Don’t blink! On December 31, 2016 at midnight, we will all experience the addition of a leap second! A leap second is a one-second adjustment that is occasionally applied to Coordinated Universal Time (UTC) in order to keep its time of day close to the mean solar time, or UT1.
You can find out more about how leap seconds work here: https://www.timeanddate.com/time/leap-seconds-background.html
Trimble has sent a support note assuring that their GPS receivers should accept the change seamlessly without issue. If you have current GPS/GNSS firmware on your device, it should be able to navigate the leap second seamlessly.
In simple terms, the introduction will occur at the UTC cross over between 31 December 2016 and 1 January 2017. GNSS users must determine the time difference from their location to Greenwich Mean Time (GMT) to determine exactly when they should monitor their GNSS receiver. GLONASS uses UTC in its time system and will introduce a leap second. GLONASS leap second will be introduced at 23:59:60 UTC on 31 December 2016. Any potential issues with tracking of GLONASS will be realized at 00:00:00 UTC on 1 January 2017. To be vigilant with any continuously operating receivers for monitoring, real time networks, etc., we suggest monitoring all receivers during this period. In the event of any tracking issues during the leap second introduction (23:59:60 UTC on 31 December 2016), a simple power cycle of the receiver will fix the problem. Below is a summary of how all Trimble GPS/GNSS receiver firmware will behave with the introduction of the leap second.
Contact CompassTools if you have any trouble with your receiver pertaining to the leap second addition.