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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).
NPL-CsF2, Yb+ and Sr+ ion clocks, Sr lattice clock, 4 hydrogen masers [5] [6] National Physical Laboratory; ... National Standard Time and Frequency Laboratory;
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. Modern rubidium standard tubes last more than ten years, and can cost as little as US$50.
A standard clock comprises a frequency standard, a device to count off the cycles of the oscillation emitted by the frequency standard, and a means of displaying or outputting the result. Frequency standards in a network or facility are sometimes administratively designated as primary or secondary .
A crystal oscillator depends for its frequency on its physical dimensions, which vary with fabrication and environmental conditions. A rubidium standard is a secondary standard even though it uses atomic transitions, because it takes the form of a gas cell through which an optical signal is passed. The gas cell has inherent inaccuracies because ...
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Four caesium and rubidium atomic clocks An innovative time service via telephone line known as Teleclock service was launched on 28 July 2009. [ 1 ] After successful commissioning this type of service in Nepal and Saudi Arabia, initiation of similar service in SAARC countries are being planned.
Seawater contains an average of 125 μg/L of rubidium compared to the much higher value for potassium of 408 mg/L and the much lower value of 0.3 μg/L for caesium. [33] Rubidium is the 18th most abundant element in seawater. [15]: 371 Because of its large ionic radius, rubidium is one of the "incompatible elements". [34]