– the intergovernmental organization through which Member States act together
     on matters related to measurement science and measurement standards.
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CCTF Working Group on Primary and Secondary Frequency Standards (CCTF-WGPSFS)

Terms of reference


  1. Develop and propose standards for the documentation of frequency biases and uncertainties, operational details, and frequency transfer uncertainties for Primary and Secondary Frequency Standards (PFSs and SFSs). Develop and propose standards for the reporting of the results of a PFS/SFS evaluation to the BIPM.
  2. Provide a forum to evaluate and discuss the consistency among primary frequency standards.
  3. Provide a forum to discuss and assess the overall knowledge of the accuracy of the SI second for use in establishing the frequencies of secondary standards (microwave and optical) and possibly an eventual redefinition of the second.
  4. Interact with the BIPM on issues related to PFS/SFS contributions to the accuracy of TAI, particularly in the process of integration of the first reports of a standard.
  5. Encourage and facilitate direct comparisons between primary and secondary frequency standards.
  6. Encourage and support laboratories with new standards under construction.
  7. September 2012


  • Dr Stefan Weyers  (PTB)


  • Dr Gérard Petit  (BIPM)


  • Dr Michel Abgrall (LNE-SYRTE)
  • Dr Poonam Arora (NPLI)
  • Dr Scott Beattie (NRC)
  • Mr Laurent-Guy Bernier (METAS)
  • Dr Yuri Domnin (VNIIFTRI)
  • Dr Fang Fang (NIM)
  • Dr Myoung-Sun Heo (KRISS)
  • Dr Tetsuya Ido (NICT)
  • Dr Motohiro Kumagai (NICT)
  • Dr Filippo Levi (INRIM)
  • Dr Tianchu Li (NIM)
  • Mr Jérôme Lodewyck (LNE-SYRTE)
  • Dr Andrew Ludlow (NIST)
  • Dr Jacques Morel (METAS)
  • Dr Sang Eon Park (KRISS)
  • Dr Thomas E. Parker (NIST)
  • Dr Ekkehard Peik (PTB)
  • Dr Krzysztof Szymaniec (NPL)
  • Dr Akifumi Takamizawa (NMIJ/AIST)
  • Dr Masami Yasuda (NMIJ/AIST)
  • Representatives of all NMIs operating Primary and/or Secondary Frequency Standards (PFSs, SFSs) reporting to TAI;
  • Representatives of NMIs that are planning to operate at least one PFS/SFS reporting to TAI;
  • Representatives of the BIPM

  CCTF: Upcoming meetings
11–12 March 2021: Second session of the 22nd meeting of the CCTF (online)
18–19 March 2021: Second session of the 22nd meeting of the CCTF (online)
27 June to 1 July 2022: 23rd meeting of the CCTF and related meetings

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BIPM Workshop on Advanced Time & Frequency Transfer Techniques 2011