Frequency standard
From Wikipedia, the free encyclopedia
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. Harmonics of this fundamental frequency are used to provide reference points.
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.
[edit] Frequency reference
A frequency reference is an instrument used for providing a stable frequency of some kind. There are different sorts of frequency references, acoustic ones such as tuning forks but also electrical ones that emit a signal of a certain frequency (a frequency standard).
Among the most stable frequency references in the world are caesium-based atomic clocks (caesium standards) and hydrogen masers.
The carrier of time signal transmitters, LORAN-C transmitters and of several longwave and mediumwave broadcastin stations is derived from an atomic clock and can be therefore used as frequency standard.
[edit] References
Federal Standard 1037C and MIL-STD-188
