Recommendation 1 of the 17th CCTF (2006)

Recommended values of standard frequencies for applications including the practical realization of the metre and secondary representations of the second

The Consultative Committee for for Time and Frequency (CCTF),

considering

• the proposal expressed by the 12th Consultative Committee for Length (CCL) meeting in its Recommendation CCL 2 (2005),
• the realization of direct and accurate frequency measurements made possible by the femtosecond laser comb,
• the steady reduction in uncertainties associated with frequency standards,
• the differing accuracy requirements of the CCL length metrology community and the CCTF criteria for secondary representations;

recommends that

• the CCL Mise en Pratique Working Group and CCL/CCTF Joint Working Group be combined into a single CCL-CCTF frequency standards working group,
• the Mise en Pratique-CCL list of recommended radiations and CCTF secondary representation list be combined into a single new list of “Recommended values of standard frequencies for applications including the practical realization of the metre and secondary representations of the second”,
• other frequencies may be proposed, evaluated and maintained on the frequency standards list by the CCL-CCTF Frequency Standards Working Group, not all of which are adopted as CCL-preferred radiations or CCTF-accepted representations,
• the CCTF consider and recommends those frequencies which it proposes the CIPM to accept as secondary representations of the second,
• the CCL consider and recommend those frequencies which it deems important for use in high accuracy length metrology, and
• the frequency values list is maintained on the BIPM website.

DOI : 10.59161/CCTF2006REC1E