PRC (Precision Reference clock)
A typical PRC provides the reference signal for the timing or synchronization of other clocks within a network or section of a network. In particular, the PRC can also provide the reference signal to the slave clock specified in Recommendation ITU-T G.812 within the network nodes where the PRC is located.
ITU-T G.811 recommendation outlines minimum requirements for timing devices used as primary reference clocks in synchronization networks. These networks include public switched telephone networks (PSTNs) and synchronous digital hierarchy (SDH) networks.
The long-term accuracy of the PRC should be maintained at 1 part in 10^11 or better with verification to coordinated universal time (UTC). A PRC may be realized as an autonomous clock, operating independently of other sources.