Customer Service Center

Objective/Summary The navigation data field that contains the week number is a 10-bit binary number. This limits the range of the week number to 0 – 1023(1024 total weeks). GPS week zero started January 6, 1980. The week number reached its maximum and rolled over on August 21, 1999. The week number then reset to zero, and started counting up from zero again. The next time the counter will reach week 1023 and rollover to zero is at midnight on April 6, 2019. This article explains how to simulate the GPS week rollover using PosAPP.   Environment/Versions PosAPP All Versions Procedure To test a receiver for the GPS week rollover you will need to create a scenario that starts shortly before the week rollover is due to occur and runs for sufficient time to capture the event. This can easily be done in PosAPP be using the following procedure.  Edit the start time of the scenario to start shortly before the event. Right click on "Start time" in the scenario tree and select "Edit..." Edit the start time to a time shortly before the event that is suitable for your testing Edit the “Duration” time to one suitable for your testing Connect the Device Under Test (DUT) and run the newly created scenario.   As the scenario passes midnight on the 6th April 2019 the GPS week number will decrement to 0 and the GPS Week Number (WN) rollover will increment to 2. This is displayed in the “Date/Time” window and promulgated in the Navigation Data.     Notes Spirent now offers a scenario where users can test the effects of this event to make sure that their receivers are capable of handling such an event. For further information contact support@spirent.com