【實用書籍app】Time and Frequency - High precision time dissem...|最夯免費app-綠色工廠好玩App

Time rules our life more than ever. Everybody uses clocks everytime, everywhere. But did you ever wonder, how and especially how exactly time can be measured? Then this App is right for you. It provides indepth background information about atomic clocks and the so called "Time Dissemination Services".

The App focuses on the base unit “second” which is one of the seven base units, defined by the “International System of Units” (SI). The other base units are: metre, kilogram, ampere, kelvin, mole and candela.

A second is the output of atomic clocks and defined as follows: “The second is the duration of 9.192.631.770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom.”

The Bureau International du Temps et des Mésures at Sèvres, near Paris (France) is the controlling-center of the unit “second”, continuously supplied by about 250 atomic clocks located in 61 time laboratories all over the world.

This App is presenting these time laboratories with their:

■ Acronyms,

■ Addresses,

■ URLs,

■ Geographical Coordinates (Longitude and Latitude) and

■ Technical equipments.

The unit “second” (in other words: “the exact time”) is available to everyone directly from these time laboratories by means of their „Time Dissemination Services”.

The App explains the time dissemination methods such as:

■ Telephone Time Service („Telephone voice announcement“, “Automated Computer Time Service”, “Talking Clock Service“, “Speaking Clock Service” etc.),

■ Web Clock Service

Internet Time Service („Network Time Protocol” (NTP))

■ Wireless Time Services via long- or shortwave radio (Standardfrequency and Time Signal broadcasts).

For a better understanding of these time dissemination methods diagrams, images and even audio files are attached.

Finally the App provides a Glossary with terms like: “ACTS Time Code”, “Daytime Protocol”, “Network Time Protocol”, “Primary Standard”, “Stratum” and others that are commonly used in this fascinating area of science.

This App is based on the German book “Zeit & Frequenz” (“Time & Frequency”) published by Gerd Klawitter of the Verlag für Technik und Handwerk, Baden-Baden, Germany. It is available entirely in English language.