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Commercial rubidium clocks are less accurate than caesium atomic clocks, which serve as primary frequency standards, so a rubidium clock is usually used as a secondary frequency standard. Commercial rubidium frequency standards operate by disciplining a crystal oscillator to the rubidium hyperfine transition of 6.8 GHz (6 834 682 610.904 Hz).
Atomic clocks based on rubidium standards are therefore regarded as secondary representations of the second. Rubidium standard clocks are prized for their low cost, small size (commercial standards are as small as 1.7 × 10 5 mm 3) [33] and short-term stability. They are used in many commercial, portable and aerospace applications.
A common size for cells inside cordless tool battery packs. This size is also used in radio-controlled scale vehicle battery packs and some Soviet multimeters. 1 ⁄ 2-, 4 ⁄ 5 - and 5 ⁄ 4-sub-C sizes (differing in length) are also available. Soviet 332 type can be replaced with R10 (#4, 927, BF, U8) or 1.5 V elements from 3 V 2xLR10 packs ...
Download as PDF; Printable version; In other projects ... 18 cesium atomic clocks and 4 hydrogen maser clocks ... National Standard Time and Frequency Laboratory;
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The Time and Frequency Standards Laboratory is a part of the National Physical Laboratory in New Delhi which maintains and calibrates the Indian Standard Time. Features of the Time and Frequency Standards Lab include: Four caesium and rubidium atomic clocks
The CSAC, the world's smallest atomic clock, is 4 x 3.5 x 1 cm (1.5 x 1.4 x 0.4 inches) in size, weighs 35 grams, consumes only 115 mW of power, and can keep time to within 100 microseconds per day after several years of operation. A more stable design based on the vibration of rubidium atoms was demonstrated by NIST in 2019. [5]
The first clock known to strike regularly on the hour, a clock with a verge and foliot mechanism, is recorded in Milan in 1336. [96] By 1341, clocks driven by weights were familiar enough to be able to be adapted for grain mills, [97] and by 1344 the clock in London's Old St Paul's Cathedral had been replaced by one with an escapement. [98]