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Chapter 5 Command Reference
System Time
Operating and Programming Guide 5-79
Reading Leap Second Status ______________________________
This query returns the leap second difference accumulated between GPS time
and UTC time since the beginning of GPS time. The time units are seconds.
Response
An example response is:
+10
which indicates that the accumulated leap second difference between the GPS
time and UTC is 10 seconds.
Context Dependencies
This query is not valid prior to the first lock following powerup (see bit 2 of the
Powerup Status Register) or :SYSTem:PRESet. Sending this query before the
first lock will generate error -230.
Theory
The leap second value is initialized during the power-on sequence by
evaluating :PTIMe:LEAPsecond:ACC = GPS time - UTC time. In July 1994,
the value was 10 seconds.
The value is automatically adjusted immediately following the occurrence of a
leap second correction to the UTC time scale. When a 1 leap second addition is
made to the UTC time scale, the extra second delays the arrival of midnight
UTC causing
:
PTIM:LEAP:ACC? to increase by 1 second. When a 1 leap second
subtraction is made to the UTC time scale, the missing second hastens the
arrival of UTC midnight causing :PTIM:LEAP:ACC? to decrease by 1 second.
:PTIMe:LEAPsecond:ACCumulated?
RESPONSE FORMAT
Returns the leap second difference accumulated between GPS
time and UTC time since the beginning of GPS time. The time
units are seconds.
±
dd