See also below, "How long will the User/User reference be valid?": The notion of
limiting the validity of the User/User reference also serves as a safety feature.
How long will the User/User reference be valid?
Since the User/User reference does not qualify as a legitimate, traceable time, it
becomes invalid once VersaSync is reset, or power-cycles, or after the Holdover
Time expires (whichever occurs first). It then needs to be set manually and sub-
mitted again (Edit System Time > Manual Time Set).
The only workaround for this is "Using Battery Backed Time on Startup" on
page163. This will allow VersaSync to apply the User/User reference after a
power-cycle without manual intervention.
How to setup the User/User Reference
See "Manually Setting the Time" on page161.
Using the "User" Reference with Other References
If the User/User reference is used in conjunction with other, external references
(such as GNSS or IRIG), the System Time should be set as accurately as possible:
Otherwise, the large time correction that needs to be bridged when switching
from a lost reference to a valid reference, or from a valid reference to a higher-pri-
ority reference that has become available again, will cause NTP to exit syn-
chronization. If the difference is under 1second, NTP will remain in sync and will
"slew" (over a period of time) to the new reference time.
3.3.1.4 Reference Priorities: EXAMPLES
Example 1 – GNSS as primary reference, IRIG as backup:
In this use case, the objective is to use:
GNSS as the primary Time, and 1PPS reference
IRIG as the backup Time, and 1PPS reference.
Step-by-step procedure:
1. Move the reference which has “GPS 0” in the Time column and “GPS 0” in
the 1PPS column to the top of the table, with a Priority value of 1. Click the
Enabled checkbox.
3.3 Managing References
CHAPTER 3 • VersaSync User Manual Rev. 12
179
To Next Page
Loading...
