Microsemi SyncServer S600 User Manual page 201

NOT include GPS will not be capable of learning about pending
leapseconds or the current UTC offset, so the discussion above is
applicable only to combinations that included the GPS constellation. When
GPS is not included, the manual methods for indicating pending
leapseconds or setting the correct UTC offset are available.
The other inputs (NTP, PTP (not available as an input in release 2.0), and the

IRIG codes shown) have expected notification timeframes (with respect to the
leap moment) as shown. What these mean is that, even if there is knowledge of a
leap pending in advance of these timeframes (such as would certainly occur with
a GPS time reference), the indication on an output of each type should be "held
off" until within that timeframe. As shown, with an NTP output the pending leap
should not be indicated any sooner than 1 day prior to the event. With PTP, the
leap is held off until ½ day prior to the leap event, and finally these special IRIG
codes do not announce the pending leap until the final minute before the leap
event.
You can think about how these timeframes impact each of these signal types
both as an input and as an output, there are some interesting consequences:
– When the leap pending is taken from any of these signals, it will not be
detected at the S6xx (at best) until within the appropriate timeframe.
– The S6xx will always do its best on its outputs to fulfill the complete
timeframe for that output. However, what happens when the input
providing the pending leap has a shorter pre-notification period than an
output that is configured? For example, if the incoming signal that provides
the leap notification is an IRIG 1344 and the S6xx is configured to function
as an NTP Primary Server, the prenotification of the pending leap on NTP
will be (at best) one minute because the IRIG 1344 won't inform the S6xx
earlier than one minute before and therefore this status cannot be
conveyed on any output sooner than that.
098-00720-000 Revision D1 – February, 2018
Chapter 6 Provisioning
Provisioning Inputs with Manual Entry Controls
SyncServer 600 Series User's Guide 201