Plura TCC70XS, Руководство по установке и эксплуатации

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Installation & Operation Manual TCC70XS
Page 58
4.1.2.2 Handling of a Leap Second
UTC is the worldwide real – time reference. Occasionally, UTC will be corrected introducing a
leap second. It is not possible to predict a leap second; the leap second is determined by the
IERS (International Earth Rotation and Reference Systems Service) and will be announced at the
Bulletin C ( services.iers@obspm.fr ). Basically, it could be a positive or negative adjustment of
the UTC time scale, but – up to now – one second has been added always. UTC forms the
time base of all local time zones. If UTC time jumps, the time of a local time zone will jump
same way.
How does a leap second affect the time of the output signals?
1. If the time of the real – time reference jumps, the time of the output signals will jump at
the very moment when TCC70XS updates its time code generator with time & date of
the real – time reference. This update occurs periodically according to set – up, normally
once a day at a user selectable hour (please refer to “Mode of Local Time Zone
Synchronisation“ at chapter “Reference: Real – Time Clock Adjustment “).
2. If the data of the real – time reference announces a leap second, TCC70XS will be able
to execute the time jump simultaneously with the real – time reference if one of the
following conditions applies:
A: Checkbox “After Leap Second of Reference Input“ is checked.
B: The periodic update has been set to “Every second“.
Please refer to chapter “Reference: Real – Time Clock Adjustment “.
In these cases, TCC70XS is able to calculate the leap second in advance. The minute
will then receive an additional 60 th second.
The sequence of the generated real – time signals (time, date [day/month/year]) then
will be for example:
Local time zone
= UTC Local time zone
= UTC + one hour Local time zone
= UTC
– 01:30
23:59:58, 31/12/05
23:59:59, 31/12/05
23:59:60, 31/12/05
00:00:00, 01/01/06
…
00:59:58, 01/01/06
00:59:59, 01/01/06
00:59:60, 01/01/06
01:00:00, 01/01/06
…
22:29:58, 31/12/05
22:29:59, 31/12/05
22:29:60, 31/12/05
22:30:00, 31/12/05
…
Note: The moment of a time jump because of a leap second can be shifted to a user
defined moment, if the operating mode is switched to FREE before the time jump
event (p lease notice section “ The FREE Mode of the Time Code Generator”) .