Progress in the generation of the UTC(CNM) in terms of a virtual clock

The Time and Frequency Division of the Centro Nacional de Metrologia (CENAM) has developed and implemented a time scale algorithm in order to give better characteristics of stability, accuracy and robustness to the UTC(CNM). The UTC(CNM) has been generated since March 1996 with no interruptions and since MJD 53 000 the |UTC - UTC(CNM)| time differences were smaller than 50 ns during more than 90% of the time. When time differences were bigger than 50 ns they were smaller than 80 ns; time stability of the UTC(CNM) was 4.3 ns for 5 days and 30 ns for 1 year. With the new method to generate the UTC(CNM), time differences |UTC - UTC(CNM)| no bigger than 25 ns, a time stability of 2 ns for 5 days and 15 ns for 1 year are expected. In this paper we report on the progress made at the CENAM Time and Frequency Division to generate the UTC(CNM) in terms of a virtual clock. We present and discuss preliminary results when the time scale algorithm is implemented on four industrial Cs clocks (two of them high performance clocks) and one active hydrogen maser. (authors)