PTB’s Time and Frequency Services 2010 – 2014

The recent activities in the field of time and frequency dissemination and applications at PTB were directed towards an improvement in quality and reliability of the offered services. As a foundation of its work, PTB has substantially improved the quality of its local realization of Coordinated Universal Time UTC(PTB). Since February 2010 UTC(PTB) has been derived from an active hydrogen maser steered in frequency by PTB’s primary fountain clocks. During the time between July 2010 and July 2014 the time difference UTC – UTC(PTB) was always less than 9 ns. UTC(PTB) serves as the basis for all of PTB’s time services and international time comparisons. PTB’s time services comprise the operation of NTP time servers, a telephone time service and the standard frequency and time dissemination by the low frequency transmitter DCF77. In order to be able to enhance the security of PTB’s NTP service, PTB is currently working within the Internet Engineering Task Force (IETF) on the standardization of a security protocol that enables secure authentication of NTP time-servers and integrity of the time synchronization packets. Since 2010, PTB’s telephone/modem time service has received a surprisingly increasing number of requests. To accommodate these demands a second device was installed in June 2012 and a third one is held available as a hot backup. Since 2013, about 1800 accesses per day have been processed. The standard frequency and legal time transmitter DCF77 is still the most prominent part of PTB’s time services. The number of operational receivers in Germany and Europe is estimated to be more than 100 million. Thus, a new contract was placed with the operator of the transmitter facilities ensuring guaranteed service until 2021. On the international scene, PTB participated in a number of calibration campaigns to ensure time scale comparisons with uncertainties at the nanosecond level. These comprise two-way satellite time and frequency transfer (TWSTFT) calibration campaigns within Europe, TWSTFT calibration campaigns organized by the U.S. Naval Observatory (USNO), and GNSS calibrations organized by the Bureau International des Poids et Mesures (BIPM). Furthermore, a GPS calibration setup assembled at PTB has been shipped to several metrology laboratories.