Update on Time and Frequency Activities at PTB

Abstract : The activities in the field of time and frequency metrology pursued at PTB are reviewed. Among the recent milestones have been the development and quasi-continuous operation of a cesium fountain frequency standard, the realization of a free atomic time scale TAF (PTB) based on the fountain results, and the cooperation in international time comparison projects using GPS carrier-phase receivers and TWSTFT in Ku-band and X-band.