The role of the ITU-R in time scale definition

Abstract

The International Telecommunications Union (ITU) is the leading United Nations agency for Radio and Telecommunications coordination worldwide. Overall frequency spectrum utilization is managed through Worldwide Radio Conferences, associated radiocommunication conferences and the Radiocommunication Study Groups. These Study Groups and Working Parties are devoted to specialized technical areas providing Member Nations the forum to participate, study and recommend standards to ensure equitable utilization and interference free radio operation. An important aspect of spectrum utilization is the underlying time and frequency determination and coordination established by the international time scale which is used by broadcast services throughout the world. This international time scale is Coordinated Universal Time (UTC). UTC is defined by the International Telecommunication Union (ITU-R) and is maintained by the International Bureau of Weights and Measures (BIPM) in cooperation with the International Earth reference and Rotation Service (IERS). The current definition of UTC is a stepped atomic time scale implemented in 1972 to permit UT1 to be recovered from broadcast values of UTC for celestial navigation. Today's telecommunications and navigation systems utilize continuous timing for their data streams, consequently deliberations have been ongoing within the ITU-R on the issue of modifying the definition of UTC to a continuous time scale.