Effects of the 2019 GPS Rollover on NI Timing & Sync Hardware

Updated Apr 3, 2019

Reported In

Hardware

  • PXI-6683
  • PXI-6682
  • NI-9467

Issue Details

I have heard that there is an upcoming rollover of GPS time that will occur in April of 2019. Why is this rollover occurring? If I am working with an application programmed to use GPS time synchronization via an NI timing & synchronization device (e.g. NI PXI-6682, PXI-6682H, PXI-6683, PXI-6683H, or NI 9467), should I be concerned that the rollover will affect the performance of my hardware or the application?

Solution

GPS synchronization on NI products will not be impacted by the April 6, 2019 rollover. NI R&D has performed tests with our hardware supporting GPS to ensure that the hardware continues to track time properly, and the device's users will not need to take any special action to prepare for the rollover.

The GPS standard defines that time is communicated by transmitting both (a.) the current week, and (b.) the number of seconds elapsed in the current week. Typically, these two values are used to calculate the current time in a more human-readable format (e.g. DD/MM/YYYY HH:MM:SS).
The value used to store the current week is a 10-bit binary number, meaning that it reaches a maximum at 2^10 = 1,024 weeks, after which it rolls back to 0. This rollover has already occurred once, on August 21, 1999. It will happen for the second time on April 6, 2019.

Many GPS receivers on the market are built with firmware that can account for the rollover programmatically. National Instruments Timing & Synchronization hardware is built with GPS receivers that can be programmed by the driver software (NI-Sync, NI-RIO) to interpret time both before and after the rollover.

As of 2019, with the current software provided, these products are guaranteed to function correctly until a certain date, as provided in the table below. Beyond this date, there may be a software, firmware, or other upgrade necessary in order to continue using these products. If you are designing a new system and intend for the system to run beyond these dates, you are recommended to contact NI support to discuss your design considerations further with an NI Engineer.
 

ProductGuaranteed Operation End Date
PXI-6682November 24, 2029
PXI-6683(H)May 11, 2030
NI 9467January 27, 2029