Post by Brent George on Jun 24, 2015 4:29:56 GMT
Important notice to ALL GPS and GNSS users:
As the World's rotation speed slows down, due to the tidal effects the Moon has on the Earth's rotation, the IERS throw in a 'leap second'. The last time this happened was 2012.
Please note this advisory may affect users of all GPS /GNSS equipment no matter what manufacturer equipment they use so please carefully read the following announcement:
Announcement 1 - All GPS/GNSS Users:
The IERS (International Earth Rotation and Reference Systems Service) published the introduction of a leap second at June 30, 23:59:59. See the bulletin C 49 for further details: Bulletin C 49
A positive leap second will be introduced at the end of June 2015. The sequence of dates of the UTC second markers will be:
2015 June 30, 23h 59m 59s
2015 June 30, 23h 59m 60s
2015 July 1, 0h 0m 0s
The difference between UTC and the International Atomic Time TAI is:
from 2012 July 1, 0h UTC, to 2015 July 1 0h UTC : UTC-TAI = - 35s
from 2015 July 1, 0h UTC, until further notice : UTC-TAI = - 36s
Leap seconds can be introduced in UTC at the end of the months of December or June, depending on the evolution of UT1-TAI. Bulletin C is mailed every six months, either to announce a time step in UTC or to confirm that there will be no time step at the next possible date.
Leap second Consequences for the GPS/GNSS users:
Taking the American GPS satellites as an example the Satellites orbit at approximately 14,000 km/hour or 3.8889 km/second, if your GPS time is out by 1 second the satellites will be approx. 4 km out of position. Therefore with the wrong time information the GPS/GNSS receiver will struggle to calculate a cm level position, and it even may fail to get a position.
Please check with your supplier as to what needs to be done to ensure no on-going issues. (Or just stop and have a coffee or your lunch, and restart things afterwards! 