929 56959 0.57 0.20 0.27 0.10 0.20 0.40 SYRTE-FO2 56959 56989 1.04 0.20 0.27 0.10 0.23 0.42 SYRTE-FO2 56989 57019 0.27 0.25 0.27 0.10 0.20 0.43 Note: (1) Continuously operating as a clock participating in TAI. Table 6B. Measurements of the duration of the TAI scale interval by Secondary Frequency Standards Standard Period of d/10**-15 uA/10**-15 uB/10**-15 ulink/lab ulink/TAI u/10**-15 uSRep Ref(uS) estimation /10**-15 /10**-15 SYRTE-FORb 56689 56704 -0.57 0.20 0.29 0.10 0.37 0.52 1.30 [13] SYRTE-FORb 56789 56804 0.18 0.60 0.36 0.12 0.37 0.80 1.30 [13] SYRTE-FORb 56804 56829 -0.17 0.40 0.32 0.11 0.23 0.57 1.30 [13] SYRTE-FORb 56854 56869 0.68 0.40 0.29 0.11 0.37 0.62 1.30 [13] SYRTE-FORb 56869 56899 0.47 0.33 0.32 0.10 0.20 0.51 1.30 [13] SYRTE-FORb 56899 56929 0.15 0.20 0.30 0.10 0.20 0.42 1.30 [13] SYRTE-FORb 56929 56959 0.67 0.20 0.29 0.10 0.20 0.42 1.30 [13] SYRTE-FORb 56959 56974 1.17 0.20 0.29 0.11 0.43 0.57 1.30 [13] SYRTE-FORb 56979 56989 0.97 0.30 0.29 0.11 0.70 0.82 1.30 [13] SYRTE-FORb 56989 57019 0.25 0.20 0.30 0.10 0.20 0.42 1.30 [13] References: [ 1] Levi F. et al., Metrologia 51, 270, 2014. [ 2] Fang F. et al., Metrologia 52, 454, 2015. 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