Why Do My GPS Test Panel and The NI Sync Get Time VI Return Different Times?

Updated Apr 2, 2020

Reported In


  • PXI-668XH
  • PXI-6682
  • PXI-6683

Issue Details

I am currently using the GPS Test Panel for the PXI-6682 to retrieve the current time.  However, when I use the NI Sync Get Time VI, the time on the VI and the Test Panel are offset by 19 seconds. 
What is causing this disparity?
What time is the NI Sync Get Time VI retrieving?



The NI-Sync Get Time VI will return International Atomic Time (TAI) while the GPS Test Panel, NI-Sync Read Last GPS and IRIG Timestamp VI's will return Global Positioning System (GPS) time.  
Since GPS time is not adjusted for leap seconds, it is offset by 19 seconds from TAI time.  
The KnowledgeBase UTC, TAI, and GPS Time Scale for NI Synchronization Interfaces gives more information about UTC, TAI, and GPS time scales.