Spectracom PRISMA VelaSync User Manual page 121

Use cases for the "User/User" reference
The User/User reference is provided for the following use cases:
a.
b.
c.
Combining a User Time reference with a non-User 1PPS reference or vice versa is not a typical
use case. Use the Local System reference instead, see "The "Local System" Reference" on the pre-
vious page.
Built-in safety barrier
In order to "validate" (=
manually submitted every time after VelaSync reboots or resets, or after the Holdover period
has expired: In the Edit System Time window, the checkbox Manual Time Set must be checked.
The System Time displayed in the field below will become valid the moment the Submit button is
clicked.
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3 VelaSync User's Manual Rev. 1
Caution: Since the User/User
does not qualify as a legitimate time source. Operating VelaSync with a manually
set User time bears the risk of inadvertently outputting an illegitimate System Time
thought to be a valid reference time.
No external references are available (yet), but you need a reference for testing or setup
purposes. This may be the case e.g., while waiting for a GNSS antenna to be installed.
No external references are required e.g., if VelaSync is used solely to synchronize com-
puters on a network, with no need for traceable UTC-based timing.
To utilize a backup reference as soon as possible after a power cycle or reboot of
VelaSync, while waiting for the primary reference (e.g., GNSS) to become valid. To this
end, in the Edit System Time window, the checkbox Synchronize to Battery Backed Time on
Startup must be checked, AND the User/User reference is assigned a reference priority
number other than "1". Note that a Time jump and/or 1PPS jump are likely to happen
once the primary reference becomes valid.
status lights) the User/User reference, the hand-set time must be
green
reference is not traceable to a valid reference, it
3.3 Managing References
109