Hardware

Molecular clock could greatly improve smartphone navigation

MIT researchers have developed the first molecular clock on a chip, which uses the constant, measurable rotation of molecules—when exposed to a certain frequency of electromagnetic radiation—to keep time. The chip could ...

Telecom

A navigation system with 10 centimeter accuracy

Researchers of Delft University of Technology, Vrije Universiteit Amsterdam and VSL have developed an alternative positioning system that is more robust and accurate than GPS, especially in urban settings. The working prototype ...

Hardware

Galileo Second Generation satellite aces first hardware tests

The new Galileo satellite model from Thales Alenia Space underwent mechanical and signal performance testing this summer at ESA's ESTEC Test Center. Structural models resisted launch-like noise and vibrations while an electrical ...

Atomic clock

An atomic clock is a type of clock that uses an atomic resonance frequency standard as its timekeeping element. They are the most accurate time and frequency standards known, and are used as primary standards for international time distribution services, and to control the frequency of television broadcasts and GPS satellite signals.

Atomic clocks do not use radioactivity, but rather the precise microwave signal that electrons in atoms emit when they change energy levels. Early atomic clocks were masers with attached equipment. Currently the most accurate atomic clocks are based on absorption spectroscopy of cold atoms in atomic fountains such as the NIST-F1.

National standards agencies maintain an accuracy of 10-9 seconds per day (approximately 1 part in 1014), and a precision set by the radio transmitter pumping the maser. The clocks maintain a continuous and stable time scale, International Atomic Time (TAI). For civil time, another time scale is disseminated, Coordinated Universal Time (UTC). UTC is derived from TAI, but synchronized, by using leap seconds, to UT1, which is based on actual rotations of the earth with respect to the mean sun.

This text uses material from Wikipedia, licensed under CC BY-SA