Network Time Protocol is used to synchronize the Unix hosts with the IRIG time. A VME computer that is integrated with the site time equipment is used as a time server for the site. This time server is locked to the IRIG signal, and so is a stable time source for the site computers.
If the time source is disabled, the internal clocks of the computers will take over and continue to provide the time to the computer. Once the NTP establishes that the site time server is back in operation, it will sync back up to it automatically.