The "Local System" Reference - Safran SecureSync 2400 User Manual

Use case "Local System Time"
The Local System reference when used for
using its current Time-of-Day (ToD) for Time, while synchronized to an external
1PPS reference.
While you may intentionally offset the time in this scenario, the second will be pre-
cisely aligned to the external 1PPS reference. Therefore, this use case qualifies as
a legitimate, traceable time source.
Instead of an offset time, Local System can also be used as a backup Time ref-
erence (e.g., Priority "2"): Should the external Time reference become invalid, the
Local System Time will become the valid backup reference, disciplined by the
external 1PPS reference: SecureSync will transition to the Local System Time,
without going into Holdover.
Use case "Local System 1PPS"
The Local System reference can also be used for 1PPS: This allows SecureSync to
operate using an external ToD for time, while generating 1PPS from its own
internal oscillator.
In this rare use case the 1PPS is NOT aligned to any standard, therefore the time
may drift, and must be considered untraceable.
3.3.1.3 The "User/User" Reference
While it is normally not required, it is possible for you as the "User" to override the
System Time (even if it is synchronized to a valid reference) with a manually set
time, steered by an undisciplined oscillator, and use this manually set Time as an
output reference. This concept is referred to as the User/User reference, because
both the Time, and the 1PPS reference are not linked to any UTC-based external
reference, but hand-set by you.
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Note: For SecureSync to operate as a
must have either a valid external Time reference, or a valid external
1PPS reference.
When the Time reference is configured as
tem Time is considered a valid reference, as long as the external 1PPS input
reference is valid.
Vice versa, when the 1PPS reference is configured as
SecureSync's built-in oscillator is considered a valid reference, as long as
the external Time reference is valid.
3.3 Managing References
Local System reference, you
Local System, SecureSync's Sys-
Local System,
Time allows SecureSync to operate
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