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

Terms of reference

The objectives of the CCL-CCTF WGFS are:

  • To make recommendations to the CCL for radiations to be used for the realization of the definition of the metre and to make recommendations to the CCTF for radiations to be used as secondary representations of the second;
  • To maintain, together with the BIPM, the list of recommended frequency standard values and wavelength values for applications including the practical realization of the definition of the metre and secondary representations of the second;
  • To take responsibility for key comparisons of standard frequencies such as CCL-K11;
  • To respond to future needs of both the CCL and CCTF concerning standard frequencies relevant to the respective communities.

May 2015

Joint Chairs:

  • Prof. Patrick Gill (NPL)
  • Prof. Fritz Riehle (PTB)



  • INRIM (Istituto Nazionale di Ricerca Metrologica)
  • NIST (National Institute of Standards and Technology, United States Department of Commerce)
  • NMIJ/AIST (National Metrology Institute of Japan, AIST)
  • NPL (National Physical Laboratory)
  • NRC (National Research Council of Canada)
  • PTB (Physikalisch-Technische Bundesanstalt)
  • SYRTE (Observatoire de Paris/Systèmes de Référence Temps-Espace)
  • VNIIFTRI (All-Russian Scientific Research Institute of Physical Technical Measurements, Rosstandart)

  CCL: Upcoming meetings
14 September 2015: Meeting of the CCL-CCTF WGFS
11–15 June 2018: 17th meeting of the CCL and related meetings

  CCTF: Upcoming meetings
6–9 June 2017: 21st meeting of the CCTF and related meetings

CCTF summary
General information
CCTF members
Strategy documents
CCTF working groups
CCTF publications and bibliography
Photographs of the CCTF
Open documents
CCTF documents
WG-ALGO documents
WGATFT documents
WGFS documents
WGGNSS documents
WGMRA documents
WGPSFS documents
WGTAI documents
WGTWSTFT documents
BIPM Workshop on Advanced Time & Frequency Transfer Techniques