Recommendation 2 of the 95th CIPM (2006)

Coordination of the development of advanced time and frequency transfer techniques

The International Committee for Weights and Measures (CIPM),


  • the availability of high performance cold atom microwave clocks,
  • the rapid improvement of optical frequency standards in different institutes,
  • the upcoming need to compare these remote standards at a level of estimated accuracy and stability which is not currently possible; and

considering that

  • different technical possibilities for comparison that include optical fibre links, transportable optical frequency standards, optical satellite links and improved microwave links have been identified as possibly useful for the purpose,
  • improvements in time and frequency transfer would have major applications to the performance assessment of current frequency standards and would support the progress of future primary frequency standards and clocks,
  • the associated improvement of the realization of Coordinated Universal Time (UTC) would be beneficial for foreseeable applications in many fields of science and technology,
  • a new Working Group on Coordination of the Development of Advanced Time and Frequency Transfer Techniques composed of experts from various fields, such as optical frequency metrology, time scale generation, and time and frequency transfer, to address and coordinate these issues is established;

recommends that

  • the time and frequency community actively pursue this research in a coordinated manner,
  • the International Bureau of Weights and Measures (BIPM) continue to facilitate the activities of the different working groups of the CCTF and establish the necessary interactions with other relevant bodies such as the International GNSS Service (IGS), International Union of Geodesy and Geophysics (IUGG), International Telecommunication Union (ITU), International Union of Radio Science (URSI) and other competent organizations,
  • national and international science organizations and space agencies give this development due consideration and weight, and
  • national governments and international bodies provide funding to support the development of these activities.

DOI : 10.59161/CIPM2006REC2E

The reader should note that the official version of this Resolution is the French text

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