G.811 ''Timing characteristics of primary reference clocks'' is a recommendation from the
ITU Telecommunication Standardization Sector (ITU-T). It specifies requirements for primary reference clock devices in
synchronization networks
A synchronization network is a network of coupled dynamical systems. It consists of a network connecting oscillators, where oscillators are nodes that emit a signal with somewhat regular (possibly variable) frequency, and are also capable of r ...
. It discusses timing requirements for connecting national telecommunications networks.
Primary reference clocks need to be highly accurate and are often based on
caesium atomic clock
The caesium standard is a primary frequency standard in which the photon absorption by transitions between the two hyperfine ground states of caesium-133 atoms is used to control the output frequency. The first caesium clock was built by Louis ...
s that meet the standards of G.811.
References
External links
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ITU-T recommendations
ITU-T G Series Recommendations