Safran SecureSync 2400 User Manual page 263

more stable the oscillator is without an external reference, the longer this hold-
over period can be and have it still maintain very accurate outputs. The benefit of
Holdover is that time synchronization and the availability of the time outputs is
not immediately lost when input references are no longer available.
While SecureSync is in Holdover, the only difference is the Holdover and asso-
ciated Minor alarm are asserted. There are no changes to NTP or any of the other
outputs, i.e. while in Holdover mode, NTP inside SecureSync continues to be at
the same Stratum level it was at before going into Holdover mode (such as
Stratum 1 when synced to GPS). Should the Holdover period expire, however, or
the unit is rebooted, the NTP Stratum will go to 16, preventing any clients from
being able to sync with SecureSync until GPS or another reference has been
restored.
How long will the unit remain in Holdover mode?
SecureSync will remain in Holdover mode until either:
Note that Holdover mode does not persist through reboots or power cycles. If a
reboot or power cycle occurs while SecureSync is in Holdover mode, it will
power-up and remain in a
and 1PPS input reference becomes available again. While in this state, NTP will be
Stratum 15 and outputs will not be usable. If the input references are restored
and then lost or declared not valid again, SecureSync will then go back into Hol-
dover mode.
What is "Holdover Timeout"?
Holdover Timeout is the user- configurable allowable time period in which
SecureSync remains in Holdover mode before it declares loss of synchronization.
Holdover Timeout can be adjusted according to application- specific require-
ments and preferences. See below for recommendations on how long (short) the
Holdover Timeout should be.
How to configure Holdover Timeout
To set the Holdover Timeout value:
CHAPTER •
3 SecureSync 2400 User Manual Rev. 5.2
a. Any enabled and valid input reference becomes available again: If one or
more references return and are declared valid before the Holdover period
has expired (even momentarily, i.e. for at least one second), SecureSync
exits the Holdover mode and returns to its fully synchronized state.
b. The Holdover Timeout period expires. In this case, SecureSync will declare
loss of synchronization.
Navigate to MANAGEMENT > OTHER:
icon in the Status
"not synchronized" state until at least one valid Time
panel:
3.4 Holdover Mode
Disciplining, and click the GEAR
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