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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 ).
In a time period from 1959 to 1998, NIST developed a series of seven caesium-133 microwave clocks named NBS-1 to NBS-6 and NIST-7 after the agency changed its name from the National Bureau of Standards to the National Institute of Standards and Technology. [10] The first clock had an accuracy of 10 −11, and the last clock had an accuracy of ...
From 1969 to 2019, this number was 0.012 × the mass ratio between the IPK and a carbon 12 atom. [10] The 2019 revision simplified this by assigning the Avogadro constant the exact value 6.022 140 76 × 10 23 elementary entities per mole, thus, uniquely among the base units, the mole maintained its independence from the caesium standard:
English: "Microchip MAC-SA5X miniaturized rubidium atomic clock produces a stable time and frequency reference that maintains a high degree of synchronization to a reference clock, such as a GNSS-derived signal, despite static g-forces or other factors ... measuring only 2 inch by 2 inch and standing less than an inch"
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]
Download QR code; Print/export ... 18 cesium atomic clocks and 4 hydrogen maser clocks ... Space Optical Clock breadboard (Sr lattice clock) [29]
symmetricom.com at the Wayback Machine (archived 2011-07-10) Symmetricom, Inc. was an American company specialized in high precision timekeeping technology. Symmetricom products supported precise timing standards, including GPS -based timing, IEEE 1588 (PTP), Network Time Protocol (NTP), Synchronous Ethernet and DOCSIS timing.
NIST-F1, source of the official time of the United States. NIST-F1 is a cesium fountain clock, a type of atomic clock, in the National Institute of Standards and Technology (NIST) in Boulder, Colorado, and serves as the United States' primary time and frequency standard. The clock took fewer than four years to test and build, and was developed ...