be added, not removed.
NTP Packets contain two Leap Indicator Bits. In the 24 hours preceding a
Leap Second Adjustment, the Leap Indicator Bits (2 bits) which normally
are 00b for sync are 01b (1) for Add a Leap Second and 10b (2) for Remove
a Leap Second. The bit pattern 11b (3) indicates out of sync and in this con-
dition NTP does NOT indicate Leap Seconds. The Sync state indicates Leap
Seconds by indicating sync can be 00b, 01b, or 10b.
PTP Packets provide leap indication with a 12-hour notification window.
Some IRIG formats provide leap second notification indicators.
Note: It is the responsibility of the client software utilizing either the
Data Formats or NTP time stamps to correct for a Leap Second
occurrence. VersaSync will make the correction at the right time.
However, because computers and other systems may not utilize the
time every second, the Leap Second correction may be delayed until
the next scheduled interval, unless the software properly handles
the advance notice of a pending Leap Second and applies the cor-
rection at the right time.
3.2.3.3 Leap Second Correction Sequence
The following is the time sequence pattern in seconds that VersaSync will output
at UTC midnight on the scheduled day (Note: This is NOT local time midnight; the
local time at which the adjustment is made will depend on which Time Zone you
are located in).
A. Sequence of seconds output when adding a second ("positive Leap
Second"):
56, 57, 58, 59, 60, 0, 1, 2, 3 …
B. Sequence of seconds output when subtracting a second ("negative Leap
Second"):
56, 57, 58, 0, 1, 2, 3, 4 …
3.2.3.4 Configuring a Leap Second
To manually correct the System Time for a leap second:
1. Navigate to MANAGEMENT> OTHER: Time Management. The Time Man-
agement screen will be displayed. In the lower left-hand corner, the Leap
Second Information panel will show if a leap second if pending. This panel
3.2 System Time
CHAPTER 3 • VersaSync User Manual Rev. 12
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