TAI
: International Atomic Time (Temps Atomique International)
The TAI time scale is based on the SI second and is not adjusted for leap
seconds. As of October 2017, TAI is ahead of UTC by 36 seconds. TAI is
always ahead of GPS by 19 seconds.
GPS
: The Global Positioning System time is the timescale maintained by
the GPS satellites.
Global Positioning System time is the time scale maintained by the GPS
satellites. The time signal is provided by atomic clocks in the GPS ground
control stations. The UTC–GPS offset as of October 2017 is 17 seconds.
For more information on Timescales, see "Timescales" below.
4.
If you want to override the system time with a
manually set User Time
, check the
Manual
Time Set
checkbox. For information, see "Manually Setting the Time" on the next page.
5.
Click
Submit
to update the System Time and close the window.
3.2.1.2
Timescales
The System Time can be configured to operate in one of several
timescales
, such as UTC, GPS
and TAI
(Temps Atomique International)
. These timescales are based on international time
standards, and are offset from each other by varying numbers of seconds.
When configuring NetClock, in most cases,
UTC
will be the desired timescale to select.
Note:
UTC timescale is also referred to as “ZULU” time. GPS timescale is the raw
GPS time as transmitted by the GNSS satellites (in 2017 the GPS time is currently
18 seconds ahead of UTC time. UTC timescale observes leap seconds while GPS
timescale does not).
Note:
The
TAI
timescale also does not observe leap seconds. The TAI timescale is
fixed to always be 19 seconds ahead of GPS time. As of January, 2017 TAI time
is 37 seconds ahead of UTC.
NetClock's System timescale is configured via the
MANAGEMENT > OTHER: Time Man
agement
screen, see "System Time" on the previous page.
Input timescales
Some of the inputs may not necessarily provide time to NetClock in the same timescale selected
in the System Time’s timescale field. These inputs have internal conversions that allow the times
cale for the inputs to also be independently defined, so that they don’t have to be provided in
the same timescale. For example, the System timescale can be configured as “UTC”, but the IRIG
input data stream can provide NetClock with “local” time, with no time jumps occurring when
3.2 System Time
CHAPTER
3
•
NetClock User Reference Guide
Rev.
16
149
Summary of Contents for NetClock 9400 Series
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