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8.8 Leap second
8.8.1 Introduction to the leap second
A leap second is a one-second adjustment that keeps Coordinated Universal Time
(UTC) in sync with the earth’s rotation. The organization IERS (www.iers.org) decides
within a half year in advance whether a leap second shall be inserted or not.
A leap second can be inserted into UTC time twice a year: on 31th of December or on
30th of June.
A leap second may be added or removed.
The organization IERS (http://www.iers.org) decides within a half year in advance
whether a leap second shall be inserted or not.
8.8.2 Leap second handling by the DTS4160:
The DTS 4160 can be prepared by the following procedures to implement a leap
second:
•
Manual user input
•
Currently used source
•
Ignore Leap second

A received leap second will be saved, so even when the source is not available in
the leap moment the leap second will be done. A saved leap second can only be
cleared, when the leap second mode is changed to no leap second.
Manual user input:
To ensure that the leap second adjustment process starts at the exact time the leap
second may be configured manually.
In this case the leap second adjustment will be executed at the exact date and time
even if the GPS reception is not sufficient.

This procedure is recommended by Mobatime!
GNSS Receiver:
The GNSS satellite system transmits the information of a Leap Second adjustment at
an arbitrary number of months in advance.
Redundant-Link-Mode:
The Redundant-Link provides leap second indication within a 1 hour before
occurrence.
PTP and the leap second
PTP provides leap second indication before occurrence, ether with the Flag 59 or the
Flag 61 depending on the direction of the leap second.
DCF and the leap second
DCF provides leap second indication before occurrence. DCF does not indicate in
which direction the leap second is. The DTS 4160 will in case of a leap second
announcement from DCF insert a second in the leap moment. This is the only direction
which happened so far.
E1 and the leap second
E1 does not have a leap second indication.