Spectracom NetClock 9400 Series, Руководство пользователя

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the reference is selected.
If an output reference is using the GPS or TAI timescale, and the System Time is set to “UTC”,
then the GPS Offset box in the Edit GPS Offset window must be populated with the proper
timescale offset value in order for the time on the output reference to be correct. Some ref
erences (like GNSS) provide the timescale offset to the system. In the event that the input ref
erence being used does not provide this information, it must be set in through the
Offsets panel
of the Time Management page.
Since the GPS and TAI offsets have a fixed relationship, only the GPS offset can be set. If only
the TAI offset is known, subtract 19 from it to get the GPS offset.
Note: If the System Time is set to the UTC timescale, and all output references
either use the UTC or “local” timescale, then it is not necessary to set the GPS and
TAI timescale Offsets.
Caution: It is imperative to configure any input reference’s timescales appro
priately. Otherwise, a System Time error may occur!
Output timescales
Some of the available NetClock outputs (such as the front panel LED display, the IRIG option
module’s outputs, ASCII data module’s outputs, etc.) won’t necessarily output in the same times
cale selected in the System Time’s timescale field. These outputs have internal conversions that
allow the timescale for the outputs 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 front panel LED display can be configured to still show “local” time, if desired.
Other NetClock outputs will be provided in the same timescale that is selected in the System
timescale field. The NTP output for network synchronization and the time stamps included in all
log entries will be in the same timescale as the configured System timescale. For example, if
“GPS” is selected as the System timescale, the log entries and the time distributed to the network
will all be in GPS time (time broadcasted directly from the GNSS constellation). But, the LED dis
play can still be configured to show the current “local” time.
3.2.1.3 Manually Setting the Time
For some applications, it may not be necessary to synchronize NetClock to a UTC-based ref
erence. Or, a GPS reference is not available yet (e.g., because the antenna is not yet installed),
but the system has to be setup and tested.
In such cases, the System Time can be hand-set, and then used as a User [x] -set System Time. For
more information on when to use this functionality, see "The "User/User" Reference" on
page 167.
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NetClock User Reference Guide Rev. 16
3.2 System Time