Safran SecureSync 2400 User Manual page 210

3.2 System Time
This will result in SecureSync providing a System Time before one of the external
references becomes available and valid. This will happen automatically, i.e.
without user intervention. As soon an external reference will become available, its
time will take precedence over the battery backed time: The System Clock will
adjust the System Time for any time difference.
Use Cases
Using the Battery Backed Time on Startup is typically used in these cases:
a. If the synchronization state is to be reached as quickly as possible, even if
b. A system is intended to operate autonomously (i.e. without any external ref-
c. A system is used for simulation or testing purposes, and UTC traceability is
The Accuracy of the Battery Backed Time ...
... depends on the accuracy of the hand-set time if the time is set manually in an
autonomous system. In a non-autonomous system (i.e, when using external ref-
erence(s)) SecureSync's System Clock will regularly update the battery-backed
time.
Another factor impacting the accuracy of the battery-backed time is how long a
SecureSync unit is powered off: Any significant amount of time will cause the bat-
tery-backed RTC to drift, i.e. the battery-backed time will become increasingly
inaccurate.
The battery used for the RTC is designed to last for the lifetime of the product.
Distributing battery-backed time over NTP
When distributing a hand-set, battery backed time via NTP, please set the time
relatively close to UTC, so as to prevent NTP synchronization problems when
194
Note: The Battery Backed Time is also referred to as the time main-
tained by the integrated
this means the time distributed initially will most likely be less accurate than
an external time reference.
erences) and
the hand-set time entered manually during commissioning of the sys-
tem is sufficiently accurate
the system needs to be able to completely recover from a temporary
power loss, or similar, without human intervention.
not required.
Real-Time Clock (RTC).
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3 SecureSync 2400 User Manual Rev. 5.2