UTC(INPL) - A VIRTUAL TIME-SCALE

The goal of good performance of a time scale from a small set of atomi c clocks has been realized. This time scale is both synchronized to UT C within the internationally agreed goal of a few hundred nanoseconds and syntonized to the SI second to less than 1 x 10(-13) This has been accomplished using an algorithm to combine the readings of the clocks in an adaptive way based upon their actual performance and by a smoot h automatic steering operation to maintain synchronism with UTC. This time scale, UTC(INPL), is a virtual time scale, or software clock, and is expected to have the advantage over a single primary clock of bein g more robust, more reliable and more stable than any of its physical member clocks, and insensitive to environmental perturbations, Interna tional measurements and comparisons by the GPS common-view approach ha ve validated the performance. The frequency stability sigma(y)(tau) is less than 4 x 10(-14). The software is PC-based and fully automatic. The concepts used in the generation of a virtual time scale are applic able to other areas of metrology and if incorporated could yield signi ficant improvement in other international standards.