G
LOSSARY AND
A
BBREVIATIONS
8029HEPTA-V2/GPS GPS - NTP Time Server with LAN Interface - V08.00
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14.2.1 Time-Specific Expressions
UTC
UTC Time
(
U
niversal
T
ime
C
oordinated) was depending
on the Greenwich Mean Time (GMT) definition of the zero
meridian. While GMT follows astrological calculations,
UTC is based on the stability and accuracy of the Caesium
standard. The leap second was defined in order to cover
this deviation.
Time Zone
The globe was originally divided into 24 longitudinal
segments or time zones. Today, however, there are a
number of time zones which in part apply specifically to
certain individual countries only.
In relation to the time zones, consideration was given to
the fact that local daylight and sunlight coincide at
different times in the individual time zones.
The zero meridian runs through the British city of
Greenwich.
Time Offset
This is the difference between UTC and the valid standard
time of the current time zone.
The Time Offset will be commit from the local time zone.
Local Standard Time
(winter time)
Standard Time = UTC + Time Offset
The time offset is defined by the local time zone and the
local political regulations.
Daylight Saving Time
(summer time)
Offset of Daylight Saving Time = + 1h
Daylight Saving Time was introduced to reduce the energy
requirement in some countries. In this case one hour is
added to the standard time during the summer months.
Local Time
Local Time = Standard Time if exists with summer / winter
time changeover
Leap Second
A leap second is a second which is added to the official
time (UTC) in order to synchronise this with Greenwich
Mean Time when required.
Leap seconds are defined internationally by the
International Earth Rotation and Reference Systems
Service (IERS)
.
