A

Trimble Standard Interface Protocol

Leap Second Flag

Leap seconds are inserted into the UTC timescale to counter the effect of gradual slowing of the earth’s rotation due to friction. The 8F-AD packet provides extensive UTC leap second information to the user application.

The Leap Scheduled bit is set by the receiver, when the leap second has been scheduled by the GPS control segment. The Control segment may schedule the leap second several weeks before the leap second takes place.

The Leap Pending bit indicates that the leap second will be inserted at the end of the current day.

The GPS Leap Warning bit is set while GPS is operating in the leap exception mode specified in ICD-200.

The Leap in Progress bit is set to 1 at the beginning of the leap second, and cleared at the beginning of the second following the leap event. The date rollover is delayed by one second on the day the leap second is inserted. The date will not increment until the beginning of the first second following the leap second.

Table A-100 Leap Second Flag Definitions

Bit #

Name

Meaning if set to 1

0

UTC Flag

UTC Time is available

 

 

 

1-3

Reserved

N/A

 

 

 

4

Leap Scheduled

GPS Almanac’s leap second date is not in the past.

 

 

 

5

Leap Pending

24-hour warning. Cleared before leap second.

 

 

 

6

GPS Leap Warning

Set +/- 6 hours before/after leap event.

 

 

 

7

Leap in Progress

Leap second is now being inserted.

 

 

 

Acutime 2000 Synchronization Kit User Guide

A-125

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Trimble Outdoors AcutimeTM2000 Synchronization Kit Table A-100 Leap Second Flag Definitions, Bit # Name Meaning if set to