Since it gets its time from the GPS satellites, all of which contain on-board atomic clocks, if your watch stops you'll always have an accurate clock handy.

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Astrium's role, at its UK centre in Portsmouth, was to integrate all the payload components, including hydrogen-maser atomic clocks, the ultra-precise time-pieces on which Galileo's performance depends.

BBC: Galileo: Europe's version of GPS reaches key phase

These satellites are also equipped with very precise atomic clocks.

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But chip makers are having trouble making more precise beams, and the Global Positioning System, which allows people to locate themselves to within a few metres on the surface of the earth, is limited by the performance of its atomic clocks.

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Rabi was interested in the properties of atomic nuclei, not clocks, and he never pursued the idea.

ECONOMIST: Global positioning: Accuracy is addictive | The

Ordinary, not-marching-in-step atomic beams are already used in precision clocks, and to etch some high-performance computer chips.

ECONOMIST: A new way has been devised to make a peculiar form of matter