The Physikalisch-Technische Bundesanstalt (PTB) is the national metrology institute of the Federal Republic of Germany, with scientific and technical service tasks. It is a higher federal authority and a public-law institution directly under federal government control, without legal capacity, under the auspices of the Federal Ministry for Economic Affairs and Energy. Tasks Together with NIST in the USA and the NPL in Great Britain, PTB ranks among the leading metrology institutes in the world. As the National Metrology Institute of Germany, PTB is Germany's highest and only authority in terms of correct and reliable measurements. The Units and Time Act Bundesgesetzblatt (Federal Law Gazette), volume 2008, part I, No. 28, p. 1185 ff., 11 July 2008] assigns all tasks which are related with the realization and dissemination of the units to PTB. All legally relevant aspects regarding the units as well as PTB’s responsibilities have been combined in this Act. Previously, all questions regarding the units as well as the role of PTB had been distributed among three laws: the Units Act, the Time Act, and the Verification Act. PTB consists of nine technical-scientific divisions (two of them in Berlin), which are subdivided into approx. 60 departments. These again are subdivided into more than 200 working groups. PTB's tasks are as follows: the determination of fundamental and natural constants; the realization, maintenance and dissemination of the legal units of the SI; and safety technology. This spectrum of tasks is supplemented by services such as the German Calibration Service (, DKD) and by metrology for the area regulated by law, metrology for industry, and metrology for technology transfer. As the basis for its tasks, PTB conducts fundamental research and development in the field of metrology in close cooperation with universities, other research institutions, and industry. PTB employs approximately 1900 staff members. It has a total budget of approx. €183 million at its disposal; in 2012, approx. €15 million was, in addition, canvassed as third-party funds for research projects. The Units and Time Act entrusts PTB also especially with the dissemination of legal time in Germany. To have a time basis for this, PTB operates several atomic clocks (currently two cesium clocks and, since 1999 and 2009, respectively, two cesium fountain clocks). By order of PTB, the synchronization of clocks via radio is performed via the time signal transmitter DCF77 operated by Media Broadcast. Computers which are connected to the Internet can