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Frequency standard - Wikipedia, the free encyclopedia (207 words) |
 | A frequency standard is a stable oscillator used for frequency calibration or reference. |
| A frequency standard generates a fundamental frequency with a high degree of accuracy and precision. |
| Frequency standards in a network or facility are sometimes administratively designated as "primary" or "secondary." The terms "primary" and "secondary," as used in this context, should not be confused with the respective technical meanings of these words in the discipline of precise time and frequency. |
| Time and Frequency (762 words) |
| Frequency standards, particularly optical frequency standards, based on stored ions have the potential for higher accuracy than the best current standards, which are based on the neutral cesium atom with a transition in the microwave region, since observation times are much longer and fractional linewidths are much smaller. |
| The first atomic frequency standard, based on ammonia, was built in 1950 at NIST in Washington, D.C. Since then, we have constructed a series of seven standards based on cesium beams with performances improving at a rate of better than an order of magnitude every 10 years. |
| The average of the outputs of these standards is extremely stable and serves as the operational standard for all calibrations and broadcast services. |
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