Orolia Spectracom VelaSync 1232, User Manual

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correct for the Leap Second (unless the System Time’s timescale is configured as
either GPS or TAI).
3.2.3.2 Leap Second Alert Notification
VelaSync will announce a pending Leap Second adjustment by the following methods:
ASCII Data Formats 2 and 7 (among other formats) from the ASCII Data option
modules contain a Leap Second indicator. During the entire calendar month pre-
ceding a Leap Second adjustment, these Formats indicate that at the end of the cur-
rent month a Leap Second Adjustment will be made by using the character ‘L’
rather than a ‘_ ‘ [space] in the data stream. Note that this does not indicate the dir-
ection of the adjustment as adding or removing seconds. These formats always
assume that the Leap Second will 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 condition 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.
VelaSync will make the correction at the right time. However, because com-
puters 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 correction at the right time.
3.2.3.3 Leap Second Correction Sequence
The following is the time sequence pattern in seconds that VelaSync 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
3.2 System Time
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